C# Eval Expression How to use LINQ with Dynamic Expression

Dynamically building a LINQ by adding a Where clause or OrderBy clause coming from user input is a very common scenario.

LINQ is a great addition to .NET, and is one of the most used features for ORM, such as Entity Framework, but it lacks the flexibility to create a dynamic query.

To overcome that limitation, there are 2 FREE common solutions (both from ZZZ Projects):

Most of the time, the C# Eval Expression is the best solution for using LINQ Dynamic:

  • Using LINQ Dynamic method is free (you don't have to purchase a license)
  • Use the C# Language
  • Doesn't "interpret" the expression, unlike other libraries, instead it parses the expression and calls the underlying LINQ method
  • Easy to pass parameters via anonymous type or dictionary
  • Easy to know when a Dynamic method is used (they have all the same suffix!)

Let me repeat one more time one of its advantages: The C# Eval Expression is free when using LINQ Dynamic method.

Otherwise, another great alternative is using Dynamic LINQ which is also free. It makes it very easy to customize your query through a string. One major advantage and disadvantage at the same time is it doesn't use a C# syntax but instead its homemade syntax. If you want to learn more about this library, we recommend reading his documentation

Parameters

Before going deeper into the subject, let's see how parameters can be passed through a LINQ Dynamic method. Like Execute Methods, you can pass parameter through:

  • Using an Anonymous Type
  • Using a Class Instance
  • Using a Dictionary<string, TValue>
  • Using an Expando Object
  • Using parameter values

Method

Let's see first all LINQ methods available:

Category Name Description
Misc. Execute The LINQ Execute method lets you use a dynamic string expression to execute any LINQ methods. That is our most powerful LINQ method.
Deferred DistinctDynamic The LINQ DistinctDynamic method returns distinct elements from a sequence.
Deferred GroupByDynamic The LINQ GroupByDynamic method groups the elements of a sequence. You can use a dynamic string expression to specify columns.
Deferred OrderByDescendingDynamic The LINQ OrderByDescendingDynamic method sorts the elements of a sequence in descending order. You can use a dynamic string expression to specify columns.
Deferred OrderByDynamic The LINQ OrderByDynamic method sorts the elements of a sequence in ascending order. You can use a dynamic string expression to specify columns.
Deferred ReserveDynamic The LINQ ReserveDynamic method inverts the order of the elements in a sequence.
Deferred SelectDynamic The LINQ SelectDynamic projects each element of a sequence into a new form. You can use a dynamic string expression to select a specific column.
Deferred SelectManyDynamic The LINQ SelectManyDynamic projects each element of a sequence to an IEnumerable and flattens the resulting sequences into one sequence. You can use a dynamic string expression to select a specific column.
Deferred SkipWhileDynamic The LINQ SkipWhileDynamic method bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. You can use a dynamic string expression to create the predicate.
Deferred TakeWhileDynamic The LINQ TakeWhileDynamic method returns elements from a sequence as long as a specified condition is true, and then skips the remaining elements. You can use a dynamic string expression to create the predicate.
Deferred ThenByDescendingDynamic The LINQ ThenByDescendingDynamic method performs a subsequent ordering of the element in a sequence in descending order. You can use a dynamic string expression to specify columns in the sorting.
Deferred ThenByDynamic The LINQ ThenByDynamic method performs a subsequent ordering of the element in a sequence in ascending order. You can use a dynamic string expression to specify columns in the sorting.
Deferred WhereDynamic The LINQ WhereDynamic method filters a sequence of values based on a predicate. You can use a dynamic string expression to create the predicate.
Immediate AllDynamic The LINQ AllDynamic method determines whether all elements of a sequence exists. You can use a dynamic string expression to filter elements that satisfy the condition.
Immediate AnyDynamic The LINQ AnyDynamic method determines whether any element of a sequence exists. You can use a dynamic string expression to filter elements that satisfy the condition.
Immediate CountDynamic The LINQ CountDynamic method returns the number of elements in a sequence. You can use a dynamic string expression to count the number of elements that satisfy the condition.
Immediate ElementAtDynamic The LINQ ElementAtDynamic method returns the element at a specified index in a sequence.
Immediate FirstDynamic The LINQ FirstDynamic returns the first element of a sequence. You can use a dynamic string expression to filter elements that satisfy the condition.
Immediate FirstOrDefaultDynamic The LINQ FirstOrDefaultDynamic returns the first element of a sequence, or a default value if no element is found. You can use a dynamic string expression to filter elements that satisfy the condition.
Immediate LastDynamic The LINQ LastDynamic returns the last element of a sequence. You can use a dynamic string expression to filter elements that satisfy the condition.
Immediate LastOrDefaultDynamic The LINQ LastOrDefaultDynamic returns the last element of a sequence, or a default value if no element is found. You can use a dynamic string expression to filter elements that satisfy the condition.
Immediate LongCountDynamic The LINQ LongCountDynamic method returns an Int64 that represents the number of elements in a sequence. You can use a dynamic string expression to count the number of elements that satisfy the condition.
Immediate MaxDynamic The LINQ MaxDynamic returns the maximum value in a sequence. You can use a dynamic string expression to select a specific column.
Immediate MinDynamic The LINQ MinDynamic returns the minimum value in a sequence. You can use a dynamic string expression to select a specific column.
Immediate SelectToListDynamic The LINQ SelectToListDynamic projects each element of a sequence into a new form and create a List from it. You can use a dynamic string expression to select a specific column
Immediate SelectManyToListDynamic The LINQ SelectManyToListDynamic projects each element of a sequence to an IEnumerable, and flattens the resulting sequences into one sequence and creates a List from it. You can use a dynamic string expression to select a specific column.
Immediate SingleDynamic The LINQ SingleDynamic returns a single, specific element of a sequence. You can use a dynamic string expression to filter elements that satisfy the condition.
Immediate SingleOrDefaultDynamic The LINQ SingleDynamic returns a single, specific element of a sequence, or a default value if that element is not found. You can use a dynamic string expression to filter elements that satisfy the condition.
Immediate SumDynamic The LINQ SumDynamic returns the sum of a sequence of numeric values. You can use a dynamic string expression to select a specific column.
Immediate ToArrayDynamic The LINQ ToArrayDynamic creates an Array from an IEnumerable.
Immediate ToListDynamic The LINQ ToListDynamic creates a List from an IEnumerable.

LINQ Execute Method

The LINQ Execute method lets you use a dynamic string expression to execute any LINQ methods.

That is the most powerful LINQ method, as it allows you to chain multiple LINQ expressions one after another one.

Keep in mind that you currently execute C# code, so you should call directly LINQ method (Where) and not LINQ dynamic method (WhereDynamic).

In this example, we will select a list of product and dynamically perform a Where clause by their value, then an Order By and return a List.

var list = new List<int>() { 1, 2, 3, 4, 5 };

var list2 = list.Execute<List<int>>("Where(x => x > 2).OrderBy(x => x).ToList()");
var list3 = list.Execute<List<int>>("Where(x => x > y).OrderBy(x => x).ToList()", new { y = 2 });

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LINQ DistinctDynamic Method

The LINQ DistinctDynamic method returns distinct elements from a sequence.

In this example, we will combine 2 lists of products and perform a distinct to return an unique list of products.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/" };

var list1 = new List<Product>() { product1, product2, product3 };
var list2 = new List<Product>() { product1 };

var combinedList = list1.Concat(list2);
var distinctList = list1.DistinctDynamic();

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LINQ GroupByDynamic Method

The LINQ GroupByDynamic method groups the elements of a sequence. You can use a dynamic string expression to specify columns.

In this example, we will create a list of product and group them by their type using a dynamic expression and select only the first group.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };
var firstGroup = list.GroupByDynamic("x => x.Type").Execute<List<Product>>(".First().ToList()");

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LINQ OrderByDescendingDynamic Method

The LINQ OrderByDescendingDynamic method sorts the elements of a sequence in descending order. You can use a dynamic string expression to specify columns.

In this example, we will create a list of product and order them dynamically by their name in descending order.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };

var list = new List<Product>() { product1, product2, product3 };
var orderByDescendingList = list.OrderByDescendingDynamic("x => x.Name").ToList();

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LINQ OrderByDynamic Method

The LINQ OrderByDynamic method sorts the elements of a sequence in ascending order. You can use a dynamic string expression to specify columns.

In this example, we will create a list of product and order them dynamically by their name in ascending order.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };

var list = new List<Product>() { product1, product2, product3 };
var orderByList = list.OrderByDynamic("x => x.Name").ToList();

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LINQ ReserveDynamic Method

The LINQ ReserveDynamic method inverts the order of the elements in a sequence.

In this example, we will create a list of product and then we will reverse the list order.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };

var list = new List<Product>() { product1, product2, product3 };

list.ReverseDynamic();

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LINQ SelectDynamic Method

The LINQ SelectDynamic projects each element of a sequence into a new form. You can use a dynamic string expression to select a specific column.

In this example, we will dynamically select some product properties, and return an anonymous list.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };

var list = new List<Product>() { product1, product2, product3 };
var anonymousList = list.SelectDynamic("x => new { x.Name, x.Url }").ToList();

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LINQ SelectManyDynamic Method

The LINQ SelectManyDynamic projects each element of a sequence to an IEnumerable and flattens the resulting sequences into one sequence. You can use a dynamic string expression to select a specific column.

In this example, we will dynamically select products from different catalogs, and return the full products list.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/" };

var catalog1 = new Catalog() { Type = "Paid", Products = new List<Product>() { product1, product2, product3 }};
var catalog2 = new Catalog() { Type = "Free", Products = new List<Product>() { product4, product5, product6 }};

var catalogs = new List<Catalog>() { catalog1, catalog2 };

var products = catalogs.SelectManyDynamic("x => x.Products").ToList();

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LINQ SkipWhileDynamic Method

The LINQ SkipWhileDynamic method bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. You can use a dynamic string expression to create the predicate.

In this example, we will create a list of product and ordering them descending per type and skipping all paid products (instead of using a where clause).

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };
var skipWhileList = list.OrderByDescendingDynamic("x => x.Type").SkipWhileDynamic("x => x.Type == 'Paid'").ToList();

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LINQ TakeWhileDynamic Method

The LINQ TakeWhileDynamic method returns elements from a sequence as long as a specified condition is true, and then skips the remaining elements. You can use a dynamic string expression to create the predicate.

In this example, we will create a list of product and ordering them descending per type and taking all paid products (instead of using a where clause).

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };
var takeWhileList = list.OrderByDescendingDynamic("x => x.Type").TakeWhileDynamic("x => x.Type == 'Paid'").ToList();

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LINQ ThenByDescendingDynamic Method

The LINQ ThenByDescendingDynamic method performs a subsequent ordering of the element in a sequence in descending order. You can use a dynamic string expression to specify columns in the sorting.

In this example, we will create a list of product and order them dynamically by type and then by their name in descending order.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };
var thenByDescendingList = list.OrderByDynamic("x => x.Type").ThenByDescendingDynamic("x => x.Name").ToList();

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LINQ ThenByDynamic Method

The LINQ ThenByDynamic method performs a subsequent ordering of the element in a sequence in ascending order. You can use a dynamic string expression to specify columns in the sorting.

In this example, we will create a list of product and order them dynamically by type and then by their name in ascending order.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };
var thenByList = list.OrderByDynamic("x => x.Type").ThenByDynamic("x => x.Name").ToList();

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LINQ WhereDynamic Method

The LINQ WhereDynamic method filters a sequence of values based on a predicate. You can use a dynamic string expression to create the predicate.

In this example, we will create a list of product and filter them by their type.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };

var whereList1 = list.WhereDynamic("x => x.Type == 'Paid'").ToList();
var whereList2 = list.WhereDynamic("x => x.Type == type", new { type = "Paid" }).ToList();

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LINQ AllDynamic Method

The LINQ AllDynamic method determines whether all elements of a sequence exist. You can use a dynamic string expression to filter elements that satisfy the condition.

In this example, we will create a list of products and check if they are all paid products.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };

var allBool1 = list.AllDynamic("x => x.Type == 'Paid'");
var allBool2 = list.AllDynamic("x => x.Type == type", new { type = "Paid" });

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LINQ AnyDynamic Method

The LINQ AnyDynamic method determines whether any element of a sequence exists. You can use a dynamic string expression to filter elements that satisfy the condition.

In this example, we will create a list of product and check if there are any paid products.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };

var anyBool1 = list.AnyDynamic("x => x.Type == 'Paid'");
var anyBool2 = list.AnyDynamic("x => x.Type == type", new { type = "Paid" });

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LINQ CountDynamic Method

The LINQ CountDynamic method returns the number of elements in a sequence. You can use a dynamic string expression to count the number of elements that satisfy the condition.

In this example, we will create a list of product and count the number of paid products.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };

var count1 = list.CountDynamic("x => x.Type == 'Paid'");
var count2 = list.CountDynamic("x => x.Type == type", new { type = "Paid" });

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LINQ ElementAtDynamic Method

The LINQ ElementAtDynamic method returns the element at a specified index in a sequence.

In this example, we will create a list of product and filter them dynamically by their type, and return the second product found (position 1).

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };

var elementAt = list.WhereDynamic("x => x.Type == 'Paid'").ElementAtDynamic(1);

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LINQ FirstDynamic Method

The LINQ FirstDynamic returns the first element of a sequence. You can use a dynamic string expression to filter elements that satisfy the condition.

In this example, we will create a list of product and return the first product by dynamically filtering them with their type.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };

var first1 = list.FirstDynamic("x => x.Type == 'Paid'");
var first2 = list.FirstDynamic("x => x.Type == type", new { type = "Paid" });

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LINQ FirstOrDefaultDynamic Method

The LINQ FirstOrDefaultDynamic returns the first element of a sequence, or a default value if no element is found. You can use a dynamic string expression to filter elements that satisfy the condition.

In this example, we will create a list of product and return the first product or null by dynamically filtering them with their type.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };

var firstOrDefault1 = list.FirstOrDefaultDynamic("x => x.Type == 'Paid'");
var firstOrDefault2 = list.FirstOrDefaultDynamic("x => x.Type == type", new { type = "Paid" });

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LINQ LastDynamic Method

The LINQ LastDynamic returns the last element of a sequence. You can use a dynamic string expression to filter elements that satisfy the condition.

In this example, we will create a list of product and return the last product by dynamically filtering them with their type.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };

var last1 = list.LastDynamic("x => x.Type == 'Paid'");
var last2 = list.LastDynamic("x => x.Type == type", new { type = "Paid" });

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LINQ LastOrDefaultDynamic Method

The LINQ LastOrDefaultDynamic returns the last element of a sequence, or a default value if no element is found. You can use a dynamic string expression to filter elements that satisfy the condition.

In this example, we will create a list of product and return the last product or null by dynamically filtering them with their type.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };

var lastOrDefault1 = list.LastOrDefaultDynamic("x => x.Type == 'Paid'");
var lastOrDefault2 = list.LastOrDefaultDynamic("x => x.Type == type", new { type = "Paid" });

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LINQ LongCountDynamic Method

The LINQ LongCountDynamic method returns an Int64 that represents the number of elements in a sequence. You can use a dynamic string expression to count the number of elements that satisfy the condition.

In this example, we will create a list of product and count the number of paid products.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };

var longCount1 = list.LongCountDynamic("x => x.Type == 'Paid'");
var longCount2 = list.LongCountDynamic("x => x.Type == type", new { type = "Paid" });

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LINQ MaxDynamic Method

The LINQ MaxDynamic returns the maximum value in a sequence. You can use a dynamic string expression to select a specific column.

In this example, we will create a list of product and get the product name considered as the maximum.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };

var list = new List<Product>() { product1, product2, product3 };

var max = list.MaxDynamic<Product, string>("x => x.Name");

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LINQ MinDynamic Method

The LINQ MinDynamic returns the minimum value in a sequence. You can use a dynamic string expression to select a specific column.

In this example, we will create a list of product and get the product name considered as the minimum.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };

var list = new List<Product>() { product1, product2, product3 };

var min = list.MinDynamic<Product, string>("x => x.Name");

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LINQ SelectToListDynamic Method

The LINQ SelectToListDynamic projects each element of a sequence into a new form and create a List from it. You can use a dynamic string expression to select a specific column.

In this example, we will dynamically select some product properties, cast our list as queryable (a queryable is required for this method), and returns an anonymous list.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };

var list = new List<Product>() { product1, product2, product3 };
var anonymousList = list.AsQueryable().SelectToListDynamic("x => new { x.Name, x.Url }");

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LINQ SelectManyToListDynamic Method

The LINQ SelectManyToListDynamic projects each element of a sequence to an IEnumerable, and flattens the resulting sequences into one sequence and creates a List from it. You can use a dynamic string expression to select a specific column.

In this example, we will dynamically select products from different catalog, cast our list as queryable (a queryable is required for this method), and returns the full products list.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/" };

var catalog1 = new Catalog() { Type = "Paid", Products = new List<Product>() { product1, product2, product3 }};
var catalog2 = new Catalog() { Type = "Free", Products = new List<Product>() { product4, product5, product6 }};

var catalogs = new List<Catalog>() { catalog1, catalog2 };

var products = catalogs.AsQueryable().SelectManyToListDynamic("x => x.Products").ToList();

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LINQ SingleDynamic Method

The LINQ SingleDynamic returns a single, specific element of a sequence. You can use a dynamic string expression to filter elements that satisfy the condition.

In this example, we will create a list of product and return the last product by dynamically filtering them with a name.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };

var single1 = list.SingleDynamic("x => x.Name == 'C# Eval Expression'");
var single2 = list.SingleDynamic("x => x.Name == name", new { name = "C# Eval Expression" });

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LINQ SingleOrDefaultDynamic Method

The LINQ SingleDynamic returns a single, specific element of a sequence, or a default value if that element is not found. You can use a dynamic string expression to filter elements that satisfy the condition.

In this example, we will create a list of product and return the last product by dynamically filtering them with a name.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };

var singleOrDefault1 = list.SingleOrDefaultDynamic("x => x.Name == 'C# Eval Expression'");
var singleOrDefault2 = list.SingleOrDefaultDynamic("x => x.Name == name", new { name = "C# Eval Expression" });

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LINQ SumDynamic Method

The LINQ SumDynamic returns the sum of a sequence of numeric values. You can use a dynamic string expression to select a specific column.

In this example, we will create a list of product and sum the length of all product name characters.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };

var list = new List<Product>() { product1, product2, product3 };

var sum = list.SumDynamic<Product, int>("x => x.Name.Length");

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LINQ ToArrayDynamic Method

The LINQ ToArrayDynamic creates an Array from an IEnumerable.

In this example, we will create a list of product, filter them dynamically by their type, and return the result as an array.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };

var toArray = list.WhereDynamic("x => x.Type == 'Paid'").ToArrayDynamic();

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LINQ ToListDynamic Method

The LINQ ToListDynamic creates a List from an IEnumerable.

In this example, we will create a list of product, filter them dynamically by their type, and return the result as a list.

var product1 = new Product() { Name = "C# Eval Expression", Url = "https://eval-expression.net/", Type = "Paid" };
var product2 = new Product() { Name = "Dapper Plus", Url = "https://dapper-plus.net/", Type = "Paid" };
var product3 = new Product() { Name = "Entity Framework Extensions", Url = "https://entityframework-extensions.net/", Type = "Paid" };
var product4 = new Product() { Name = ".NET Fiddle", Url = "https://dotnetfiddle.net/", Type = "Free" };
var product5 = new Product() { Name = "SQL Fiddle", Url = "https://sqlfiddle.com/", Type = "Free" };
var product6 = new Product() { Name = "ZZZ Code AI", Url = "https://zzzcode.ai/", Type = "Free" };

var list = new List<Product>() { product1, product2, product3, product4, product5, product6 };

var toList = list.WhereDynamic("x => x.Type == 'Paid'").ToListDynamic();

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Last updated: 2025-07-04
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