Find the Any method on an array of strings

c# expression-trees linq

Question

Given

string[] stringArray = { "test1", "test2", "test3" };

If this returns true, then:

bool doesContain = stringArray.Any(s => "testa test2 testc".Contains(s));

My final objective is to turn this into a linq expression tree. How can I find out the technique information for"Any" ? The next is ineffective since it returns nil.

MethodInfo info = typeof(string[]).GetMethod("Any", BindingFlags.Static | BindingFlags.Public);

Additional clarification

I'm developing search capabilities. I use EF, and so far, creating a dynamic lambda expression tree by utilizing linq expression trees has worked. In this instance, I have a string array from which I can choose any text to appear in a description field. The operational lambda expression used in theWhere is a clause:

c => stringArray.Any(s => c.Description.Contains(s));

I thus require a call to in order to create the lambda expression's body."Any" .

Last code:

As a result of I4V's response, constructing this portion of the expression tree now appears as follows (and functions):

//stringArray.Any(s => c.Description.Contains(s));
if (!String.IsNullOrEmpty(example.Description))
{
    string[] stringArray = example.Description.Split(' '); //split on spaces
    ParameterExpression stringExpression = Expression.Parameter(typeof(string), "s");
    Expression[] argumentArray = new Expression[] { stringExpression };

    Expression containsExpression = Expression.Call(
        Expression.Property(parameterExpression, "Description"),
        typeof(string).GetMethod("Contains"),
        argumentArray);

    Expression lambda = Expression.Lambda(containsExpression, stringExpression);

    Expression descriptionExpression = Expression.Call(
        null,
        typeof(Enumerable)
            .GetMethods()
            .Where(m => m.Name == "Any")
            .First(m => m.GetParameters().Count() == 2)
            .MakeGenericMethod(typeof(string)),
        Expression.Constant(stringArray),
        lambda);}

after thatdescriptionExpression enters a bigger lambda expression tree.

1
4
5/7/2013 6:02:01 PM

Fastest Entity Framework Extensions

Bulk Insert
Bulk Delete
Bulk Update
Bulk Merge

Accepted Answer

maybe along these lines?

var mi = typeof(Enumerable)
            .GetMethods()
            .Where(m => m.Name == "Any")
            .First(m => m.GetParameters().Count() == 2)
            .MakeGenericMethod(typeof(string));

You may also refer to it as:

var result = mi.Invoke(null, new object[] { new string[] { "a", "b" }, 
                                           (Func<string, bool>)(x => x == "a") });
1
5/7/2013 4:01:55 PM

Popular Answer

You may also

// You cannot assign method group to an implicitly-typed local variable,
// but since you know you want to operate on strings, you can fill that in here:
Func<IEnumerable<string>, Func<string,bool>, bool> mi = Enumerable.Any;

mi.Invoke(new string[] { "a", "b" }, (Func<string,bool>)(x=>x=="a"))

Additionally, the IQueryable overload may be useful if you're using Linq to Entities:

Func<IQueryable<string>, Expression<Func<string,bool>>, bool> mi = Queryable.Any;

mi.Invoke(new string[] { "a", "b" }.AsQueryable(), (Expression<Func<string,bool>>)(x=>x=="b"));
Ben Reich

Related Questions

.NET 4.0 Expression Trees: Expression The method "get Item" in type ListT> cannot be found.

I'm having trouble with the issue listed below and am wondering if anybody can provide assistance. I've added comments to the code to make it self-explanatory, but if you still need clarification or additional information, please let me know....Many thanks in advance!...I've been requested to provide a text summary of the issue, so here it is: unde...
.net-4.0 c# expression-trees lambda
asked by d..

String.IndexOf method expression tree

I think there are two issues....The first is how you're receiving the method; rather than getting one with two arguments, you're ...asking... for one with only one string parameter:...var methodCall = typeof (string).GetMethod("IndexOf", new[] { typeof (string), typeof(StringComparison) }); ...The second is the value you...
c# expression-trees linq-expressions reflection
asked by Jon Skeet

ERROR A static method needs a null instance, while a non-static method does not.

An expression tree is what I'm attempting to make. I must read data from a table of data and examine its columns. Only at run time is it known which columns need to be verified, as well as how many. Each column has a List of strings to be verified, and the column names are provided to me as a string array. I experimented with many expression trees,...
c#-4.0 expression-trees lambda linq static-methods
asked by Jani5e

Create array of all ExpressionTree/Func-parameters

The following program's output is:...System.String is first. Second: System.String....The anticipated outcome is: First, hello1. Next, hello2....If I set the Expression's index hardcoded to 1 or 2. It works using Assign(resultArrayAccessor, parameters[0]), but I need the index to come after the variable i.... public static void Main() { ...
c# expression expression-trees lambda
asked by Lars Stenberg

Expression builder function for String.Contains and string[]

in place of...Expression.Equal... You must use...Expression.Call... and provide an instance of Contains MethodInfo. comparable to this...IEnumerable<Expression> expressions = item.Value.Select(value => (Expression)Expression.Call(item.Key.Body, typeof(String).GetMethod("Contains"), Expression.Constant(value, typeof(TValue))));
.net c# expression-trees
asked by Vladimir Sachek

Expressions static method requires null instance non-static method requires non-null instance

Due to my inexperience with Expressions, I keep receiving the following error:...System.ArgumentException : Static method requires null instance, non-static method requires non-null instance.... Parameter name: method...The code looks like this:... int inP = 100; object inParam = inP; Type inParamType = inParam.GetType();...
c# expression-trees
asked by jpa7

How to Convert Predicate to String and String To Predicate

I'm working on a unique project that requires me to convert predicates (or expressions) to strings, save them in a database, get them, convert them back to strings, and then evaluate them because I want to be able to update them at runtime. To implement the ConvertStringToPredicate and ConvertStringToPredicate methods, do assist me....public class ...
c# c#-4.0 expression-trees lambda linq
asked by ArMaN

Expression.PropertyOrField returns "not a member of type 'System.String'" for string property

The process of dynamically creating expressions for a rules engine was going quite well until I attempted to enable the specification of nested types and attributes as operands. Sample:...ExpressionBuilder...public Expression BuildExpression<T>(string propertyName, Enums.Operator ruleOperator, object value, ParameterExpression parameterExpression) ...
.net c# expression-trees lambda
asked by shanomacadaemia

Using Expressions to build Array.Contains for Entity Framework

Finding them is perhaps the most challenging aspect....MethodInfo... of the....Contains()... method. You could utilize...typeof(IEnumerable<string>).GetMethod(...).Where(...)... , however for generic methods with several overloads, it is often difficult to accomplish it correctly. This little hack uses a temporary expression to let the C# compiler ...
c# expression-trees
asked by Ňuf

EF Core SQL Function LIKE Method with Linq Expression not working for Non String types

I can make an invoke expression using SQL functions, as shown below....var likeMethod = typeof(DbFunctionsExtensions).GetMethod("Like", new[] { typeof(DbFunctions), typeof(string), typeof(string) }); Expression.Call(null, likeMethod, Expression.Constant(EF.Functions), searchKeyExpression, Expression.Constant($"%{filter.Value}%")); ...The only thin...
c# ef-core-2.1 entity-framework-core expression-trees
asked by Akshay Joy

Fastest Entity Framework Extensions

Bulk Insert
Bulk Delete
Bulk Update
Bulk Merge
View more on Stack Overflow

Prime Library

Performance

Expression Evaluator

More Projects...
Licensed under: CC-BY-SA with attribution
Not affiliated with Stack Overflow
Licensed under: CC-BY-SA with attribution
Not affiliated with Stack Overflow