CODEWITHSUNDEEP
c#.netdynamic-expresso
George Papadakis
George Papadakis

Reputation: 1368

Parse as expression an array containing specific identifier

I am building dynamic lamda expressions from string expressions using ParseAsExpression. The problem is that i cannot figure out how to parse an expression of an array contains an object like mylist.Contains(x.Id)

Full example

 var list = new int[] { 4,5,6};
 var whereFunction = new Interpreter().SetVariable("mylist", list);    
 whereFunction.ParseAsExpression<Func<Person, bool>>("(person.Age == 5 && person.Name.StartsWith(\"G\")) || person.Age == 3 && mylist.Contains(person.Id)", "person");

Upvotes: 0

Views: 529

Answers (2)

Davide Icardi
Davide Icardi

Reputation: 12209

I can confirm this is a bug: https://github.com/davideicardi/DynamicExpresso/issues/68

For now Array.Contains doesn't work.

UPDATE:

Fixed in version 2.0.2.

Upvotes: 1

Dabbas
Dabbas

Reputation: 3230

For now you can do a workaround by implementing an alias extension method for each method doesn't work, like for Contains=>Exists: 

 var list = new int[] { 4,5,6};

 var whereFunction = new Interpreter()
.SetVariable("mylist", list)
.Reference(typeof(ExtensionMethods));

 whereFunction.ParseAsExpression<Func<Person, bool>>("(person.Age == 5 && person.Name.StartsWith(\"G\")) || person.Age == 3 && mylist.Exists(person.Id)", "person");

// Define this class somewhere
public static class ExtensionMethods
{
    public static bool Exists<T>(this IEnumerable arr, T searchKey)
    {
        return ((IEnumerable<T>)arr).Contains(searchKey);
    }
}

I see this is as a stupid workaround, but it'll work.

Upvotes: 2

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