An expression in Linq that always returns true

In a LINQ expression tree, how do you evaluate a solitary boolean expression?

The following cases are pretty straight forward:...h => h.Enabled == enabled h => h.Enabled == true ...These are ...BinaryExpression... nodes, and you can directly translate them into:...WHERE (Enabled = @p0) WHERE (Enabled = 1) ...The special case(s) that you need to handle are:...h => h.Enabled h => !h.Enabled ...Those are represented differently...

Unable to cast object of type 'System.Linq.Expressions.UnaryExpression' to type 'System.Linq.Expressions.MemberExpression'

This is ...apparently... related to boxing/unboxing. Lambda expressions returning value types that require boxing will be represented as UnaryExpressions whereas those that return reference types will be represented as MemberExpressions.

Expression<Func<T, bool>> with It.IsAny always return true

I'm trying to create a generic testclass to test my generic controllers. Everything is working fine except this: I have a method like this: ...private T GetSingle(Expression<Func<T, bool>> expression) ...I'm trying to setup the test like so:...var Guids = new[] { Guid.NewGuid(), Guid.NewGuid() }; var items = Guids.Select(x => new T {Id = x}); var m...

How to convert between Linq expressions with different return types?

My case was converting interface input type to the concrete type for my MongoDB generic repository....I was converting from...Expression<Func<TIModel, bool>> iFilter ...to...Expression<Func<TModel, bool>> filter ...I just inspired from Ani's answer and converted like:...var filter = Expression.Lambda<Func<TModel, bool>>(iFilter.Body, iFilter.Parame...

How can I create a LINQ-friendly 'return false' expression using C# expression trees?

Can you wrap the entire thing in an if-else expression?...Meaning:...if input return <your normal code> else return false ...The return is implicit in expressions; the return value of the expression will simply be the last value. So you could try:... Expression.Condition ( Expression.NotEqual(input, Expression.Constant("")), ...

Dynamic Linq Expression with return value

If you have simple condition statement like this:...if (condition) return expression1; else return expression2; ...You can transform that into ternary expression: ...condition ? expression1 : expression2.... And then you can create an expression without using ...Label..., ...Return..., or ...Goto.......Expression condition; Expression expre...

How to add an AND/OR expression to the following dynamic linq expression

I think you're making this harder than you have to. In the first part of your code (the ...OrderBy()...), you don't actually need to generate the whole query expression, just the lambda inside it. And in the second part (the optional ...Where()...) you can do pretty much the same thing, just add ...Expression.Equal()... and ...Expression.Constant()...

How to manually build Expression which will return always true?

There is a nice tool which can help you construct expression trees ...http://tryroslyn.azurewebsites.net/... ....I've added a linq to @Ivan`s example of ...GetTrueExpression

Cannot convert from 'System.Linq.Expressions.LambdaExpression' to 'System.Linq.Expressions.Expression

I'm trying to implement expression tree with linq.I am getting error state as cannot convert lambdaexpression to expression. Please help i checked other solution but couldn't help as much ! Below is my code...ParameterExpression pe = Expression.Parameter(typeof(Person), "p"); var expr = Expression.Lambda(Expression.Property(pe, sortByProp), pe); ...

How do I create a lambda expression using return value from another lambda expression?

Neither the question nor the answer is the same as the question "Convert Linq expression “obj => obj.Prop” into “parent => parent.obj.Prop”".... The only duplicate I've found on here lately is the number of duplicate mods with control issues....I'm attempting to make a extension method for Entity Framework that will add a "Contains" call o...