how can i get ToLower to work in an expression?

Question

I have the following line of code:

protected Expression<Predicate<DuplicateCheck>> Name= x => x.Name == "smith";

when I add a .ToLower()

protected Expression<Predicate<DuplicateCheck>> Name= x => x.Name.ToLower() == "smith";

to try to generalize the query I get the error

System.Reflection.TargetException: 'Non-static method requires a target.'

Is this not available to use in this way?

How are you using `Name`? What is `Predicate<>`? Reflection is not involved in the definition of `Name` so the library or system you are using it with must be trying to parse the `ExpressionLambda` and doesn't handle complicated expressions. What library are you using? — NetMage, Feb 07 '20 at 20:36

Nguyễn Văn Phong · Answer 1 · 2020-02-07T14:09:30.300

0

System.Reflection.TargetException: 'Non-static method requires a target.'

Normally it happens when the target is null, So you need to check it first like below.

x => x != null && x.Name != null && x.Name.ToLower() == "smith"

edited Feb 07 '20 at 14:09

answered Feb 07 '20 at 13:39

1

this didn't work for me unfortunately... same error. – dstewart101 Feb 07 '20 at 13:45
Did you add more condition `x != null` as I edited my question? – Nguyễn Văn Phong Feb 07 '20 at 14:10
we could simplify it to `x => x?.Name?.ToLower() == "smith"` – Matt.G Feb 07 '20 at 14:31
Yes, If the OP is using `C# 6 features – Null-conditional` – Nguyễn Văn Phong Feb 07 '20 at 14:33

1 Answers1