Question

I have extension method:

public static IQueryable<TResult> WithFieldLike<TResult>(    this IQueryable<TResult> query,    Func<TResult, string> field,    string value) {    Expression<Func<TResult, bool>> expr =         trans => field(trans).Contains(value);    return query.Where(expr); } 

I need change parameter field to type: Expression>. Will be something like.

public static IQueryable<TResult> WithFieldLike<TResult>(    this IQueryable<TResult> query,    Expression<Func<TResult, string>> field,    string value) {    Expression<Func<TResult, bool>> expr = ???    return query.Where(expr); } 

The call of this method is:

var query7 = query.WithFieldLike(trans => trans.DeviceModelNumber, 'ber_3'); 

How should I build the ‘expr’ in this case? Please help.

Answer 1

Deconstruct field and create a new expression, something like this:

var expr = Expression.Lambda<Func<TResult, bool>> (     Expression.Call (field.Body, typeof (string).GetMethod ('Contains'),         Expression.Constant (value)), field.Parameters) ; 

(edited as per Maxs’s refinement in comments)