EF custom select with entity property as parameters - entity-framework

Question

For every table (and I have a lot of them) I provide Lookup REST API method in my ASP.Net Core application.
This is part of my query for every table:
context.Users.Select(t => new ViewLookupModel()
{
id = t.Id,
title = t.DisplayName
})
//......
context.Groups.Select(t => new ViewLookupModel()
{
id = t.Id,
title = t.Name
})
But I want to write extension to shrink code I need to write for every table. Something like this:
public static IQueryable<ViewLookupModel> SelectLookup<T>(this IQueryable<T> query, Func<int> idField, Func<string> titleField)
{
return query.Select(t => new ViewLookupModel()
{
id = idField(),
title = titleField()
});
}
And use case:
context.Users.SelectLookup(t => t.Id, t => t.DisplayName)
//......
context.Groups.SelectLookup(t => t.Id, t => t.Title)
But I get error:
Delegate 'Func' does not take 1 arguments.
This and this question seems similar, but I can not get it to work.
I am also interesting in any performance issues when querying database with custom SELECT extension method.

Answer 1

Change your extension method to this and try. Extension method takes T as input and returns the corresponding int or string etc.
public static IQueryable<ViewLookupModel> SelectLookup<T>(this IQueryable<T> query, Func<T,int> idField, Func<T,string> titleField)
{
return query.Select(t => new ViewLookupModel()
{
id = idField(t),
title = titleField(t)
});
}