Can I test a single object against a LINQ function?

Question

I have a LINQ function similar to the one below:

public static Func<Contact, bool> activeContactsFilter = c =>
    !c.suspended &&
    !c.expired &&
    (c.status_id == 1 || c.status_id == 7);

This works great when I need to find out which Contacts amongst an IEnumerable of contacts are "active":

var activeContacts = allContacts.Where(activeContactsFilter);

But what if I want to just check if ONE specific contact is "active"? How do I use this same function for a test on a single object?

Have you tried just calling it `activeContactsFilter(contact1)`? — BartoszKP, Aug 21 '14 at 09:16
@jon [... OK you win.](http://stackoverflow.com/questions/155609/what-is-the-difference-between-a-method-and-a-function) — Rawling, Aug 21 '14 at 09:22
@Jon Emmmm, I'm pretty sure they are *functions* actually (unless I have a very messed up definition for what a function and a method is, which is entirely possible of course) — Dimitar Dimitrov, Aug 21 '14 at 09:41
@Jon oh, that wen't way over my head :P Really hard to detect sarcasm on the net, sorry :) — Dimitar Dimitrov, Aug 21 '14 at 10:12

score 6 · Accepted Answer · edited May 23 '17 at 10:33

6

It's really simple - just call the Func like it was, well, a function:

bool contactIsActive = activeContactsFilter(contactToCheck);

Funcs aren't specifically LINQ-related, they're just useful for LINQ. You can store a method in a Func of the correct type, and (as above) you can call a Func like a method.

Take a look here for more information on Funcs.

edited May 23 '17 at 10:33

Community

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answered Aug 21 '14 at 09:16

Rawling

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Thanks for the quick and detailed answer (also @BartoszKP) - will accept as soon as I'm allowed to by SO. – Jimbo Aug 21 '14 at 09:18

Can I test a single object against a LINQ function?

1 Answers1