SpoiledTechie.com SpoiledTechie.com - 1 month ago 6
C# Question

How do I use LINQ Contains(string[]) instead of Contains(string)

I got one big question.

I got a linq query to put it simply looks like this:

from xx in table
where xx.uid.ToString().Contains(string[])
select xx


The values of the
string[]
array would be numbers like (1,45,20,10,etc...)

the Default for
.Contains
is
.Contains(string)
.

I need it to do this instead:
.Contains(string[])
...

EDIT : One user suggested writing an extension class for
string[]
. I would like to learn how, but any one willing to point me in the right direction?

EDIT : The uid would also be a number. That's why it is converted to a string.

Help anyone?

Answer

spoulson has it nearly right, but you need to create a List<string> from string[] first. Actually a List<int> would be better if uid is also int. List<T> supports Contains(). Doing uid.ToString().Contains(string[]) would imply that the uid as a string contains all of the values of the array as a substring??? Even if you did write the extension method the sense of it would be wrong.

[EDIT]

Unless you changed it around and wrote it for string[] as Mitch Wheat demonstrates, then you'd just be able to skip the conversion step.

[ENDEDIT]

Here is what you want, if you don't do the extension method (unless you already have the collection of potential uids as ints -- then just use List<int>() instead). This uses the chained method syntax, which I think is cleaner, and does the conversion to int to ensure that the query can be used with more providers.

var uids = arrayofuids.Select(id => int.Parse(id)).ToList();

var selected = table.Where(t => uids.Contains(t.uid));
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