Cosmos DB read call

Question

I'm making a call to Azure Cosmos DB where I know the data I'm querying does NOT exist.

I was expecting to get a null value but instead I'm getting:

Enumeration yielded no results

How do I test whether I received a value or not? I was testing for null which doesn't work because the outcome is not null.

My code looks something like this:

var result = await _client.ReadQuery<myObject>(AccountsCollection, sql, pa);
if(result == null)
   return null;

Check for .Any() in addition to null: if(result == null || !result.Any()) — maccettura
– maccettura, Commented Oct 4, 2017 at 21:10
Still skipping the line where I check for null or Any(). I think it has something to do with the async call. I guess I'm getting a promise not a result. — Sam
– Sam, Commented Oct 4, 2017 at 21:13
Well 2 things, use var only when the type is obvious (i.e var foo = new DateTime()). Also, make sure your any logic matches what I put in the comment above. If result is null OR result does NOT have any — maccettura
– maccettura, Commented Oct 4, 2017 at 21:15
Also, it looks like you are using HttpClient to read from Cosmos instead of the Cosmos library. Any reason for that? — maccettura
– maccettura, Commented Oct 4, 2017 at 21:16
Sorry, it does work! I didn't use the "not" i.e. ! before Any(). I am using Cosmos DB library. I'm not using HttpClient. I placed my Cosmos DB logic in a different class which I called _client which is only a wrapper around Cosmos DB library. Thank you for your help! — Sam
– Sam, Commented Oct 4, 2017 at 21:19

maccettura · Accepted Answer · 2017-10-04 21:22:01Z

1

Instead of just checking on result == null you should use the LINQ extension method .Any() to see if there are any items that match a condition (in your case the condition is just anything existing in the collection):

if(result == null || !result.Any())
{
    return null;
}

answered Oct 4, 2017 at 21:22

maccettura

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