Recently I experienced a lot of problems when creating a complex plugin which played around with thousands of records.
When using good, old T-SQL you would experience the following behavior:
| Id | Name |
| 1 | AAA |
| 2 | BBB |
| 3 | CCC |
SELECT Name FROM Table WHERE Id = 2
Result: AAA
UPDATE Table SET Name = ‘ZZZ’ WHERE Id = 2
SELECT Id FROM Table WHERE Name = ‘ZZZ’
Result: 2
Being naïve and lazy I expected the same behavior from the LINQ 2 CRM data provider – wrong! Remember about caching. This doesn’t happen every time, but from time to time, especially when doing operations one after another querying for a value you just set a moment before, will simply return NULL. This off course caused a lot of strange and hard to find errors.
In CRM it sometimes works like this:
SELECT Name FROM Table WHERE Id = 2
Result: AAA
UPDATE Table SET Name = ‘ZZZ’ WHERE Id = 2
SELECT Id FROM Table WHERE Name = ‘ZZZ’
Result: NULL
Off course when doing a standard FetchXML or QueryExpression everything is OK.
The solution – recreate the Data Context before each query – dataContext = new DataContext(), or as minimum before each query to an entity you used before. This will of course lower the performance a little, but let’s be honest 99,99% of the time is spend inside the query.
To be completely fair I have experienced similar issues with the “Portal Extensions” from CRM 4 but didn’t think Microsoft made CRM 2011 backward compatible in this matter
The SDK makes the impression that the LINQ queries are simply translated into QueryExpressions, apparently they are not.
