CODEWITHSUNDEEP
c#linqentity-framework
Jeff
Jeff

Reputation: 2313

Passing null parameters into LINQ where clause

I have a table where some items may be null. I can query then easily by using a query like so:

db.SomeTable.Where(s => s.SomeCol == null)

Simple enough, but this does not work (No results. I suspect it is searching for an empty string instead; "") when using a variable that happens to be null, like so:

string variable = null;
db.SomeTable.Where(s => s.SomeCol == variable)

Do I have to do something special to get this to work?

Upvotes: 1

Views: 1831

Answers (1)

Robert Horvick
Robert Horvick

Reputation: 4036

Using LinqPad you can see the difference.

The former creates a query like:

select ...
from SomeTable as t0
where t0.SomeCol IS NULL

whereas the latter is

select ...
from SomeTable as t0
where t0.SomeCol = @p0

Instead you can use object.Equals in your test. E.g.,

string test = null;
var q = from c in SomeTable where object.Equals(c.SomeCol, test) select c;

This will generate the appropriate where clause based on the value of the variable used in the condition.

Upvotes: 7

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