Why is a wrapper type generated for single column queries of nullable fields?

[humblehacker]

If I write a single column query for a non-nullable field, say TEXT NOT NULL, then the generated method returns String. But if the field is nullable, the generated method includes a wrapper type that contains the nullable value. I'm sure there's a good reason for this, but what is it?

[bubenheimer]

Related: #2430

[dellisd]

Having a nullable result from a query doesn't really fit with SQLDelight's APIs.

For example consider this query which selects a nullable TEXT column:

getContent:
SELECT content FROM table;

and then you might call the generated query function like this:

tableQueries.getContent().executeAsOneOrNull() // returns a String?

The problem is: If this returns null, did the query return zero rows? Or was the value of content in the table just equal to null?

[humblehacker]

That makes sense. Thanks for the clarification!