[Qgis-developer] Question about expression compiling

Matthias Kuhn matthias at opengis.ch
Tue Feb 2 15:08:13 PST 2016


Hi David,

Have you had a look at the class QgsSqlExpressionCompiler? Other SQL
dialects inherit from this class and fine tune it. Most work should
already be done in there so you just have to take care of the failing tests.

https://github.com/qgis/QGIS/blob/master/src/core/qgssqlexpressioncompiler.cpp

Matthias

On 02/03/2016 12:01 AM, David Adler wrote:
> We are working on the DB2 expression compiler and testing it with a
> Python driver.
>
> For an expression like NAME IS NULL
> What should be the node type of NULL?  It appears to be
> QgsExpression::ntLiteral but it doesn't seem to have a valid value and
> fails the call to quotedValue().
>
> For now we are using a hack to check if n->dump() == NULL and treating
> it as a special case.
>
> Also, I assume that ILIKE is a case insensitive LIKE.
>
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-- 
Matthias Kuhn
OPENGIS.ch - https://www.opengis.ch
Spatial • (Q)GIS • PostGIS • Open Source


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