I'm trying to build a query system where given a filter parameter name, I
can figure out which DeclarativeBase class it is attached to. I need to do
this for a mix of standard InstrumentedAttributes and Hybrid
Properties/Expressions. I have several Declarative Base classes with
hybrid properties / expressions defined, in addition to the standard
InstrumentedAttributes from the actual table. mydb.dataModelClasses.Cube
for example.
For a standard attribute, I can access the class using the class_ variable.
Standard Attribute on the DeclarativeBase class Cube
type(datadb.Cube.id)
sqlalchemy.orm.attributes.InstrumentedAttribute
print datadb.Cube.id.class_
mydb.DataModelClasses.Cube
What's the best way to retrieve this same information for a hybrid
expression? My expressions are other types, thus don't have the class_
attribute. One example of my hybrid property defined in the Cube class
@hybrid_property
def plateifu(self):
return '{0}-{1}'.format(self.plate, self.ifu.name)
@plateifu.expression
def plateifu(cls):
return func.concat(Cube.plate, '-', IFUDesign.name)
type(datadb.Cube.plateifu)
sqlalchemy.sql.functions.concat
Since this property is now a function concat, what's the best way to
retrieve the name of the class that this property is attached to, namely '
mydb.DataModelClasses.Cube'? It doesn't seem to have a .class_ or .parent
attribute. Is there a way to add a new attribute onto my hybrid columns
that let me access the parent class?
I need to do this for a variety of hybrid properties/expressions, that are
all constructed in unique ways. This particular example is a function
concat, however I have others that are of type
sqlalchemy.sql.elements.BinaryExpression.
Is there a way to generically do this no matter the type of hybrid
expression I define?
Thanks.
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