Querying specific class using String name of class

[JPLaverdure]

Hello,

Is there a proper way to retrieve a class using its name other than going through the _decl_class_registry dictionary of declarative_base ?

I'm using the Joined Table Inheritance and would like to enable users to query specific subtypes.

ie: if I have the following structure:

Base  = declarative_base()

class Sample(Base):

  bla

class Tissue(Sample):

  bla

class DNA(Sample):

  bla

I would like to build a query using 'DNA' as class type...

session.query('DNA').all()

But this doesn't work so the solution I found is the following:

session.query(Base._decl_class_registry['DNA'])

Is this the only way to go or is there a cleaner way to obtain a class based on its String name ?

Thanks !

[Mike Gilligan]

`eval` should work. Something like this:

session.query(eval('DNA')).all()

[JPLaverdure]

Hi Mike,

Thanks for the reply. 

I'm just not sure that using `eval` represents a "cleaner" way than my original code...

The Class query options are specified by the end user through a <select> (html form) so using eval poses a security risk I would like to avoid.

I was hoping slqalchemy would give me a clean way to access mapped objects using a String as Identifier. Like a getter of some kind.

JP