[sqlalchemy] Re: Softcoding .filter(...)

[Matt Bodman]

I think he means that if you only need an exact match on your query (instead 
of a 'like' or a '' etc) you can do this:

dict_from_web = {'Title':'The Book','Author':'Bob Smith'}

for b in session.query(Book).filter_by(**dict_from_web)

will return the books that have the exact Title 'The Book' and the exact 
author 'Bob Smith'

MB

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[sqlalchemy] Re: Softcoding .filter(...)

[RVince]

Mark, yes, in part. What I cannot figure out -- and am not sure this
is possible with SQLAlchemy, is to go from strings, as returned from
HTTP Post's, representing the fields in the table (for the left side
of the relation) to the actual statemetn itself. In other words, if
the HTTP post calls for campring the Lastname column for equality to
the value smith, I can build the == 'smith' portfion, but how do I
Ibuild a String for the column name, into the value for that column
name so as to comport with SQLAlchemy's sytnax requirements. I don;t
think I can just have a query, q, and then say:
q = q.filter(lastname == 'smith')
can I? RVince

On Aug 12, 10:33 am, Mark Erbaugh m...@microenh.com wrote:
 On Aug 12, 2011, at 10:21 AM, RVince wrote:



  I'm trying to discern a means of creating a .filter(A rel B) where the
  values for A, rel and B come from an parameters passed in to the web
  page.

  I already have an SQLAlchemy statement, say
  query = Session.query(table).filter(A==B)

  and I want to be able to allow for a drilldown of sorts by the, such
  that from the web page they can pick a value from a dropdown, a
  relation (from a dropdown) and a textbox to compare to. But my problem
  is once I have these three values, how do I get them into
  the .filter() function? That's not going to merely accept string
  values -- is there a way to do this?

  Thanks, RVince

 You can build your SQLAlchemy queries dynamically, i.e.

 q1 = query.Session.query(table).filter(A == B)

 q2 = q1.filter(C == D)

 q3 = q2.filter(E == F)

 you could apply different relationships using conditional Python statements:

 if rel == 'eq':
         q4 = q3.filter(G == H)
 elif rel == 'neq':
         q4 = q3.filter(G != H)

 is this what you're looking for?

 Mark

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[sqlalchemy] Re: Softcoding .filter(...)

[NiL]

say you want to filter on the 'field' (field would be a string representing 
the name of the field) on objects of class == Klass

field_attr = getattr(Klass, field)

 would give you the instrumented attribute

then

Session.query(Klass).filter(field_attr == searchString)

or

Session.query(Klass).filter(field_attr.endswith(searchString))

would run

HTH

NiL

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Re: [sqlalchemy] Re: Softcoding .filter(...)

[Mark Erbaugh]

On Aug 12, 2011, at 11:52 AM, NiL wrote:

 say you want to filter on the 'field' (field would be a string representing 
 the name of the field) on objects of class == Klass
 
 field_attr = getattr(Klass, field)
 
  would give you the instrumented attribute
 
 then
 
 Session.query(Klass).filter(field_attr == searchString)
 
 or
 
 Session.query(Klass).filter(field_attr.endswith(searchString))
 
 would run
 
 HTH
 
 NiL

You can also use the class's __dict__ member:

field_attr = Klass.__dict__['field']

It really amazes me how Pythonic SQLAlchemy makes database access.

Mark



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Re: [sqlalchemy] Re: Softcoding .filter(...)

[Wichert Akkerman]

On 08/12/2011 05:52 PM, NiL wrote:
say you want to filter on the 'field' (field would be a string 
representing the name of the field) on objects of class == Klass


field_attr = getattr(Klass, field)

 would give you the instrumented attribute

then

Session.query(Klass).filter(field_attr == searchString)

or

Session.query(Klass).filter(field_attr.endswith(searchString))

would run


Alternatively if you are only interested in equality you can skip the 
getattr and use filter_by in combination with python's keyword argument 
handling:


Session.query(klass).filter_by(**{field: value})

Wichert.

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[sqlalchemy] Re: Softcoding .filter(...)

[RVince]

Wickert, can you give me an example ? I'm a little confused by this
posts of yours. RVince

On Aug 12, 12:20 pm, Wichert Akkerman wich...@wiggy.net wrote:
 On 08/12/2011 05:52 PM, NiL wrote:



  say you want to filter on the 'field' (field would be a string
  representing the name of the field) on objects of class == Klass

  field_attr = getattr(Klass, field)

   would give you the instrumented attribute

  then

  Session.query(Klass).filter(field_attr == searchString)

  or

  Session.query(Klass).filter(field_attr.endswith(searchString))

  would run

 Alternatively if you are only interested in equality you can skip the
 getattr and use filter_by in combination with python's keyword argument
 handling:

      Session.query(klass).filter_by(**{field: value})

 Wichert.

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[sqlalchemy] Re: Softcoding .filter(...)

[RVince]

Thanks to all you guys. Really. I didn't think I would be able to do
this! RVince

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