Databases
StackOverflow2013
Postsdbo
POfiltering by association attributes with SqlAlchemy association_proxy
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POfiltering by association attributes with SqlAlchemy association_proxy
    primarykey
    data
    text
    <p>I have a <em>many-to-many</em> (developers &amp; projects) relationship modeled using SA's <em>association_proxy</em>. The collections (developers on each project &amp; projects for each developer) work fine, but I need to filter on an attribute of the association itself (status). Something like this (which does not work):</p> <pre><code>activeDevelopers = s.query(Developer).filter_by(Developer.developerProjects.status == 'active').all() </code></pre> <p>What am I missing? Here is the complete test code:</p> <pre><code>import logging from sqlalchemy import create_engine, Table, Column, Integer, String, MetaData, ForeignKey from sqlalchemy.orm import relation, mapper, sessionmaker from sqlalchemy.sql import * from sqlalchemy.ext.associationproxy import association_proxy log = logging.getLogger('nm_test') logging.basicConfig(level=logging.DEBUG, format='%(asctime)s,%(msecs)03d %(levelname)s [%(filename)s.%(funcName)s @ %(lineno)d.%(thread)d] %(message)s') engine = create_engine('sqlite:///:memory:', echo = False, echo_pool = False) meta = MetaData() meta.bind = engine developer_table = Table('developer', meta, Column('id', Integer, primary_key=True, autoincrement = False), Column('name', String), ) project_table = Table('project', meta, Column('id', Integer, primary_key=True, autoincrement = True), Column('name', String) ) developer_project_table = Table('developer_project', meta, Column('developer_id', Integer, ForeignKey('developer.id'), primary_key = True), Column('project_id', Integer, ForeignKey('project.id'), primary_key = True), Column('status', String) ) class Developer(object): projects = association_proxy('developerProjects', 'projects') def __str__(self): return 'Developer id:%i, name:%s' % (self.id, self.name) class Project(object): developers = association_proxy('developerProjects', 'developers') def __str__(self): return 'Project id:%i, name:%s' % (self.id, self.name) class DeveloperProject(object): def __str__(self): return 'DeveloperProject developer:%s, project:%s, status:%s' % (self.developer_id, self.project_id, self.status) mapper(Developer, developer_table, properties = { 'developerProjects':relation(DeveloperProject, backref = "developers") }) mapper(Project, project_table, properties = { 'developerProjects':relation(DeveloperProject, backref = "projects") }) mapper(DeveloperProject, developer_project_table) meta.create_all(engine) conn = engine.connect() conn.execute(project_table.insert(),[ {'name':'stackoverflow'}, {'name':'superuser'}, ]) conn.execute(developer_table.insert(),[ {'name':'John'}, {'name': 'TerryJ'}, {'name': 'TerryG'}, {'name': 'Eric'}, {'name': 'Graham'}, ]) conn.execute(developer_project_table.insert(),[ {'developer_id':1, 'project_id':1, 'status':'active'}, {'developer_id':2, 'project_id':2, 'status':'inactive'}, {'developer_id':3, 'project_id':2, 'status':'active'}, {'developer_id':4, 'project_id':1, 'status':'active'}, {'developer_id':4, 'project_id':2, 'status':'active'}, {'developer_id':5, 'project_id':1, 'status':'active'}, {'developer_id':5, 'project_id':2, 'status':'inactive'}, ]) Session = sessionmaker(bind=engine) s = Session() developers = s.query(Developer).all() projects = s.query(Project).all() for d in developers: log.debug(d) for p in d.projects: log.debug(' %s' % p) for p in projects: log.debug(p) for d in p.developers: log.debug(' %s' % d) # does not work activeDevelopers = s.query(Developer).filter_by(Developer.developerProjects.status == 'active').all() # AttributeError: Neither 'InstrumentedAttribute' object nor 'Comparator' object has an attribute 'status' </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USNima Soroush
    1. USHollister
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POfiltering by association attributes with SqlAlchemy association_proxy
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POfiltering by association attributes with SqlAlchemy association_proxy
      1. USWayne
      1. VTFavorite
    3. VO
      singulars
      1. POfiltering by association attributes with SqlAlchemy association_proxy
      1. This table or related slice is empty.
      1. VTUpMod
    1. This table or related slice is empty.
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload