riteshreddyr/flask-admin many-to-many search.md

## flask-admin many-to-many search.md

      
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              flask-admin many-to-many search.md
            
          
    #Flask-admin Many-to-Many Search
Many-to-Many searches are not easily supported by Flask-admin. Read Here for more info 
##Solution

Add the association tables to the list of join tables so that the join between the two tables can be made through the association table.
Reverse the tables to ensure that the association tables are processed before the other join table.

Tested on Flask-Admin 1.1.0
class Post( Base ):
    __tablename__ = 'posts'
    id = Column( Integer, primary_key=True )
    title = Column( Unicode( 255 ), nullable=False )
    tags = relationship( 'Tag', backref='posts', secondary='taxonomy' )

class Tag( Base ):
    __tablename__ = 'tags'
    id = Column( Integer, primary_key=True )
    name = Column( Unicode( 255 ), nullable=False )

taxonomy = Table(
    'taxonomy', Base.metadata,
    Column( 'post_id', Integer, ForeignKey( 'posts.id' ) ),
    Column( 'tag_id', Integer, ForeignKey( 'tags.id' ) ),
)

 class PostModelView( ModelView ):
        column_searchable_list = ( Post.title, Tag.name )
        column_filters = (Post.title, Tag.name)
        
        def init_search( self ):
            r = super( PostModelView, self ).init_search()
            #add the association table to search join list
            self._search_joins.append(taxonomy)
            #reverse the lsit so that the association table appears before the two main tables
            self._search_joins.reverse()
            return r
            
        def scaffold_filters(self, name):
            filters = super( PostModeView, self).scaffold_filters(name)
            #Check if "tags" table has been processed and the join table added
            if "tags" in self._filter_joins:
              #add the association table to the filter join tables
              self._filter_joins['tags'].append(taxonomy)
              #reverse the list so that the association table appears before the two main tables
              self._filter_joins['tags'].reverse()
            
            return filters