Re: how to write a custom renderer for any relationship ?

[Bruk Habtu]

Renderers have two methods you can override. render and render_readonly. You can have your custom renderer inherit the SelectFieldRenderer and override it's render_readonly method so that it returns a link.

http://docs.formalchemy.org/formalchemy/fields.html#selectfieldrenderer

def render_readonly(self, options=None, **kwargs):

    #build a dict

    if callable(options):

        L = options(self.field.parent)

    else:

        L = list(options)

    if len(L) > 0:

       if len(L[0]) == 2:

           L = [(v, k) for k, v in L]

       else:

           L = [(k, _stringify(k)) for k in L]    

    D = dict(L)

    links = []

    for key, val in D.iteritems():

        links.append("<a href='{0}'>{1}</a>".format(value, key))

    return '<br/>'.join(links)

Just quickly wrote that up, not sure if it works or not as I am at work and dont have time to test it but that should give you an idea of what to do. 

As for a default renderer, there doesn't look like there is a ForeignKey key you can use. The keys available are column types and don't include constraints.

On Friday, 26 October 2012 10:17:15 UTC-4, pca wrote:

Hi,

I'm trying to write a simple admin site for the cherrypy web framework.  I wish to show foreign keys as a list box in edit mode (easy), and as a link to another admin web page in read-only mode (very hard !).  I would think that this is a very common requirement, but I still can't find a way to do it with formAlchemy in a generic way. Could someone help ?

The basic program outline is as follows.  Let's say I have 2 tables A and B, and A.b_id is a foreign key to B.id

class A(Base):

    __tablename__ = 'A'

    id = Column(Integer, primary_key=True)

    b_id = Column(Integer, ForeignKey('B.id''))

    b = relationship("B")

class B(Base):

    __tablename__ = 'B'

    id = Column(Integer, primary_key=True)

   

a = session.query(A).filter(id == 123).first()

fs = FieldSet(a)

fs.readonly = True # or false

print fs.render()

a.b is an instance of the B class : it is rendered as a list box in edit mode, and as a string in readonly mode.

How to render a.b as an HTML link in readonly, while keeping it as a list box in edit mode ?  How to do this in a generic way, for any relationship ?  I have tried to add a custom renderer to the DefaultRenderers dictionary, but which key should I use for a relationship renderer ?

Thanks in advance.

Pierre C.