gistfile1.txt

[buildout]
extends =
    http://x.aclark.net/plone/4.1.x/develop.cfg
    http://good-py.appspot.com/release/dexterity/1.1

auto-checkout =
    collective.z3cform.datagridfield
    plone.app.relationfield
    collective.z3cform.datagridfield_demo

[sources]
collective.z3cform.datagridfield = git git@github.com:jaroel/collective.z3cform.datagridfield.git branch=origin/relationchoice-integration
plone.app.relationfield = git git@github.com:datakurre/plone.app.relationfield.git branch=origin/datagridfield-integration
collective.z3cform.datagridfield_demo = git git@github.com:jaroel/collective.z3cform.datagridfield_demo.git

[plone]
eggs +=
    ${buildout:auto-checkout}
    plone.app.dexterity
    collective.z3cform.datagridfield [test]

[omelette]
eggs =
    ${buildout:auto-checkout}
    plone.app.dexterity

[test]
eggs = ${plone:eggs}

Here's a buildout with tests passing:

[buildout]
extends =
    http://x.aclark.net/plone/4.1.x/develop.cfg
    http://good-py.appspot.com/release/dexterity/1.1

auto-checkout =
    collective.z3cform.datagridfield
    plone.app.relationfield
    collective.z3cform.datagridfield_demo

[sources]
collective.z3cform.datagridfield = git git@github.com:datakurre/collective.z3cform.datagridfield.git branch=relationchoice-integration
plone.app.relationfield = git git@github.com:datakurre/plone.app.relationfield.git branch=datagridfield-integration
collective.z3cform.datagridfield_demo = git git@github.com:jaroel/collective.z3cform.datagridfield_demo.git

[plone]
eggs +=
    ${buildout:auto-checkout}
    plone.app.dexterity
    collective.z3cform.datagridfield [test]

[omelette]
eggs =
    ${buildout:auto-checkout}
    plone.app.dexterity

[test]
eggs = ${plone:eggs}

I've used the [sources] mentioned and ran bin/test -s collective.z3cform.datagridfield.
All tests seem to pass.

Also in my Plone instance, the RelationValue values stored in the object now, instead of the objects!

Also i can reproduce the strange 'when is only one row there is no data' error in datagrid field. strange stuff

That's because of the hidden counter-field the widget depends on. I though it to be an independent issue from this relation stuff.

Yeah probably this is an independent issue.
Somehow i can't seem to reproduce this every time, will futher look in to this