Probable issue on proxy submodels and polymorphic inlines

[marcoooo]

Hi, I am facing a problem with my polymorphic inlines:
Here is my class hierarchy:

class BaseParam(PolymorphicModel):
    somefields...
    submission = models.ForeignKey(....)
class TextParam(BaseParam):
    """ Standard text input """
    class Meta:
        proxy = True

class BooleanParam(BaseParam):
    ...concrete subclass
class DecimalParam(BaseParam):
    ...concrete subclass
class IntegerParam(BaseParam):
    ...concrete subclass
class ListParam(BaseParam):
    ...concrete subclass
class FileInput(BaseParam):
    ...concrete subclass

I used in the "SubmissionAdmin" polymorphic inlines as follow:

class PolymorphicInputInlineChild(StackedPolymorphicInline.Child):
    ...just override formfield_for_foregeinley for another relation field in main BaseParam class


class SubmitInputsInline(StackedPolymorphicInline, CompactInline):
    class BooleanParamInline(PolymorphicInputInlineChild):
        model = BooleanParam
        exclude = ['order']
        classes = ['collapse']

    class ListParamInline(PolymorphicInputInlineChild):
        model = ListParam
        exclude = ['order']

    class DecimalParamInline(PolymorphicInputInlineChild):
        model = DecimalParam
        exclude = ['order']

    class IntegerParamInline(PolymorphicInputInlineChild):
        model = IntegerParam
        exclude = ['order']

    class TextParamInline(PolymorphicInputInlineChild):
        model = TextParam
        exclude = ['order']

    class FileInputInline(PolymorphicInputInlineChild):
        model = FileInput
        exclude = ['order']

    model = BaseParam
    exclude = ['order']
    verbose_name = "Param"
    verbose_name_plural = "Params"
    classes = ['collapse', ]
    child_inlines = (
        TextParamInline,
        FileInputInline,
        BooleanParamInline,
        ListParamInline,
        IntegerParamInline,
        DecimalParamInline,
    )
    list_display_links = None
    list_display = ('name', '__class__', 'default')

And finally my main modelAdmin:

class ServiceSubmissionAdmin(PolymorphicInlineSupportMixin, WavesModelAdmin):
    """ Submission process administration -- Model Submission """
    class Media:
        ...
    inlines = [
        SubmitInputsInline,
        ... other non polymorphic inlines
    ]

For all non-proxy subclasses, everything works well, but in case I wan to add a TextParam, upon save I got this error:

ValidationError at /admin/waves/submission/1/change/
[u"Child model type <class 'waves.models.inputs.BaseParam'> is not part of the formset"]

Is this a configuration issue ? Am I missing an important point ? of should I replace model class in TextParam Inline to BaseParam, and lost possibilyt to filter my future queryset for this sub-class ?

[marcoooo]

For memory, i found a 'quick and dirty' workaround for this problem (just to be able to save in database a new object from proxy class). I declare a modelForm associated with my 'proxy' Inline, and then override save() method to cast to the right subclass. Seems to do the work so far.
So with this solution, drop down menu to select subclass display the baseclass verbose_name , so if there is more than one direct proxy subclass, this workaround may not be easy to deal with..still I can now save my proxy models in admin.

class TextParamForm(forms.ModelForm):
    class Meta:
        model = TextParam
        exclude = ['order']

    def save(self, commit=True):
        self.instance.__class__ = TextParam
        return super(TextParamForm, self).save(commit)
...
class SubmitInputsInline(StackedPolymorphicInline):
    ...
    class TextParamInline(PolymorphicInputInlineChild):
        model = BaseParam
        exclude = ['order']
        form = TextParamForm
   ...
...