Django custom validation of multiple fields in a form

django, django-forms

Solution

Store the errors and don't raise them until the end of the method:

def clean(self):
    span = self.cleaned_data['span']
    max_span = self.cleaned_data['max_span']
    piece = self.cleaned_data.['piece']
    error_messages = []

    # validate piece 
    try:
        Piece.objects.get(pk=m)
    except Piece.DoesNotExist:
        error_messages.append('Illegal Piece selected')
        self._errors["piece"] = "Please enter a valid model"

    # validate spans
    if span > max_span:
        error_messages.append('Span must be less than or equal to Maximum Span')
        self._errors["span"] = "Please enter a valid span"

    if len(error_messages):
        raise forms.ValidationError(' & '.join(error_messages))

    return self.cleaned_data

Problem

for which I want to validate a number of fields in a custom clean method. I have this so far: ``` class ProjectInfoForm(forms.Form): module = forms.ModelChoiceField( queryset=Module.objects.all(), ) piece = forms.CharField( widget=forms.Select(), required=False, ) span = forms.IntegerField( max_value=100, initial=48 ) max_span = forms.IntegerField( max_value=100, initial=0 ) def clean(self): span = self.cleaned_data['span'] max_span = self.cleaned_data['max_span'] piece = self.cleaned_data.['piece'] # validate piece try: Piece.objects.get(pk=m) except Piece.DoesNotExist: raise forms.ValidationError( 'Illegal Piece selected!' ) self._errors["piece"] = "Please enter a valid model" # validate spans if span > max_span: raise forms.ValidationError( 'Span must be less than or equal to Maximum Span' ) self._errors["span"] = "Please enter a valid span" return self.cleaned_data ``` However, this only gives me one of the messages if both clauses invalidate. How can I get all the invalid messages. Also I do not get the field-specific messages - how do I include a message to be displayed for the specific field? Any help much appreciated.

Original source