form.is_valid() always returning false

Model class

class Fuzz_Engine(models.Model):
    id = PositiveTinyIntField(primary_key = True)
    engine_name = models.CharField(max_length=16)
    version = mo开发者_JAVA百科dels.CharField(max_length = 16)

    class Meta:
        db_table = 'fuzz_engine'
        unique_together = ('engine_name', 'version')

class AddFuzzEngineForm(ModelForm):
    class Meta:
        model = Fuzz_Engine

View Class

def addengine(request)
    if request.method == 'POST':
        form = AddFuzzEngineForm(request.POST)

        # input validation for add phone model form
        if form.is_valid():
            fuzzEngineToAdd = Fuzz_Engine (engine_name = request.POST['engine_name'], version = request.POST['version'])
            fuzzEngineToAdd.save(force_insert=True)

            return render_to_response('fuzz/fuzz_cengine_results.html', {'fid': fuzzEngineToAdd.id,'fe': fuzzEngineToAdd,},context_instance=RequestContext(request))
    else:
        form = AddFuzzEngineForm()

    return render_to_response('fuzz/add_fuzz_engine.html', {'form': form},context_instance=RequestContext(request))

I have looked into a few similar questions on this issue, tried to print out the errors but doesn't seem to appear.

Django Formsets - form.is_valid() is False preventing formset validation form.is_valid() always returning false

I have a feeling that the cause of the error lies in the structure of my model form class.

The .is_valid is false as I have placed a code in that if statement and it doesn't run, however if I have an else statement(which is not here) for if it is not valid, it will appear.

Can anyone provide another way of debugging this kind of error?

---

Couple of issues, it's hard to debug the code if the code you paste in isn't formatted well. The indentations were a mess so I'm not sure if that's causing a problem.

It seems like you are manually assigning a foreign key for your model. I would suggest just letting django handle the id for the model:

class Fuzz_Engine(models.Model):
    engine_name = models.CharField(max_length=16)
    version = models.CharField(max_length = 16)

    class Meta:
        db_table = 'fuzz_engine'
        unique_together = ('engine_name', 'version')

Your form looks fine:

class AddFuzzEngineForm(ModelForm):
    class Meta:
        model = Fuzz_Engine

Some problems I see in your views include:

1. you shouldn't use request.POST['field_names'] directly. you should be getting the cleaned_data from your form.

2. you can save the form directly because it is a ModelForm. if you need the instance that you just created, that is what is returned from the save method, you can set a variable and use that as shown below.

   def addengine(request)
       if request.method == 'POST':
           form = AddFuzzEngineForm(request.POST)
   
           if form.is_valid():
               instance = form.save()
               return render_to_response('fuzz/fuzz_cengine_results.html', {'fid': instance.id,'fe': instance,},context_instance=RequestContext(request))
       else:
           form = AddFuzzEngineForm()
   
       return render_to_response('fuzz/add_fuzz_engine.html', {'form': form},context_instance=RequestContext(request))
   

3. With your original view, it looks like you are trying to save a Fuzz_Engine instance with no id.

---

DTing has some great points, but I suspect your actual problem is related to your explicit definition of the id field on your model. Unless you have a really good reason, you should never do this - Django defines an autoincrement field automatically, and there is rarely any point overriding this, unless you are using a legacy db that can't be changed.

In your case, you have defined it as a tinyint without autoincrement. That means that field is going to be required on any form, as it needs to be specified manually every time you create a new instance. You haven't shown the template you're using to display the form so it's impossible to be sure, but I imagine you're not showing this field at all.

If you really really want to carry on doing it this way, you will need to specify exclude = ('id',) on the form Meta. Then in your is_valid clause, taking on board DTing's recommendations, you'll need to do this:

if form.is_valid():
    instance = form.save(commit=False)
    instance.id = some_function_for_calculating_id()
    instance.save()

But as I say, you shouldn't be doing that at all.