I have a model with many fields. I need to run a code only when two specific fields are changed. I know I can modify my model's save() method but I don't know how to check which fields are changed in my ModelForm.
Sorry because i cant give you any code snippet since i am not very experienced in Django, but i would go for getting a signal when a change is done through a controler class listening on the models and hearing for changes. Hope i might helped a bit.
Good luck
Django-model-utils has something called a FieldTracker that does exactly this. Just instantiate it in your model and tell it to track the specific fields you're looking for. Then you can use the has_changed method to test if a given field has changed since the last save.
This package has some other great utilities as well, I really recommend looking through the docs.
You could try django-dirtyfields.
Related
I'm trying to check if a model exists in the PredictionEnginePool by calling predictionEnginePool.GetModel(modelName: "ModelA") but I get an exception saying the model is not in the Dictionary even though I pass in the correct model name specified during creation.
Is this the right way to look for a model or is there a better way?
CEO, I don't think there's currently a way to check if a model has been loaded or not. I recommend submitting an issue as a suggestion to the ML.NET repo. https://github.com/dotnet/machinelearning
Has anyone experience issues with this but in Django-piston that doesn't allow you to override fields already set?
https://bitbucket.org/jespern/django-piston/issue/192/object-handler-fields-override-local-field
Can anyone help me with a work around? I saw there is an easy patch but I don't want to go in and change the code in piston. Is there a way around it?
I'm using django-piston for quite a long time. There are a couple of issues with when you specify model = Foo. I simply use it to organize web service's urls, OAuth and Django Authentication. I still dont have any issue with it (yet). If you dont have any special reason to use model = Foo and fields I think you can call the model within read and create.
Hope it help :)
If you dont want to apply the patch yourself, and you dont want to avoid using certain model references on handlers to work around the issue, then maybe just clone the fork of piston that contains the patch being pushed to the main repo:
https://bitbucket.org/rptirrell/django-piston/overview
Its up to date aside from that and its trivial to swap it out to the main repo whenever you want.
Before I start on this project I want make sure what I am proposing is feasible. There is an unusual requirements I have to satisfy.
The model and formModel fields have to support a comment field on every field. I would like to be able to access them by object.field and object.field.comment. At first glance, this looks like I should have a separate type of comment and then somehow link it to correct field but is there a way to create a custom modelField that stores data in more then one database field from one or more form inputs? I would think there would have to be a custom widget to support this too?
If anyone has any ideas or examples of anything like this please respond.
I think this is the answer to my question. I have not tried it yet, but from the description it looks like what I need. https://docs.djangoproject.com/en/dev/ref/forms/widgets/#multiwidget
I'm customizing the comments model per the Django documentation.
In my specific use case, however, comments are allowed to be blank. The trouble I get into then is that the Comment model is setup with an unique_together:
unique_together = [('user', 'comment', 'flag')]
Any ideas on how I could go about overriding this?
(...or did I start off on the wrong track with using the Comments framework altogether? :)
Doesn't look like the Comment model has a unique constraint.
Code for models.py for contrib.comments.
It looks like the CommentFlag model has the uniqueness constraint which shouldn't effect you having blank comments.
Your problem must lie elsewhere.
I'm not very familiar with the comments app but here are some ideas you can look at to get around your problem.
Warning I haven't used either of these methods on the comments app so I'm not sure if using these will break any downstream functions of the comments framework. Be sure to look into/test if you decide to use either of these.
That being said, I can think of 2 ways you can approach this.
Override the unique together:
class NonUniqueComment(Comment):
class Meta(Comment.Meta):
unique_together = []
Make the comments field store Null instead of empty string in the db.
Would it be possible/best practice to use 1 FormWizard for manipulating multiple models?
I've experimented with the FormWizard and have defined all the forms. The page 'flow' itself works like a charm. However with all the checks that need to be done and Models that are manipulated it feels like I'm sticking code in the form's __init__ and/or process_step() that really belongs in views.py. The docs even state: "Dont manipulate form data via process_step().
Testing a concept with everything in one view, thus using a last_submitted_page (the step equiv) it feels like I'm writing another formwizard.
Anybody been here before? Tips welcome.
Thanx a lot.
Regards,
Gerard.
Zooming out on the issue I decided to go for the FormWizard approach. I re-confirmed that code is easily placed in forms.py and that you can get your model info by using. the process_step().
GrtzG