I have a user model field with choices asking about employment, if person select the choice employed then only I want to show fields asking about employer details in user inerface, any possibilities? Thank you in advance.
django's native forms do not, by default, have this ability. this is generally accomplished by adding the appropriate client-side controls into the form's template; e.g. using javascript to show/hide some fields based on another field's value. this is commonly accomplished using javascript or in some cases even pure css.
if you're dealing with a multi-step form across multiple pages or if you know in advance what the value that might include/remove fields is, you can override the form's __init__ method to manipulate its self.fields property to add or remove fields as desired when the form is initially being generated.
good luck!
Related
Recently I've been developing a Django website, which includes the owner being able to add content with descriptions etc.
The problem I'm having is: How can I make the fields support multiple languages? (3 in this case)
The approach I tried was: Creating a model with 3 text fields, have my content model take that model as a foreign key. This sort of works, but now I would have to create all the descriptions first, separately, before creating the actual object it is being used by. This is, in my opinion, a bad idea.
What I would like to be able to do, is to have 3 text fields in the model which is actually using those 3 text fields' admin page, but without actually having 3 text fields in that model.
Using inlines would work, but I'd have to make my multilanguage textfield model have a foreign key to my content model, instead of the other way. This would mean the multilanguage model works for only other model type.
So, to clear the question up:
How can I have a TextField and a CharField support multiple languages?
How can I show the ForeignKey's target model's creation widget in it's owner's admin page?
How can I use inlines, without locking the inline to just one model type?
How can I make a model act like a field?
How can I write a custom TextField?
Answering any of those will be enough for me to solve my problem.
Thanks.
There is too many questions and the docs is at your reach... I'll just answer the easiest one you should have search for by yourself.
How can I have a TextField and a CharField support multiple languages?
You should have a look to i18n here
How can I write a custom TextField?
Have a look to custom Fields
What is the defacto way of creating model relationships in Django via frontend forms.
For example a user signs up for service using a form, they start a quote.
In getting a quote they can select and add products to their quote specifying variable such as sizes in this process.
This is modelled with relevant User, Quote, Product models and relevant relationships.
I am trying to work out the best way that these are linked together by frontend forms and views.
Would I load into the quote form a hidden field for the related user_id for example, which I can then process manually to form the one-to-many relationship.
I am just wondering if this is something accounted for within forms or if I have to manually create the forms to achieve my goal.
This is one of the more complicated things to try and achieve but there are several things in Django which will help you.
You're going to need a ManyToMany field on the Quote model to link the Products to it.
This can be displayed in forms simply via a ModelMultipleChoiceField:
https://docs.djangoproject.com/en/dev/ref/forms/fields/#modelmultiplechoicefield
... which is just renders a basic multiple select list of existing products.
The interface you want probably looks more like an inline formset however. The complication here is that they are designed for ForeignKey relations rather than ManyToMany.
Under the covers, a ManyToMany relation is actually just two ForeignKey relations, via an intermediate 'through' model. We can exploit this to build an inline formset on the through model, see this answer:
https://stackoverflow.com/a/10999074/202168
You'll note the caveat in that answer, the inline rows won't know which Quote they belong to unless you override some code.
You may like to look at some helper apps which provide custom widgets for ManyToMany fields:
https://code.google.com/p/django-ajax-filtered-fields/
http://django-autocomplete-light.readthedocs.org/en/latest/
Just curious. What is the best practice for when to use form vs model validation?
From what I understand currently, form validation should be used for:
AJAX / HTTP requests params
Forms that do not correlate to a model?
Another question is: I have a HTML form that roughly correlates to a model instance, do I use a ModelForm for it?
Definitely use ModelForm, if your form resembles model object even in a tiny bit.
If there are some minor differences (e.g. you don't use some of the fields or you want to use different error messages etc.) it's much easier to customize ModelForm then to use Form and implement all this functionality from scratch.
For more reference regarding ModelForm please checkout PyDanny's Core Concepts of Django ModelForms.
I am also trying to understand what is the difference/relation between form and model validation and I would like to share my notes that are formed after reading several docs.
I am currently interested in Creating Forms from Models
#mariodev shared the document Core Concepts of Django ModelForms and this provided a good start.
ModelForms select validators based off of Model field definitions
The main story behind the scenes seems to be the DRY principal. This article explains very well what exactly is the case here.
All right, all this is fair. The question is "Where in the Django Documentation is this explained"?
I bumped on a very brilliant article where it states that:
The form.full_clean() method is called by django at the start of the validation process (by form.is_valid(), usually immediately after the view receives the posted data).
Correct me if I am wrong but that line reads that everytime I enter data and hit 'enter' the validation process begins!
OK, this is simple now:
The validation on a ModelForm begins when we hit 'enter'.
Django first validates the form by checking one by one every applicable validation method on Fields, Field Subclasses (This is the documentation for a model's field subclass, not for a form field subclass), Form Subclasses and ModelForm (since it is a ModelForm).
Finally, it validates the Model Instance.
This is how all this works theoretically. The only thing that remains is to implement it.
What is the best way to include in a model to save multi-select US states? I need a user to select several states and save this data in a model (via form OR modelform ).
I tried LocalFlavor USStateField model it doesn't seem to work for me since I can't call it like a regular model.
This django app i've written may help you.
Django: what approaches are there to 'parametising' the display and editability of form fields.
I have several forms where I want some fields to be simply missing from the form display (dependent on the current user) and some fields to be uneditable, depending on the user.
This needs to be enforced on the server, so that a malicious user cannot break the security by manually constructing a post request with the missing parameter.
Likewise fields which are not displayed to the user, must still come back in the form results, so that fields which are not displayed to a user and not 'wiped-out' when the model is written back to the DB.
I also need to solve the same hiding problem for templates.
The app will have dozens of forms, with different immutability/hiding requirements, so this needs to be a generic system. Coding permissions inside each form would be too prone to error.
Any help appreciated.
Chris.
For hidding fields from form display, simple delete unneeded fields in form's __init__ method. Constructing post request by adding deleted fields, will not have influence on the form.
Regarding disabled or readonly fields, check this article and another question. Basically, cleaning field should set it to initial state.