# django-cascading-dropdown-widget
Provide a cascading-dropdown widget for django.
## Install
```shell
pip install django-cascading-dropdown-widget
```
## Usage
**pro/settings.py**
**Note:**
- The application used template of django_cascading_dropdown_widget, so MUST include django_cascading_dropdown_widget in INSTALLED_APPS.
```python
INSTALLED_APPS = [
...
'django_cascading_dropdown_widget',
...
]
```
**app/admin.py**
**Note:**
- Create a new ModelForm, and setting field widget to DjangoCascadingDropdownWidget.
- Create a choices generator instance.
```python
from django.contrib import admin
from django_cascading_dropdown_widget.widgets import DjangoCascadingDropdownWidget
from django_cascading_dropdown_widget.widgets import CascadingModelchoices
from django import forms
from .models import Category
from .models import Book
from .models import Character
class CharacterForm(forms.ModelForm):
class Meta:
model = Category
exclude = []
widgets = {
"book": DjangoCascadingDropdownWidget(choices=CascadingModelchoices({
"model": Category,
"related_name": "books",
},{
"model": Book,
"fk_name": "category",
})),
}
class CharacterAdmin(admin.ModelAdmin):
form = CharacterForm
list_display = ["name", "book"]
```
## Choices generator
### CascadingModelchoices
```python
class CascadingModelchoices(object):
def __init__(self, *cascadings):
...
```
The parameters for CascadingModelchoices generator are the CASCADING-MODEL-SETTINGS(name it cascadings for short). A MODEL-SETTING(name it cascading for short)'s config items are:
- model, required. The Model class.
- related_name, required but except for the last model-setting. Use the related_name to get the queryset of the next level items.
- fk_name, required but except for the first model-setting. Which field name to get parent model.
- empty, optional. Use *empty* string instread of '----- xxx ----' in select for empty value.
- str, optional. Get item title from *str* method or property instread of get title by *str(item)*.
### SimpleChoices
### SimpleChoices2 (alias)
```python
class SimpleChoices(object):
def __init__(self, *cascadings, empty1="-"*10, empty2="-"*10):
...
```
- A cascading is a tuple of (Title1, List).
- The Title1 is the first level option.
- The List is the second level selector. The List item is a tuple of (Value2, Title2).
- The Value2 is the second level option's value.
- The Title2 is the second level option's title.
### MPTTModel Choices
- Use CascadingModelchoices for the generator.
- Create *indented_title* function for the MPTTModel. You use whatever name for the *indented_title*.
```
class MyModel(MPTTModel):
def indented_title(self):
return ("-"*4) * self.get_level() + self.name
```
- Setting ```"str": "indented_title"``` in cascading.
- The application django-cascading-dropdown-widget is NOT required django-mptt, so install django-mptt by youself. We have did try...except... with django-mptt's missing.
## Releases
### v0.2.6 2021/04/08
- Fix problems that sometimes the init change event is not triggered.
### v0.2.5 2020/12/01
- Remove arrive.js deps.
- Use django's jquery.
- Fix change event first trigger problem. We should ignore the first trigger.
### v0.2.2 2020/03/27
- Use `$(document).on("change", ".django-cascading-dropdown-widget-select", function(){...})` instead of `arrive` monitor. So now we do NOT depends on django-static-arrive.
### v0.2.1 2020/03/25
- Use django-static-arrive js file.
- Fire change event on the hidden input.
### v0.2.0 2020/03/23
- Add SimpleChoices generator.
- Add `white-space: nowrap;` for django-cascading-dropdown-widget.
### v0.1.0 2020/03/16
- Fisrt release.