如何根据django admin中的另一个选项字段限制选择字段选项

Question

I have the following models:

class Category(models.Model):
    name = models.CharField(max_length=40)

class Item(models.Model):
    name = models.CharField(max_length=40)
    category = models.ForeignKey(Category)

class Demo(models.Model):
    name = models.CharField(max_length=40)
    category = models.ForeignKey(Category)
    item = models.ForeignKey(Item)

In the admin interface when creating a new Demo, after user picks category from the dropdown, I would like to limit the number of choices in the "items" drop-down. If user selects another category then the item choices should update accordingly. I would like to limit item choices right on the client, before it even hits the form validation on the server. This is for usability, because the list of items could be 1000+ being able to narrow it down by category would help to make it more manageable.

Is there a "django-way" of doing it or is custom JavaScript the only option here?

Answer 1

Here is some javascript (JQuery based) to change the item option values when category changes:

<script charset="utf-8" type="text/javascript">
  $(function(){
    $("select#id_category").change(function(){
      $.getJSON("/items/",{id: $(this).val(), view: 'json'}, function(j) {
        var options = '<option value="">--------&nbsp;</option>';
        for (var i = 0; i < j.length; i++) {
          options += '<option value="' + j[i].optionValue + '">' + j[i].optionDisplay + '</option>';
        }
        $("#id_item").html(options);
        $("#id_item option:first").attr('selected', 'selected');
      })
      $("#id_category").attr('selected', 'selected');
    })
  })
</script>

You need a view to be called on the /items/ URL that supplies a JSON list of the valid items.

You can hook this into your admin by using model admin media definitions .

Answer 2

There is django-smart-selects :

If you have the following model:

class Location(models.Model)
    continent = models.ForeignKey(Continent)
    country = models.ForeignKey(Country)
    area = models.ForeignKey(Area)
    city = models.CharField(max_length=50)
    street = models.CharField(max_length=100)

And you want that if you select a continent only the countries are available that are located on this continent and the same for areas you can do the following:

from smart_selects.db_fields import ChainedForeignKey 

class Location(models.Model)
    continent = models.ForeignKey(Continent)
    country = ChainedForeignKey(
        Country, 
        chained_field="continent",
        chained_model_field="continent", 
        show_all=False, 
        auto_choose=True
    )
    area = ChainedForeignKey(Area, chained_field="country", chained_model_field="country")
    city = models.CharField(max_length=50)
    street = models.CharField(max_length=100)

Answer 3

我认为JavaScript / AJAX将是解决此问题的最佳方法。

Answer 4

You will need to have some kind of non-server based mechanism of filtering the objects. Either that, or you can reload the page when the selection is made (which is likely to be done in JavaScript anyway).

Otherwise, there is no way to get the subset of data from the server to the client.