Question

I have two models “milestone” and “project”, the code as below:

class Project(models.Model):
    ID = models.CharField(max_length=15, primary_key=True)
    Name = models.CharField('Project Name', max_length=100)
    ShortName = models.CharField('Project Short Name', max_length=100)
    def __unicode__(self):
        return self.Name

class Milestone(models.Model):
Project = models.ForeignKey(Project)
def __unicode__(self):
    return self.Name

When i create a milestone, i can select a project and then the milestone belongs to that project, for example, project1---> m1; project2 --->m2
Then in an other model “Task”, i want to create a task belong to a special project and milestone. The code is as below:

class Task(models.Model):
    Name = models.CharField('Title', max_length=200)  
    Project = models.ForeignKey(Project,null=True, blank=True)
    Milestone = models.ForeignKey(Milestone,null=True, blank=True)
    def __unicode__(self):
        return self.Name

The problem is that when i create a Task and select a project, then the itemlist of the milestone field is always including two “m1” and “m2”, i want that when i select project1 the list only show m1, and when i select project2 the list only show m2.

How can i implement this? Thanks

Updated
My folder structure

 mysite_new/

      manage.py
      mysite/
      ------ __init__.py
             urls.py
             setting.py
             wsgi.py
             templates/
                      default.html

      ticket/
      ------__init__.py
            models.py
            view.py
            urls.py
            admin.py
            js/
              ---- project_change.js

in admin.py

class TaskAdmin(admin.ModelAdmin):
    class Media:
          js = ['js/project_change.js',]
admin.site.register(Task,TaskAdmin)

In urls.py

    urlpatterns = patterns('',
    url(r'^admin/', include(admin.site.urls)),
    url(r'^admin/login', MyView().login),

    url(r'^hello/', hello),
    (r'^product_change/','project_choices'),


)

And in my db

In the add task web site:http://127.0.0.1:8000/admin/ticket/task/add/

I don’t change any of your code, could you please help to check what is the wrong with my code ?

Update
Thanks very much. Arulmurugan, a kind-hearted man

Answer 1

You achieve this using jQuery and Ajax. Try using the following:

project_change.js

(function($){   
    $(function(){
        $(document).ready(function() {
            $('#id_Project').bind('change', project_change);            
            $('#id_Milestone > option').show();
            if ($('#id_Project').val() != '') {
                var project_id = $('#id_Project').val();
                $.ajax({
                "type"      : "GET",
              "url"         : "/product_change/?project_id="+project_id,
                "dataType"  : "json",
              "cache"       : false,
                "success"   : function(json) {
                    $('#id_Milestone >option').remove();
                    for(var j = 0; j < json.length; j++){
                        $('#id_Milestone').append($('<option></option>').val(json[j][0]).html(json[j][1]));
                    }
                }           
            });
            }
        });
    });  
})(django.jQuery);

// based on the project, milestone will be loaded

var $ = django.jQuery.noConflict();

function project_change()
{
    var project_id = $('#id_Project').val();
    $.ajax({
    "type"      : "GET",
  "url"         : "/product_change/?project_id="+project_id,
    "dataType"  : "json",
  "cache"       : false,
    "success"   : function(json) {
        $('#id_Milestone > option').remove();
        for(var j = 0; j < json.length; j++){
            $('#id_Milestone').append($('<option></option>').val(json[j][0]).html(json[j][1]));
        }
    }           
})(jQuery);
}

Include the following in views.py:

from django.shortcuts import HttpResponse
from django.utils import simplejson

from ticket.models import Milestone

def project_choices(request): 
    milestone_list = []
    project_id = request.GET.get('project_id')
    milestones = Milestone.objects.filter(project = project_id)    
    [milestone_list.append((each_milestone.pk,each_milestone.name)) for each_milestone in milestones]
    json = simplejson.dumps(milestone_list)
    return HttpResponse(json, mimetype='application/javascript')

In urls.py:

from ticket.views import project_choices

urlpatterns = patterns(
    (r'^product_change/', project_choices),
)

In admin.py where you want to load milestone based on project:

class Media:
    js = ['/path/to/project_change.js',]

I hope this will help you.