Question

Here is how my models are setup:

class ModelA(models.Model):
    user = models.ForeignKey(User)
    modelB = models.ForeignKey('ModelB', related_name='modelB')
    # more fields here

class ModelB(models.Model):
    user = models.ForeignKey(User)
    # more fields here

The user field in both classes are just so that both of these can be queried by the same user later on.

I have a ModelForm of ModelB and I would like to have the users be able to fill out a ModelB ModelForm with a dynamic number of ModelA instances. I would like ModelB’s form to start out with 1 instance of ModelA to fill out and then the user should be able to add more ModelA’s to ModelB’s form.

I’m stuck on this as a personal project and would really like to move forward. Thanks for any help!

Edit 1: I know that I will most likely need to do some work by overloading ModelForms def __init__, but that is about as far as I have gotten. Also I am using ClassBasedGeneric Views (CreateView to get the add working and an EditView later on), but I am willing to move away from that if needed.

Answer 1

You require django inline formset

In view:

f_set = inlineformset_factory(ModelB, ModelA, extra=1)

In template lets suppose you are rendering form_set in a div whose id is one_to_many:

<form>
   <div id="one_to_many">
       {{f_set.as_table}}
   </div>
</form>

#This will render some thing like this
<form>
    <div id="one_to_many">
        <table>
            <tr>
               <th>
                   <label for="id_form-0-field_name">Field Name:</label>
               </th>
               <td>
                  <input id="id_form-0-field_name" type="text" name="form-0-field_name" value="" maxlength="100" />
                  <input type="hidden" name="form-0-id" value="1" id="id_form-0-id" />  
                </td>
            </tr>
        </table>
        <input type="button" value="Add More Field" id="add_more">
    </div>
</form>

Now the jquery part to add field dynamically:

$(document).ready(function(){
        $('#add_more').click(function(){
            var tbl = $('#one_to_many').children('table');
            var last_id = parseInt(tbl.find('input[type=hidden]').last().val());
            var next_id = last_id + 1;
            htm = '<tr><th><label for="id_form-'+last_id+'-field_name">Field Name:</label></th><td><input id="id_form-'+last_id+'-field_name" type="text" name="form-'+last_id+'-field_name" value="" maxlength="100" /><input type="hidden" name="form-'+last_id+'-id" value="'+next_id+'" id="id_form-'+last_id+'-id" /></td></tr>'
            tbl.find('tr').last().after(htm);

        });    
    });

You can test this on jsfiddle. Note this will only work if you render your form as_table