Source

django-selectable / docs / parameters.rst

Additional Parameters

The basic lookup is based on handling a search based on a single term string. If additional filtering is needed it can be inside the lookup get_query but you would need to define this when the lookup is defined. While this fits a fair number of use cases there are times when you need to define additional query parameters that won't be know until the either the form is bound or until selections are made on the client side. This section will detail how to handle both of these cases.

How Parameters are Passed

As with the search term the additional parameters you define will be passed in request.GET. Since get_query gets the current request so you will have access to them. Since they can be manipulated on the client side, these parameters should be treated like all user input. It should be properly validated and sanitized.

Limiting the Result Set

The number of results are globally limited/paginated by the :ref:`SELECTABLE_MAX_LIMIT` but you can also lower this limit on the field or widget level. Each field and widget takes a limit argument in the __init__ that will be passed back to the lookup through the limit query parameter. The result set will be automatically paginated for you if you use either this parameter or the global setting.

Adding Parameters on the Server Side

Each of the widgets define update_query_parameters which takes a dictionary. The most common way to use this would be in the form __init__.

class FruitForm(forms.Form):
    autocomplete = forms.CharField(
        label='Type the name of a fruit (AutoCompleteWidget)',
        widget=selectable.AutoCompleteWidget(FruitLookup),
        required=False,
    )

    def __init__(self, *args, **kwargs):
        super(FruitForm, self).__init__(*args, **kwargs)
        self.fields['autocomplete'].widget.update_query_parameters({'foo': 'bar'})

Adding Parameters on the Client Side

There are times where you want to filter the result set based other selections by the user such as a filtering cities by a previously selected state. In this case you will need to bind a prepareQuery to the field. This function should accept the query dictionary. You are free to make adjustments to the query dictionary as needed.

<script type="text/javascript">
    function newParameters(query) {
        query.foo = 'bar';
    }

    $(document).ready(function() {
        $('#id_autocomplete').djselectable('option', 'prepareQuery', newParameters);
    });
</script>

Detecting Client Side Changes

Since django-selectable is built on top of the jQuery UI Autocomplete plug-in, the widgets expose the events defined by the plugin.

  • autocompletecreate
  • autocompletesearch
  • autocompleteopen
  • autocompletefocus
  • autocompleteselect
  • autocompleteclose
  • autocompletechange

For the most part these event names should be self-explanatory. If you need additional detail you should refer to the jQuery UI docs on these events.

Chained Selection Example

It's a fairly common pattern to have two or more inputs depend one another such City/State/Zip. In fact there are other Django apps dedicated to this purpose such as django-smart-selects or django-ajax-filtered-fields. It's possible to handle this kind of selection with django-selectable if you are willing to write a little javascript.

Suppose we have city model

and a simple form

We want our users to select a city and if they choose a state then we will only show them cities in that state. To do this we will pass back chosen state as addition parameter with the following javascript:

Then in our lookup we will grab the state value and filter our results on it:

And that's it! We now have a working chained selection example. The full source is included in the example project.

Submit On Selection Example

You might want to help your users by submitting the form once they have selected a valid item. To do this you simply need to listen for the autocompleteselect event. This event is fired by the text input which has an index of 0. If you field is named my_field then input to watch would be my_field_0 such as:

<script type="text/javascript">
    $(document).ready(function() {
        $(':input[name=my_field_0]').bind('autocompleteselect', function(event, ui) {
            $(this).parents("form").submit();
        });
    });
</script>