django-selectable / docs / advanced.rst

Advanced Usage

We've gone through the most command and simple use cases for django-selectable. Now we'll take a lot at some of the more advanced features of this project. This assumes that you are comfortable reading and writing a little bit of Javascript making use of jQuery.

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'})

You can also pass the query parameters into the widget using the query_params keyword argument. It depends on your use case as to whether the parameters are know when the form is defined or when an instance of the form is created.

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>

Note

In v0.7 the scope of prepareQuery was updated so that this refers to the current djselectable plugin instance. Previously this refered to the plugin options instance.

Chained Selection

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.

Detecting Client Side Changes

The previous example detected selection changes on the client side to allow passing parameters to the lookup. Since django-selectable is built on top of the jQuery UI Autocomplete plug-in, the widgets expose the events defined by the plugin.

  • djselectablecreate
  • djselectablesearch
  • djselectableopen
  • djselectablefocus
  • djselectableselect
  • djselectableclose
  • djselectablechange

Note

Prior to v0.7 these event names were under the autocomplete namespace. If you are upgrading from a previous version and had customizations using these events you should be sure to update the names.

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.

The multiple select widgets include additional events which indicate when a new item is added or removed from the current list. These events are djselectableadd and djselectableremove. These events pass a dictionary of data with the following keys

  • element: The original text input
  • input: The hidden input to be added for the new item
  • wrapper: The <li> element to be added to the deck
  • deck: The outer <ul> deck element

You can use these events to prevent items from being added or removed from the deck by returning false in the handling function. A simple example is given below:

<script type="text/javascript">
    $(document).ready(function() {
        $(':input[name=my_field_0]').bind('djselectableadd', function(event, item) {
            // Don't allow foo to be added
            if ($(item.input).val() === 'foo') {
                return false;
            }
        });
    });
</script>

Submit On Selection

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 djselectableselect event. This event is fired by the text input which has an index of 0. If your 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('djselectableselect', function(event, ui) {
            $(this).parents("form").submit();
        });
    });
</script>

Dynamically Added Forms

django-selectable can work with dynamically added forms such as inlines in the admin. To make django-selectable work in the admin there is nothing more to do than include the necessary static media as described in the :ref:`Admin Integration <admin-jquery-include>` section.

If you are making use of the popular django-dynamic-formset then you can make django-selectable work by passing bindSelectables to the added option:

<script type="text/javascript">
    $(document).ready(function() {
        $('#my-formset').formset({
                added: bindSelectables
        });
    });
</script>

Currently you must include the django-selectable javascript below this formset initialization code for this to work. See django-selectable issue #31 for some additional detail on this problem.

Label Formats on the Client Side

The lookup label is the text which is shown in the list before it is selected. You can use the :ref:`get_item_label <lookup-get-item-label>` method in your lookup to do this on the server side. This works for most applications. However if you don't want to write your HTML in Python or need to adapt the format on the client side you can use the :ref:`formatLabel <javascript-formatLabel>` option.

formatLabel takes two paramaters the current label and the current selected item. The item is a dictionary object matching what is returned by the lookup's :ref:`format_item <lookup-format-item>`. formatLabel should return the string which should be used for the label.

Note

In v0.7 the scope of formatLabel was updated so that this refers to the current djselectable plugin instance. Previously this refered to the plugin options instance.

Going back to the CityLookup we can adjust the label to wrap the city and state portions with their own classes for additional styling:

<script type="text/javascript">
    $(document).ready(function() {
        function formatLabel(label, item) {
            var data = label.split(',');
            return '<span class="city">' + data[0] + '</span>, <span class="state">' + data[1] + '</span>';
        }
        $('#id_city_0').djselectable('option', 'formatLabel', formatLabel);
    });
</script>

This is a rather simple example but you could also pass additional information in format_item such as a flag of whether the city is the capital and render the state captials differently.

Using with Twitter Bootstrap

django-selectable can work along side with Twitter Bootstrap but there are a few things to take into consideration. Both jQuery UI and Bootstrap define a $.button plugin. This plugin is used by default by django-selectable and expects the UI version. If the jQuery UI JS is included after the Bootstrap JS then this will work just fine but the Bootstrap button JS will not be available. This is the strategy taken by the jQuery UI Bootstrap theme.

Another option is to rename the Bootstrap plugin using the noConflict option.

<!-- Include Bootstrap JS -->
<script>$.fn.bootstrapBtn = $.fn.button.noConflict();</script>
<!-- Include jQuery UI JS -->

Even with this some might complain that it's too resource heavy to include all of jQuery UI when you just want the autocomplete to work with django-selectable. For this you can use the Download Builder to build a minimal set of jQuery UI widgets. django-selectable requires the UI core, autocomplete, menu and button widgets. None of the effects or interactions are needed. Minified this totals around 100 kb of JS, CSS and images (based on jQuery UI 1.10).

Note

For a comparison this is smaller than the minified Bootstrap 2.3.0 CSS which is 105 kb not including the responsive CSS or the icon graphics.

It is possible to remove the dependency on the UI button plugin and instead use the Bootstrap button styles. This is done by overriding the _comboButtonTemplate and _removeButtonTemplate functions used to create the buttons. An example is given below.

<script>
    $.ui.djselectable.prototype._comboButtonTemplate = function (input) {
        var icon = $("<i>").addClass("icon-chevron-down");
        // Remove current classes on the text input
        $(input).attr("class", "");
        // Wrap with input-append
        $(input).wrap('<div class="input-append" />');
        // Return button link with the chosen icon
        return $("<a>").append(icon).addClass("btn btn-small");
    };
    $.ui.djselectable.prototype._removeButtonTemplate = function (item) {
        var icon = $("<i>").addClass("icon-remove-sign");
        // Return button link with the chosen icon
        return $("<a>").append(icon).addClass("btn btn-small pull-right");
    };
</script>
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