Tutorial#

Note

For demo links to work, you need to run the test project on localhost.

Overview#

Autocompletes are based on 3 moving parts:

  • widget compatible with the model field, does the initial rendering,

  • javascript widget initialization code, to trigger the autocomplete,

  • and a view used by the widget script to get results from.

Create an autocomplete view#

The only purpose of the autocomplete view is to serve relevant suggestions for the widget to propose to the user. DAL leverages Django’s class based views and Mixins to for code reuse.

Note

Do not miss the Classy Class-Based Views website which helps a lot to work with class-based views in general.

In this tutorial, we’ll first learn to make autocompletes backed by a QuerySet. Suppose we have a Country Model which we want to provide a Select2 autocomplete widget for in a form. If a users types an “f” it would propose “Fiji”, “Finland” and “France”, to authenticated users only:

_images/autocomplete.png

The base view for this is Select2QuerySetView.

from dal import autocomplete

from your_countries_app.models import Country


class CountryAutocomplete(autocomplete.Select2QuerySetView):
    def get_queryset(self):
        # Don't forget to filter out results depending on the visitor !
        if not self.request.user.is_authenticated:
            return Country.objects.none()

        qs = Country.objects.all()

        if self.q:
            qs = qs.filter(name__istartswith=self.q)

        return qs

Note

For more complex filtering, refer to official documentation for the QuerySet API.

Register the autocomplete view#

Create a named url for the view, ie:

from your_countries_app.views import CountryAutocomplete

urlpatterns = [
    url(
        r'^country-autocomplete/$',
        CountryAutocomplete.as_view(),
        name='country-autocomplete',
    ),
]

Ensure that the url can be reversed, ie:

./manage.py shell
In [1]: from django.urls import reverse
In [2]: #older django versions: from django.core.urlresolvers import reverse

In [3]: reverse('country-autocomplete')
Out[2]: u'/country-autocomplete/'

Danger

As you might have noticed, we have just exposed data through a public URL. Please don’t forget to do proper permission checks in get_queryset.

Use the view in a Form widget#

Before you begin#

You should be able to open the view at this point:

_images/view.png

We can now use the autocomplete view our Person form, for its birth_country field that’s a ForeignKey. So, we’re going to override the default ModelForm fields, to use a widget to select a Model with Select2, in our case by passing the name of the url we have just registered to ModelSelect2.

Set form widgets#

Setup your autocomplete form widget for this view in the Form.Meta.widgets dict:

from dal import autocomplete

from django import forms


class PersonForm(forms.ModelForm):
    class Meta:
        model = Person
        fields = ('__all__')
        widgets = {
            'birth_country': autocomplete.ModelSelect2(url='country-autocomplete')
        }

If we need the country autocomplete view for a widget used for a ManyToMany relation instead of a ForeignKey, with a model like that:

class Person(models.Model):
    visited_countries = models.ManyToManyField('your_countries_app.country')

Then we would use the ModelSelect2Multiple widget, ie.:

widgets = {
    'visited_countries': autocomplete.ModelSelect2Multiple(url='country-autocomplete')
}

Danger

If you declare a form field instead of just the widget, Django admin won’t add the “add” and “edit” button next to the autocomplete field for single model choice. If you want to both declare your field and have Django admin’s add / remove buttons then you can use the following method with djhacker.

Automation with djhacker#

import djhacker  # don't forget to pip install djhacker
from django import forms
djhacker.formfield(
    Person.birth_country,
    forms.ModelChoiceField,
    widget=autocomplete.ModelSelect2(url='country-autocomplete')
)

The above example demonstrates how to integrate your autocomplete view and form field automatically throughout Django without having to define custom model forms all the time.

Passing options to select2#

Select2 supports a bunch of options. These options may be set in data-* attributes. For example:

# Instanciate a widget with a bunch of options for select2:
autocomplete.ModelSelect2(
    url='select2_fk',
    attrs={
        # Set some placeholder
        'data-placeholder': 'Autocomplete ...',
        # Only trigger autocompletion after 3 characters have been typed
        'data-minimum-input-length': 3,
    },
)

Note

Setting a placeholder will result in generation of an an empty option tag, which select2 requires.

Using autocompletes in the admin#

Note

If using djhacker, you can skip this section: your autocomplete should already be working in the admin.

We can make ModelAdmin to use our form, ie:

from django.contrib import admin

from your_person_app.models import Person
from your_person_app.forms import PersonForm


class PersonAdmin(admin.ModelAdmin):
    form = PersonForm
admin.site.register(Person, PersonAdmin)

Note that this also works with inlines, ie:

class PersonInline(admin.TabularInline):
    model = Person
    form = PersonForm

Using autocompletes outside the admin#

Ensure that jquery is loaded before {{ form.media }}:

{% extends 'base.html' %}
{# Don't forget that one ! #}
{% load static %}

{% block content %}
<div>
    <form action="" method="post">
        {% csrf_token %}
        {{ form.as_p }}

        <table style="display: none">
            {{ view.formset.empty_form }}
        </table>

        <table>
            {{ view.formset }}
        </table>

        <span id="add-form" class="button">Add form</span>

        <input type="submit" />
    </form>
</div>
{% endblock %}

{% block footer %}
<script type="text/javascript" src="{% static 'admin/js/vendor/jquery/jquery.js' %}"></script>

{{ form.media }}

<script>
(function($) {
    $('#add-form').click(function() {
        var index = $('#id_inline_test_models-TOTAL_FORMS').val()
        var newTable = $('#id_inline_test_models-__prefix__-DELETE').parents('table').clone()
        newTable.find(':input').each(function() {
            for (attr of ['name', 'id'])
                $(this).attr(
                    attr,
                    $(this).attr(attr).replace('__prefix__', index)
                )
        })
        newTable.insertBefore($(this))
        $('#id_inline_test_models-TOTAL_FORMS').val(
            parseInt($('#id_inline_test_models-TOTAL_FORMS').val()) + 1
        )
        newTable.slideDown()
    })
})($)
</script>
{% endblock %}

Displaying results using custom HTML#

You can display custom HTML code for results by setting the data-html attribute on your widget and overriding the view get_result_label() method to return HTML code.

from django.utils.html import format_html

class CountryAutocomplete(autocomplete.Select2QuerySetView):
    def get_result_label(self, result):
        return format_html('<img src="flags/{}.png"> {}', result.name, result.name)


class PersonForm(forms.ModelForm):
    class Meta:
        widgets = {
            'birth_country': autocomplete.ModelSelect2(
                url='country-autocomplete',
                attrs={'data-html': True}
            )
        }

Note

Take care to escape anything you put in HTML code to avoid XSS attacks when displaying data that may have been input by a user! format_html helps.

Displaying selected result differently than in list#

You can display selected result in different way than results in list by overriding the view get_selected_result_label() method.

class CountryAutocomplete(autocomplete.Select2QuerySetView):
    def get_result_label(self, item):
        return item.full_name

    def get_selected_result_label(self, item):
        return item.short_name

Setting the data-html attribute affects both selected result and results in list. If you want to enable HTML separately set data-selected-html or data-result-html attribute respectively.

Overriding javascript code#

We need javascript initialization for the widget both when:

  • The page is loaded.

  • A widget is dynamically added, i.e. with formsets.

This is handled by autocomplete_light.js, which is going to trigger an event called dal-init-function on the document when Django Autocomplete Light has initialized. At this point you can simply call yl.registerFunction() to register your custom function.

yl.registerFunction() takes two arguments name and func. The first argument name is the name of name the function. It should be the same as the value of your widget autocomplete_function property which in turn is the value of the data-autocomplete-light-function HTML attribute on your input or select field. The second argument func is the callback function to be run by Django Autocomplete Light when it initializes your input autocomplete.

autocomplete_light.js also keeps track of initialized elements to prevent double-initialization.

Take dal_select2 for example, it is initialized by dal_select2/static/autocomplete_light/select2.js as such:

document.addEventListener('dal-init-function', function () {
    yl.registerFunction( 'select2', function ($, element) {
        // autocomplete function here
    });
})

This example defines an anonymous function as a callback that will be called when Django Autocomplete Light initializes your autocomplete input field. It will also be called when any new field is added, such as a inline formset. The function will be called for any element with an attribute data-autocomplete-light-function value that is the same as the function name.

When Django Autocomplete Light calls your function two arguments are passed in. The first is the django.jQuery object. This is done since your function may not have access to django.jQuery in the lexical environment when the function was placed into memory. This of course causes your function to not have access to jQuery, which may be a problem.

The second argument is the input field DOM element. You can get the jQuery object by simply calling var $element = $(element); inside your function.

So, you can replace the default callback by doing two things:

Example widget:

class YourWidget(ModelSelect2):
    autocomplete_function = 'your_autocomplete_function'

Example script:

document.addEventListener('dal-init-function', function () {
    yl.registerFunction( 'your_autocomplete_function', function ($, element) {
        var $element = $(element);
        // autocomplete function here
    });
})

Listening for the initialization of a specific input#

To know when a specific dal input has been initialized, we can listen for the event dal-element-initialized.

Example opening and setting focus on a dal input after initialization:

$(document).on("dal-element-initialized", function (e) {
    if (e.detail.element.id === "my_dal_element_id") {
        $("#my_dal_element_id").select2("open").trigger("focus");
    }
});

Creation of new choices in the autocomplete form#

The view may provide an extra option when it can’t find any result matching the user input. That option would have the label Create "query", where query is the content of the input and corresponds to what the user typed in. As such:

_images/create_option.png

This allows the user to create objects on the fly from within the AJAX widget. When the user selects that option, the autocomplete script will make a POST request to the view. It should create the object and return the pk, so the item will then be added just as if it already had a PK:

_images/created_option.png

To enable this, first the view must know how to create an object given only self.q, which is the variable containing the user input in the view. Set the create_field view option to enable creation of new objects from within the autocomplete user interface, ie:

urlpatterns = [
    url(
        r'^country-autocomplete/$',
        CountryAutocomplete.as_view(create_field='name', validate_create=True),
        name='country-autocomplete',
    ),
]

This way, the option ‘Create “Tibet”’ will be available if a user inputs “Tibet” for example. When the user clicks it, it will make the post request to the view which will do Country.objects.create(name='Tibet'). It will be included in the server response so that the script can add it to the widget.

By activating valide_create=True, a full_clean will be run on the create_field, thus validating all the validators on the field.

Note that creating objects is allowed to logged-in users with add permission on the resource. If you want to grant add permission to a user, you have to explicitly set it with something like:

permission = Permission.objects.get(name='Can add your-model-name')
user.user_permissions.add(permission)

Note that the above applies for new objects that only require one field. For more complex objects, django-addanother should be considered. With Django Add-Another, a “+” icon is rendered next to the search widget. When clicking this button, an object can be added inside a popup. Once saved, the popup will close and the newly added object will be selected in the widget.

Filtering results based on the value of other fields in the form#

In the live demo, create a TestModel with owner=None, and another with owner=test (test being the user you log in with). Then, in in a new form, you’ll see both options if you leave the owner select empty:

_images/all.png

But if you select test as an owner, and open the autocomplete again, you’ll only see the option with owner=test:

_images/mine.png

Let’s say we want to add a “Continent” choice field in the form, and filter the countries based on the value on this field. We then need the widget to pass the value of the continent field to the view when it fetches data. We can use the forward widget argument to do this:

class PersonForm(forms.ModelForm):
    continent = forms.ChoiceField(choices=CONTINENT_CHOICES)

    class Meta:
        model = Person
        fields = ('__all__')
        widgets = {
            'birth_country': autocomplete.ModelSelect2(url='country-autocomplete',
                                                       forward=['continent'])
        }

DAL’s Select2 configuration script will get the value fo the form field named 'continent' and add it to the autocomplete HTTP query. This will pass the value for the “continent” form field in the AJAX request, and we can then filter as such in the view:

class CountryAutocomplete(autocomplete.Select2QuerySetView):
    def get_queryset(self):
        if not self.request.user.is_authenticated:
            return Country.objects.none()

        qs = Country.objects.all()

        continent = self.forwarded.get('continent', None)

        if continent:
            qs = qs.filter(continent=continent)

        if self.q:
            qs = qs.filter(name__istartswith=self.q)

        return qs

Types of forwarded values#

There are three possible types of value which you can get from self.forwarded field: boolean, string or list of strings. DAL forward JS applies the following rules when figuring out which type to use when you forward particular field:

  • if there is only one field in the form or subform with given name and this field is a checkbox without value HTML-attribute, then a boolean value indicating if this checkbox is checked is forwarded;

  • if there is only one field in the form or subform with given name and it has multiple HTML-attribute, then this field is forwarded as a list of strings, containing values from this field.

  • if there are one or more fields in the form with given name and all of them are checkboxes with HTML-attribute value set, then the list of strings containing checked checkboxes is forwarded.

  • Otherwise field value forwarded as a string.

Renaming forwarded values#

Let’s assume that you have the following form using linked autocomplete fields:

class ShippingForm(forms.Form):
    src_continent = forms.ModelChoiceField(
        queryset=Continent.objects.all(),
        widget=autocomplete.ModelSelect2(url='continent-autocomplete'))
    src_country = forms.ModelChoiceField(
        queryset=Country.objects.all(),
        widget=autocomplete.ModelSelect2(
            url='country-autocomplete',
            forward=('src_continent',)))

And the following autocomplete view for country:

class CountryAutocomplete(autocomplete.Select2QuerySetView):
    def get_queryset(self):
        if not self.request.is_authenticated:
            return Country.objects.none()

        qs = Country.objects.all()

        continent = self.forwarded.get('continent', None)

        if continent:
            qs = qs.filter(continent=continent)

        if self.q:
            qs = qs.filter(name__istartswith=self.q)

        return qs

You cannot use this autocomplete view together with your form because the name forwarded from the form differs from the name that autocomplete view expects.

You can rename forwarded fields using class-based forward declaration to pass src_continent value as continent:

from dal import forward

class ShippingForm(forms.Form):
    src_continent = forms.ModelChoiceField(
        queryset=Continent.objects.all(),
        widget=autocomplete.ModelSelect2(url='continent-autocomplete'))
    src_country = forms.ModelChoiceField(
        queryset=Country.objects.all(),
        widget=autocomplete.ModelSelect2(
            url='country-autocomplete',
            forward=(forward.Field('src_continent', 'continent'),)))

Of course, you can mix up string-based and class-based forwarding declarations:

some_field = forms.ModelChoiceField(
        queryset=SomeModel.objects.all(),
        widget=autocomplete.ModelSelect2(
            url='some-autocomplete',
            forward=(
                'f1',  # String based declaration
                 forward.Field('f2'),  # Works the same way as above declaration
                 forward.Field('f3', 'field3'),  # With rename
                 forward.Const(42, 'f4')  # Constant forwarding (see below)
                 )

Forwarding arbitrary constant values#

The other thing you can do with class-based forwarding declaration is to forward an arbitrary constant without adding extra hidden fields to your form.

from dal import forward

class EuropeanShippingForm(forms.Form):
    src_country = forms.ModelChoiceField(
        queryset=Country.objects.all(),
        widget=autocomplete.ModelSelect2(
            url='country-autocomplete',
            forward=(forward.Const('europe', 'continent'),)))

For src_country field “europe” will always be forwarded as continent value.

Forwarding own selected value#

Quite often (especially in multiselect) you may want to exclude value which is already selected from autocomplete dropdown. Usually it can be done by forwarding a field by name. The forward argument expects a tuple, so don’t forget the trailing comma if the tuple only has one element.

from dal import forward

class SomeForm(forms.Form):
    countries = forms.ModelMultipleChoiceField(
        queryset=Country.objects.all(),
        widget=autocomplete.ModelSelect2Multiple(
            url='country-autocomplete',
            forward=("countries", )

For this special case DAL provides a shortcut named Self().

from dal import forward

class SomeForm(forms.Form):
    countries = forms.ModelMultipleChoiceField(
        queryset=Country.objects.all(),
        widget=autocomplete.ModelSelect2Multiple(
            url='country-autocomplete',
            forward=(forward.Self(),)

In this case the value from countries will be available from autocomplete view as self.forwarded['self']. Of course, you can customize destination name by passing dst parameter to Self constructor.

Customizing forwarding logic#

DAL tries hard to reasonably forward any standard HTML form field. For some non-standard fields DAL logic could be not good enough. For these cases DAL provides a way to customize forwarding logic using JS callbacks. You can register JS forward handler on your page:

// autocompleteElem here is an HTML element for autocomplete field
yl.registerForwardHandler("my_awesome_handler", function (autocompleteElem) {
    return doSomeMagicAndGetValueFromSpace();
});

Then you should add forward declaration to your field as follows:

from dal import forward

class ShippingForm(forms.Form):
    country = forms.ModelChoiceField(
        queryset=Country.objects.all(),
        widget=autocomplete.ModelSelect2(
            url='country-autocomplete',
            forward=(forward.JavaScript('my_awesome_handler', 'magic_number'),)))

In this case the value returned from your registered handler will be forwarded to autocomplete view as magic_number.

Building blocks for custom logic#

Javascript logic for forwarding field values is a bit sophisticated. In order to forward field value DAL searches for the field considering form prefixes and then decides how to forward it to the server (should it be list, string or boolean value). When you implement your own logic for forwarding you may want to reuse this logic from DAL.

For this purpose DAL provides two JS functions:

  • getFieldRelativeTo(element, name) - get field by name relative to this autocomplete field just like DAL does when forwarding a field.

  • getValueFromField(field) - get value to forward from field just like DAL does when forwarding a field.

For the purpose of understanding the logic: you can implement forwarding of some standard field by yourself as follows (you probably should never write this code yourself):

yl.registerForwardHandler("poormans_field_forward",
    function (elem) {
        return yl.getValueFromField(
            yl.getFieldRelativeTo(elem, "some_field"));
    });

Clearing autocomplete on forward field change#

You can use the $.getFormPrefix() jQuery plugin used by DAL to clear the birth_country autocomplete widget from the above example when the continent field changes with such a snippet:

$(document).ready(function() {
    // Bind on continent field change
    $(':input[name$=continent]').on('change', function() {
        // Get the field prefix, ie. if this comes from a formset form
        var prefix = $(this).getFormPrefix();

        // Clear the autocomplete with the same prefix
        $(':input[name=' + prefix + 'birth_country]').val(null).trigger('change');
    });
});

To autoload the script with the form, you can use Form.Media.

Autocompleting based on a List of Strings#

Sometimes it is useful to specify autocomplete choices based on a list of strings rather than a QuerySet. This can be achieved with the Select2ListView class:

class CountryAutocompleteFromList(autocomplete.Select2ListView):
    def get_list(self):
        return ['France', 'Fiji', 'Finland', 'Switzerland']

This class can then be registered as in the previous example. Suppose we register it under URL ‘country-list-autocomplete’. We can then a create a ListSelect2 widget with:

widget = autocomplete.ListSelect2(url='country-list-autocomplete')

With this in place, if a user types the letter f’ in the widget, choices ‘France’, ‘Fiji’, and ‘Finland’ would be offered. Like the Select2QuerySetView, the Select2ListView is case insensitive.

Two fields are provided, Select2ListChoiceField, Select2ListCreateChoiceField that can be used to make it easier to avoid problems when using Select2ListView. For example:

def get_choice_list():
    return ['France', 'Fiji', 'Finland', 'Switzerland']


class CountryForm(forms.ModelForm):
    country = autocomplete.Select2ListChoiceField(
        choice_list=get_choice_list,
        widget=autocomplete.ListSelect2(url='country-list-autocomplete')
    )

By default, the selections in Select2ListView can map directly to a list, resulting in the same text and value for each option.

To define your own values for each selection, provide a list-of-lists or list-of-tuples for the Select2ListView choice_list. For example:

class CountryAutocompleteFromList(autocomplete.Select2ListView):
    def get_list(self):
        return [
            ['France_value', 'France'],
            ['Fiji_value', 'Fiji'],
            ['Finland_value', 'Finland'],
            ['Switzerland_value', 'Switzerland']
        ]


def get_choice_list():
    return [
        ['France_value', 'France'],
        ['Fiji_value', 'Fiji'],
        ['Finland_value', 'Finland'],
        ['Switzerland_value', 'Switzerland']
    ]


class CountryForm(forms.ModelForm):
    country = autocomplete.Select2ListChoiceField(
        choice_list=get_choice_list,
        widget=autocomplete.ListSelect2(url='country-list-autocomplete')
    )

Select2ListCreateChoiceField allows you to provide custom text from a Select2List widget and should be used if you define Select2ListViewAutocomplete.create.

It is better to use the same source for Select2ListViewAutocomplete.get_list in your view and the Select2ListChoiceField choice_list kwarg to avoid unexpected behavior.

An opt-group version is available in a similar fashion by inheriting Select2GroupListView. For example:

class CountryAutocompleteFromList(autocomplete.Select2GroupListView):
    def get_list(self):
        return [
            (None, ['Mars Colony',]),
            ("Country", ['France', 'Fiji', 'Finland', 'Switzerland'])
        ]

As with Select2ListView, for opt-groups with specified values, provide a list-of-lists or list-of-tuples to the Select2GroupListView get_list method. For example:

class CountryAutocompleteFromList(autocomplete.Select2GroupListView):
    def get_list(self):
        return [
            ([None, None], [['Mars_colony_value', 'Mars Colony']]),
            (
                ['Country_value', 'Country'],
                [
                    ['France_value', 'France'],
                    ['Fiji_value', 'Fiji'],
                    ['Finland_value', 'Finland'],
                    ['Switzerland_value', 'Switzerland']
                ]
            )
        ]