DjVue

Handle Django forms with Vue.js and Django REST Framework

This project aims to help to build hybrid views that handle both templates renders as well as the REST API. Useful when the client doesn't have a SPA for the frontend but does need mobile apps or an API or developing an API in an existing project that is required. I suggest checking the example app for seeing a concrete implementation.

The trade-off made is getting rid of Django Forms and replace them with Django REST Framework form renderer.

Requirements

• Django (2.2+)
• DRF

For the form validation and submission:

• Vue.js 2.6
• VeeValidate

Installation

Install djvue (or download from PyPI):

pip install djvue

Add djvue to INSTALLED_APPS in settings.py:

INSTALLED_APPS = (
    # other apps
    "djvue",
)

Enable session authentication for DRF.

Warning

Failing in doing this will make all your views csrf exempted.

REST_FRAMEWORK = {
    # ...
    'DEFAULT_AUTHENTICATION_CLASSES': (
        'rest_framework.authentication.SessionAuthentication',
        # ...
    ),
    # ...
}

If there are files to be uploaded via forms, it's required to include djvue.urls in your root urls.py:

# For Django >= 2.2
urlpatterns += [
    path('', include('djvue.urls'))
]

How it works

Rendering a simple form

DjVue allows you to easily render straightforward forms.

Define the serializer.

class LoginSerializer(serializers.Serializer):
    email = serializers.EmailField(required=True)
    password = serializers.CharField(write_only=True, style={"input_type": "password"})

Your views will require to return the serializer definition and the rendered template on the GET requests, exactly like Django CBVs are doing.

from rest_framework.generics import CreateAPIView
from rest_framework.renderers import TemplateHTMLRenderer, JSONRenderer
from rest_framework.response import Response

from .serializers import LoginSerializer


class LoginView(CreateAPIView):
    renderer_classes = [TemplateHTMLRenderer, JSONRenderer]
    serializer_class = LoginSerializer
    template_name = "login.html"

    def get(self, request, *args, **kwargs):
        return Response({"serializer": self.get_serializer()})

Include the prerequisites at the bottom of base.html

{% load vue_tags %}
.... other scripts
{% vue_starter %}

Vue app

Each form is another Vue instance.

<div id="login-app" hidden>
    ...
</div>

Note

Hide the div holding the Vue.js app to avoid showing to the user un-rendered HTML using the hidden HTML attribute. It can be removed once the DOM has loaded, placed usually at the end of the script.

Form definition

validation-observer

Define the form using VeeValidates's ValidationObserver component.

render_vue_form

Render the serializer as an HTML form using render_vue_form. This template tag is a wrapper around the original DRF render_form template tag which changes the field style.

<validation-observer ref="form" v-slot="{ handleSubmit }" mode="lazy">
    <form @submit.prevent="handleSubmit(submit)" novalidate="true">
        <div class="row">
            <div class="col-sm">
                {% render_vue_form serializer %}
            </div>
        </div>
        <button class="btn btn-primary">Login</button>
    </form>
</validation-observer>

render_vue_field

For a more granular control render_vue_field template tag can be used.

<validation-observer ref="form" v-slot="{ handleSubmit }" mode="lazy">
    <form @submit.prevent="handleSubmit(submit)" novalidate="true">
        <div class="row">
            <div class="col-sm">
                {% render_vue_field serializer.username %}
                {% render_vue_field serializer.password %}
            </div>
        </div>
        <button class="btn btn-primary">Login</button>
    </form>
</validation-observer>

djVueMixin

• Create a new Vue app and use djVueMixin which handles the form validation, file upload, and submission.
• Define the form fields inside data method form object. Note that you need to define manually every form field that has to be passed to the server, excepting file fields, which will cover in another example later.

• Mandatory implementation input

  • actionURL: defines where the form has to be sent via a POST request to the server.
  • success: method is called when the server returns a success response (status 200).

new Vue({
    el: '#login-app',
    mixins: [djVueMixin],
    data() {
        return {
            actionURL: '{% url "login" %}',
            form: {
                email: null,
                password: null
            }
        }
    },
    methods: {
        success(response) {
            window.location.href = "{% url 'user:dashboard' %}"
        }
    }

})
// remove hidden
let appEl = document.getElementById('login-app');
appEl.removeAttribute("hidden");

Display the validation errors

• At this step, live validation is setup. Each form field is validated individually in the partial HTML field. It can be customized by creating a new template pack. Add a placeholder anywhere on the page for rendering forms global validation error like Server Error or better use a toastr or SnackBar.
• Displaying server side field errors is implemented only for one nesting level, if you need more you should override error method from djVueMixin.

<p v-for="error in nonFieldErrors" :key="error" class="text-danger">{( error )}</p>

Advanced usage

from djvue.fields import FileField

class WorkSerializer(serializers.Serializer):
    CHOICES = (
        ("cc", "Chocolate Tested"),
        ("dreamer", "Dreamer"),
        ("sp", "Smokes packing"),
    )
    job = serializers.ChoiceField(choices=CHOICES)
    position = serializers.CharField(required=False)


class ProfileSerializer(serializers.ModelSerializer):
    username = serializers.CharField(max_length=25, min_length=3, required=True,)
    email = serializers.EmailField(required=True)
    password1 = serializers.CharField(
        write_only=True,
        style={"input_type": "password", "rules": "password:@password2"},
    )
    password2 = serializers.CharField(write_only=True, style={"input_type": "password"})
    file = FileField(required=True)
    working_place = WorkSerializer(write_only=True)

    class Meta:
        model = Profile
        fields = (
            "username",
            "email",
            "password1",
            "password2",
            "file",
            "working_place",
        )

File upload

• File upload starts as soon as onchange DOM event occurs. Behind the scene, a global view is uploading the file to a temporary location and returns to the client the path and the original filename which will be sent together with the form data upon submission. If you want to enforce special validation, DjVue batteries can be subclasses to create your custom logic.
• To enable file upload, it's required to use DjVue's FileField instead of the default one.

FileField

A hybrid file field. Renders an input type, accepts as input a dictionary containing the filename and the file path and it serializes the representation like a native serializer.FileField.

serializers.py

from django.core.validators import FileExtensionValidator

from djvue.serializers import FileUploadSerializer


class PDFUploadSerializer(FileUploadSerializer):
    """
    Allows only PDF files to be uploaded
    """
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.fields["file"].validators.append(FileExtensionValidator(allowed_extensions=['pdf']))

views.py

from djvue.views import FileUploadView

class PDFUploadView(FileUploadView):
    serializer_class = PDFUploadSerializer

urls.py

urlpatterns = [
    path('<scrambled-url>', PDFUploadView.as_view(), name="pdf_upload")
   ]

Once the backend is implemented, the Vue.js app is left to be updated and that's all.

new Vue({
    // ...
    uploadURL: "{% url 'pdf_upload' %}"
    // ...
})

Upon form submission, the uploaded files must be linked with some model or pushed somewhere else. Let's see a trivial example of how that can be done, filename and path are always returned by the view using FileUploadSerializer and djVueMixin does the job of POSTing them to the actionURL together with the rest of the form fields.

The current example considers one url for all files which belong to the same form, for handling different validations per file, each field can have it's own upload url by defining upload_url in field style.

any_file = FileField()  # uses the uploadURL defined in the Vue instance
pdf = FileField(style={"upload_url": reverse_lazy("pdf_upload")})
image = FileField(style={"upload_url": reverse_lazy("image_upload")})

serializers.py

class ProfileSerializer(serializers.ModelSerializer):
    def create(self, validated_data):
        user_file = validated_data.pop("file", None)
        profile = Profile.objects.create(**validated_data)
        # # fetch the file from temporary dir
        if user_file is not None and all(
            [user_file.get("path", False), user_file.get("filename", False)]
        ):
            with open(user_file["path"], "rb") as f:
                profile.file.save(user_file["filename"], f)
        return profile

ListFileField

Implements multiple upload, a list of FileField, inheriting all its features. Once a file has been uploaded, the filename will be rendered under it.

multiple_file = ListFileField()  # uses the uploadURL defined in the Vue instance
multiple_pdf = ListFileField(style={"upload_url": reverse_lazy("example:pdf_upload")})

serializers.py

from django.core.files.base import ContentFile

class ProfileSerializer(serializers.ModelSerializer):
    def create(self, validated_data):
        # ...
        multiple_file = validated_data.pop("multiple_file", None)
        profile = Profile(**validated_data)
        profile.save()
        # fetch the file from temporary dir
        if multiple_file is not None and all(
            [a_file.get("path", False) and a_file.get("filename", False) for a_file in multiple_file]
        ):
            for a_file in multiple_file:
                with open(a_file["path"], "rb") as f:
                    ProfileAttachment.objects.create(profile=profile, file=ContentFile(f.read(), a_file["filename"]))

Fieldsets

By default, DjVue can handle also nested serializers with one nesting level, though if you need more, this behavior can be easily changed. Child serializer fields will be rendered in the same format that parent fields are. The only adjustment required to support them is to modify the form key from the data method to include an object which defines the child serializer fields rather than a key-value pair.

new Vue({
    // ...
    data() {
        return {
            form: {
                // ...
                working_place: {
                    job: null,
                    position: null
                }
            }
        }
},

    // ...
})

Formsets

At this moment formset are indeed supported, but they have to be written by hand. It's on the road map to provide utilities for them also. Here's a naive implementation of how they can be done:

serializers.py

class AddressSerializer(serializers.Serializer):
    COUNTRY_CHOICES = (("ro", "Romania"), ("de", "Germany"), ("kw", "Kuwait"))
    country = serializers.ChoiceField(choices=COUNTRY_CHOICES)
    zip_code = serializers.CharField()
    address = serializers.CharField(required=False)

    class Meta:
        list_serializer_class = serializers.ListSerializer


class ProfileSerializer(serializers.ModelSerializer):
    # ...
    addresses = AddressSerializer(many=True)

script.js

let addressIndex = 0

new Vue({
    // ..
    data() {
        return {
            formsetReady: false,
            formsetDefinition: {},
            form: {
                // ..
                addresses: [
                    {
                        id: `address-${addressIndex}`,
                        country: null,
                        zip_code: null,
                        address: null
                    }
                ]
            },
        }
    },
    watch: {
        options() {
            // set the formset definitions
            this.formsetDefinition = this.options.addresses.child.children
            this.formsetReady = true
        }
    },
    methods: {
        addAddress() {
            addressIndex++
            this.form.addresses.push({
                id: `address-${addressIndex}`,
                country: null,
                zip_code: null,
                address: null,
            })
        },
        deleteAddress(index) {
            this.form.addresses.splice(index, 1)
        },

    }
})

Place the formset anywhere inside the form definition wrapped with its own validation-observer.

index.html

<validation-observer ref="addresses">
    <div class="card mb-3" v-for="(address, index) in form.addresses" :key="address.id">
        <div class="card-body">
            <span class="float-right" style="cursor: pointer"
                  @click="deleteAddress(index)">x</span>
            <h4 class="card-title">Address</h4>
            <div class="address-form">

                <validation-provider :name="`country-${index}`" rules="required"
                                     v-slot="{ errors, valid, invalid, validated }" tag="div"
                                     class="form-group">
                    <select v-model="address.country"
                            class="form-control"
                            name="country"
                            :class="{'is-invalid': validated && invalid, 'is-valid': valid}"
                    >
                        <option disabled value="">Select country</option>

                        <option v-for="opt in formsetDefinition.country.choices"
                                :value="opt.value">
                            {( opt.display_name )}
                        </option>

                    </select>
                    <p v-for="error in errors" :key="error" class="text-danger">{( error )}</p>
                </validation-provider>

                <validation-provider :name="`zip_code-${index}`" rules="required"
                                     v-slot="{ errors, valid, invalid, validated }" tag="div"
                                     class="form-group">
                    <input v-model="address.zip_code"
                           type="text"
                           class="form-control mb-2"
                           :class="{'is-invalid': validated && invalid, 'is-valid': valid}"
                           placeholder="Zip Code">
                    <p v-for="error in errors" :key="error" class="text-danger">{( error )}</p>
                </validation-provider>

                <validation-provider :name="`address-${index}`" rules="required"
                                     v-slot="{ errors, valid, invalid, validated }" tag="div"
                                     class="form-group">
                    <textarea v-model="address.address"
                              type="text"
                              class="form-control mb-2"
                              :class="{'is-invalid': validated && invalid, 'is-valid': valid}"
                              placeholder="Address"></textarea>
                    <p v-for="error in errors" :key="error" class="text-danger">{( error )}</p>
                </validation-provider>

            </div>
        </div>
    </div>
</validation-observer>

i18n and custom field error messages

By default, error messages are rendered in the English language. In order to change them, add in settings.py the path of the file where new messages are located.

settings.py

LANGUAGE_CODE = "en-us"

DJVUE_VV_LOCALE_PATH = "example.locale.djvue_messages"

This file must contain a dictionary that matches the language codes defined in LANGUAGES or if your project is not multilingual and if you need to override the default messages, define a dictionary with one key which is matching LANGUAGE_CODE value. The children key which holds the messages must match the VeeValidate keys.

djvue_messages.py

vv_locale = {
    "en-us": {
        "en": {
            "messages": {
                "alpha": "This field may only contain alphabetic characters.",
            }
        }
    },
}

TODOs

• Generate form object from the serializer definition.
• Provide utilities for dynamic formsets.
• Handle unlimited levels of nested serializers?

Credits

Tools used in rendering this package:

• Cookiecutter
• cookiecutter-djangopackage