Advanced search language for Django
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Latest commit e78c354 Apr 28, 2017 @stebunovd stebunovd bump version to 0.8.2

README.rst

DjangoQL

https://travis-ci.org/ivelum/djangoql.svg?branch=master

Advanced search language for Django, with auto-completion. Supports logical operators, parenthesis, table joins, works with any Django models. Tested vs. Python 2.7, 3.5 and 3.6, Django 1.8 - 1.11. Auto-completion feature tested in Chrome, Firefox, Safari, IE9+.

See a video: DjangoQL demo

https://raw.githubusercontent.com/ivelum/djangoql/master/djangoql/static/djangoql/img/completion_example_scaled.png

Contents

Installation

$ pip install djangoql

Add 'djangoql' to INSTALLED_APPS in your settings.py:

INSTALLED_APPS = [
    ...
    'djangoql',
    ...
]

Add it to your Django admin

Add DjangoQLSearchMixin to your model admin, and it will replace standard Django search functionality with DjangoQL search. Example:

from django.contrib import admin

from djangoql.admin import DjangoQLSearchMixin

from .models import Book


@admin.register(Book)
class BookAdmin(DjangoQLSearchMixin, admin.ModelAdmin):
    pass

Language reference

DjangoQL is shipped with comprehensive Syntax Help, which is available in Django admin (see Syntax Help link in auto-completion popup). Here's a quick summary:

DjangoQL looks close to Python syntax, however there're some minor differences. Basically you just reference model fields like you do it in Python code, apply comparison and logical operators and parenthesis. DjangoQL is case-sensitive.

  • model fields: exactly as they are defined in Python code. Access nested properties via ., for example author.last_name;
  • strings must be double-quoted. Single quotes are not supported. To escape a double quote use \";
  • boolean and null values: True, False, None. Please note that they can be combined with equality operators only, so you can write published = False or date_published = None, but published > False will cause an error;
  • logical operators: and, or;
  • comparison operators: =, !=, <, <=, >, >= - work as you expect. ~ and !~ - test that a string contains or not contains a substring (translated into __icontains);
  • test a value vs. list: in, not in. Example: pk in (2, 3).

DjangoQL Schema

Schema defines limitations - what you can do with a DjangoQL query. If you don't specify any schema, DjangoQL will provide a default schema for you. It would recursively walk though all model fields and relations and include everything it could find in the schema, so users would be able to search through everything. However sometimes this is not what you want, either due to DB performance or security concerns. If you'd like to limit search models or fields, you should define a schema. Here's an example:

class UserQLSchema(DjangoQLSchema):
    exclude = (Book,)
    suggest_options = {
        Group: ['name'],
    }

    def get_fields(self, model):
        if model == Group:
            return ['name']
        return super(UserQLSchema, self).get_fields(model)


@admin.register(User)
class CustomUserAdmin(DjangoQLSearchMixin, UserAdmin):
    djangoql_schema = UserQLSchema

In the example above we created a schema that does 3 things:

  • excludes Book model from search via exclude option. Instead of exclude you may also use include, it would limit search to listed models only;
  • limits available search fields for Group model to name field only, in .get_fields() method;
  • enables completion options for Group names via suggest_options.

Important note about suggest_options: it synchronously pulls all values for given models and fields, so you should avoid large querysets there. If you'd like to define custom suggestion options, see below.

Custom search fields

Sometimes you may want deeper customization, and here custom search fields come into play. You may use them to search by annotations, or to define custom suggestion options, or define fully custom search logic. DjangoQL defines the following base field classes in djangoql.schema that you may subclass to define your own behavior:

  • IntField
  • FloatField
  • StrField
  • BoolField
  • DateField
  • DateTimeField
  • RelationField

Here are examples for common use cases:

Search by queryset annotations:

from djangoql.schema import DjangoQLSchema, IntField


class UserQLSchema(DjangoQLSchema):
    def get_fields(self, model):
        fields = super(UserQLSchema, self).get_fields(model)
        if model == User:
            fields = [IntField(name='groups_count')] + fields
        return fields


@admin.register(User)
class CustomUserAdmin(DjangoQLSearchMixin, UserAdmin):
    djangoql_schema = UserQLSchema

    def get_queryset(self, request):
        qs = super(CustomUserAdmin, self).get_queryset(request)
        return qs.annotate(groups_count=Count('groups'))

Let's take a closer look what's happening in the example above. First, we add groups_count annotation to queryset that is used by Django admin in CustomUserAdmin.get_queryset() method. It would contain no. of groups user belongs to. As our queryset now pulls this column, we can now filter by it, we just need to include it into the schema. In UserQLSchema.get_fields() we define a custom integer search field for User model. It's name should match the name of the column in our queryset.

Custom suggestion options

from djangoql.schema import DjangoQLSchema, StrField


class GroupNameField(StrField):
    model = Group
    name = 'name'
    suggest_options = True

    def get_options(self):
        return super(GroupNameField, self).get_options().\
            annotate(users_count=Count('user')).\
            order_by('-users_count')


class UserQLSchema(DjangoQLSchema):
    def get_fields(self, model):
        if model == Group:
            return ['id', GroupNameField()]
        return super(UserQLSchema, self).get_fields(model)


@admin.register(User)
class CustomUserAdmin(DjangoQLSearchMixin, UserAdmin):
    djangoql_schema = UserQLSchema

In this example we've defined a custom GroupNameField that sorts suggestions for group names by popularity (no. of users in a group) instead of default alphabetical sorting.

Custom search lookup

DjangoQL base fields provide two basic methods that you can override to substitute either search column, or search value, or both - .get_lookup_name() and .get_lookup_value(value):

class UserDateJoinedYear(IntField):
    name = 'date_joined_year'

    def get_lookup_name(self):
        return 'date_joined__year'


class UserQLSchema(DjangoQLSchema):
    def get_fields(self, model):
        fields = super(UserQLSchema, self).get_fields(model)
        if model == User:
            fields = [UserDateJoinedYear()] + fields
        return fields


@admin.register(User)
class CustomUserAdmin(DjangoQLSearchMixin, UserAdmin):
    djangoql_schema = UserQLSchema

In this example we've defined custom date_joined_year search field for users, and used built-in Django __year filter option in .get_lookup_name() to filter by date year only. Similarly you can use .get_lookup_value(value) hook to modify search value before it's used in the filter.

Fully custom search lookup

.get_lookup_name() and .get_lookup_value(value) hooks can cover many simple use cases, but sometimes they're not enough and you want fully custom search logic. In such cases you can override main .get_lookup() method of a field. Example below demonstrates User age search:

from djangoql.schema import DjangoQLSchema, IntField


class UserAgeField(IntField):
    """
    Search by given number of full years
    """
    model = User
    name = 'age'

    def get_lookup_name(self):
        """
        We'll be doing comparisons vs. this model field
        """
        return 'date_joined'

    def get_lookup(self, path, operator, value):
        """
        The lookup should support with all operators compatible with IntField
        """
        if operator == 'in':
            result = None
            for year in value:
                condition = self.get_lookup(path, '=', year)
                result = condition if result is None else result | condition
            return result
        elif operator == 'not in':
            result = None
            for year in value:
                condition = self.get_lookup(path, '!=', year)
                result = condition if result is None else result & condition
            return result

        value = self.get_lookup_value(value)
        search_field = '__'.join(path + [self.get_lookup_name()])
        year_start = self.years_ago(value + 1)
        year_end = self.years_ago(value)
        if operator == '=':
            return (
                Q(**{'%s__gt' % search_field: year_start}) &
                Q(**{'%s__lte' % search_field: year_end})
            )
        elif operator == '!=':
            return (
                Q(**{'%s__lte' % search_field: year_start}) |
                Q(**{'%s__gt' % search_field: year_end})
            )
        elif operator == '>':
            return Q(**{'%s__lt' % search_field: year_start})
        elif operator == '>=':
            return Q(**{'%s__lt' % search_field: year_end})
        elif operator == '<':
            return Q(**{'%s__gt' % search_field: year_end})
        elif operator == '<=':
            return Q(**{'%s__gte' % search_field: year_start})

    def years_ago(self, n):
        timestamp = now()
        try:
            return timestamp.replace(year=timestamp.year - n)
        except ValueError:
            # February 29
            return timestamp.replace(month=2, day=28, year=timestamp.year - n)


class UserQLSchema(DjangoQLSchema):
    def get_fields(self, model):
        fields = super(UserQLSchema, self).get_fields(model)
        if model == User:
            fields = [UserAgeField()] + fields
        return fields


@admin.register(User)
class CustomUserAdmin(DjangoQLSearchMixin, UserAdmin):
    djangoql_schema = UserQLSchema

Can I use it outside of Django admin?

Sure. You can add DjangoQL search functionality to any Django model using DjangoQLQuerySet:

from django.db import models

from djangoql.queryset import DjangoQLQuerySet


class Book(models.Model):
    name = models.CharField(max_length=255)
    author = models.ForeignKey('auth.User')

    objects = DjangoQLQuerySet.as_manager()

With the example above you can perform search like this:

qs = Book.objects.djangoql(
    'name ~ "war" and author.last_name = "Tolstoy"'
)

It returns a normal queryset, so you can extend it and reuse if necessary. The following code works fine:

print(qs.count())

Alternatively you can add DjangoQL search to any existing queryset, even if it's not an instance of DjangoQLQuerySet:

from django.contrib.auth.models import User

from djangoql.queryset import apply_search

qs = User.objects.all()
qs = apply_search(qs, 'groups = None')
print(qs.exists())

Schemas can be specified either as a queryset option, or passed to .djangoql() queryset method directly:

class BookQuerySet(DjangoQLQuerySet):
    djangoql_schema = BookSchema


class Book(models.Model):
    ...

    objects = BookQuerySet.as_manager()

# Now, Book.objects.djangoql() will use BookSchema by default:
Book.objects.djangoql('name ~ "Peace")  # uses BookSchema

# Overriding default queryset schema with AnotherSchema:
Book.objects.djangoql('name ~ "Peace", schema=AnotherSchema)

You can also provide schema as an option for apply_search()

qs = User.objects.all()
qs = apply_search(qs, 'groups = None', schema=CustomSchema)

Using completion widget outside of Django admin

Completion widget is not tightly coupled to Django admin, so you can easily use it outside of admin if you want. Here is an example:

Template code, completion_demo.html:

{% load static %}
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>DjangoQL completion demo</title>
  <link rel="stylesheet" type="text/css" href="{% static 'djangoql/css/completion.css' %}" />
  <script src="{% static 'djangoql/js/lib/lexer.js' %}"></script>
  <script src="{% static 'djangoql/js/completion.js' %}"></script>
</head>
<body>

  <form action="" method="get">
    <p style="color: red">{{ error }}</p>
    <textarea name="q" cols="40" rows="1" autofocus>{{ q }}</textarea>
  </form>

  <ul>
  {% for item in search_results %}
    <li>{{ item }}</li>
  {% endfor %}
  </ul>

  <script>
    DjangoQL.DOMReady(function () {
      DjangoQL.init({
        // either JS object with a result of DjangoQLSchema(MyModel).as_dict(),
        // or an URL from which this information could be loaded asynchronously
        introspections: {{ introspections|safe }},

        // css selector for query input. It should be a textarea
        selector: 'textarea[name=q]',

        // optional, you can provide URL for Syntax Help link here.
        // If not specified, Syntax Help link will be hidden.
        syntaxHelp: null,

        // optional, enable textarea auto-resize feature. If enabled,
        // textarea will automatically grow its height when entered text
        // doesn't fit, and shrink back when text is removed. The purpose
        // of this is to see full search query without scrolling, could be
        // helpful for really long queries.
        autoResize: true
      });
    });
  </script>
</body>
</html>

And in your views.py:

import json

from django.contrib.auth.models import Group, User
from django.shortcuts import render_to_response
from django.views.decorators.http import require_GET

from djangoql.exceptions import DjangoQLError
from djangoql.queryset import apply_search
from djangoql.schema import DjangoQLSchema


class UserQLSchema(DjangoQLSchema):
    include = (User, Group)


@require_GET
def completion_demo(request):
    q = request.GET.get('q', '')
    error = ''
    query = User.objects.all().order_by('username')
    if q:
        try:
            query = apply_search(query, q, schema=UserQLSchema)
        except DjangoQLError as e:
            query = query.none()
            error = str(e)
    return render_to_response('completion_demo.html', {
        'q': q,
        'error': error,
        'search_results': query,
        'introspections': json.dumps(UserQLSchema(query.model).as_dict()),
    })

License

MIT