djangoql 0.12.6

DjangoQL: Advanced search language for Django

Copyright (c) 2017 ivelum

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Description: DjangoQL
========

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

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 - 3.7, Django 1.8 - 2.2. Auto-completion feature tested
in Chrome, Firefox, Safari, IE9+.

See a video: `DjangoQL demo <https://youtu.be/oKVff4dHZB8>`_

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

Contents
--------

* `Installation`_
* `Add it to your Django admin`_
* `Using together with a standard Django admin search`_
* `Language reference`_
* `DjangoQL Schema`_
* `Custom search fields`_
* `Can I use it outside of Django admin?`_
* `Using completion widget outside of Django admin`_

Installation
------------

.. code:: shell

$ pip install djangoql

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

.. code:: python

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:

.. code:: python

from django.contrib import admin

from djangoql.admin import DjangoQLSearchMixin

from .models import Book


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


Using together with a standard Django admin search
--------------------------------------------------

If you define ``search_fields`` on your ModelAdmin class, DjangoQL integration
would automatically recognize this and let users choose between a standard
Django search (that you specified with ``search_fields``) and Advanced Search
with DjangoQL. Example:

.. code:: python

@admin.register(Book)
class BookAdmin(DjangoQLSearchMixin, admin.ModelAdmin):
search_fields = ('title', 'author__name')

For the example above, a checkbox that controls search mode would appear near
the search input. If you don't want two search modes, simply remove
``search_fields`` from your ModelAdmin class.


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:

.. code:: python

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 looks for ``choices`` model field
parameter first, and if it's not specified - it synchronously pulls all values
for given model 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:**

.. code:: python

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**

.. code:: python

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)``:

.. code:: python

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:

.. code:: python

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__lte' % 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``:

.. code:: python

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:

.. code:: python

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:

.. code:: python

print(qs.count())

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

.. code:: python

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:

.. code:: python

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()``

.. code:: python

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``:

.. code:: 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 () {
new DjangoQL({
// 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 or HTMLElement object.
// 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``:

.. code:: python

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

Platform: UNKNOWN
Classifier: Development Status :: 4 - Beta
Classifier: Intended Audience :: Developers
Classifier: Natural Language :: English
Classifier: License :: OSI Approved :: MIT License
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3.5
Classifier: Programming Language :: Python :: 3.6