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eloquent-0.5
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The Eloquent ORM provides a simple yet beautiful ActiveRecord implementation.
| ویژگی | مقدار |
|---|---|
| سیستم عامل | - |
| نام فایل | eloquent-0.5 |
| نام | eloquent |
| نسخه کتابخانه | 0.5 |
| نگهدارنده | [] |
| ایمیل نگهدارنده | [] |
| نویسنده | Sébastien Eustace |
| ایمیل نویسنده | sebastien.eustace@gmail.com |
| آدرس صفحه اصلی | https://github.com/sdispater/eloquent |
| آدرس اینترنتی | https://pypi.org/project/eloquent/ |
| مجوز | MIT |
Eloquent
########
.. image:: https://travis-ci.org/sdispater/eloquent.png
:alt: Eloquent Build status
:target: https://travis-ci.org/sdispater/eloquent
The Eloquent ORM provides a simple yet beautiful ActiveRecord implementation.
It is inspired by the database part of the `Laravel framework <http://laravel.com>`_,
but largely modified to be more pythonic.
The full documentation is available here: http://eloquent.readthedocs.org
Installation
============
You can install Eloquent in 2 different ways:
* The easier and more straightforward is to use pip
.. code-block:: bash
pip install eloquent
* Install from source using the official repository (https://github.com/sdispater/eloquent)
The different dbapi packages are not part of the package dependencies,
so you must install them in order to connect to corresponding databases:
* Postgres: ``pyscopg2``
* MySQL: ``PyMySQL`` or ``mysqlclient``
* Sqlite: The ``sqlite3`` module is bundled with Python by default
Basic Usage
===========
Configuration
-------------
All you need to get you started is the configuration describing your database connections
and passing it to a ``DatabaseManager`` instance.
.. code-block:: python
from eloquent import DatabaseManager, Model
config = {
'mysql': {
'driver': 'mysql',
'host': 'localhost',
'database': 'database',
'username': 'root',
'password': '',
'prefix': ''
}
}
db = DatabaseManager(config)
Model.set_connection_resolver(db)
Defining a model
----------------
.. code-block:: python
class User(Model):
pass
Note that we did not tell the ORM which table to use for the ``User`` model. The plural "snake case" name of the
class name will be used as the table name unless another name is explicitly specified.
In this case, the ORM will assume the ``User`` model stores records in the ``users`` table.
You can specify a custom table by defining a ``__table__`` property on your model:
.. code-block:: python
class User(Model):
__table__ = 'my_users'
The ORM will also assume that each table has a primary key column named ``id``.
You can define a ``__primary_key__`` property to override this convention.
Likewise, you can define a ``__connection__`` property to override the name of the database
connection that should be used when using the model.
Once a model is defined, you are ready to start retrieving and creating records in your table.
Note that you will need to place ``updated_at`` and ``created_at`` columns on your table by default.
If you do not wish to have these columns automatically maintained,
set the ``__timestamps__`` property on your model to ``False``.
Retrieving all models
---------------------
.. code-block:: python
users = User.all()
Retrieving a record by primary key
----------------------------------
.. code-block:: python
user = User.find(1)
print(user.name)
Querying using models
---------------------
.. code-block:: python
users = User.where('votes', '>', 100).take(10).get()
for user in users:
print(user.name)
Aggregates
----------
You can also use the query builder aggregate functions:
.. code-block:: python
count = User.where('votes', '>', 100).count()
If you feel limited by the builder's fluent interface, you can use the ``where_raw`` method:
.. code-block:: python
users = User.where_raw('age > ? and votes = 100', [25]).get()
Chunking Results
----------------
If you need to process a lot of records, you can use the ``chunk`` method to avoid
consuming a lot of RAM:
.. code-block:: python
for users in User.chunk(100):
for user in users:
# ...
Specifying the query connection
-------------------------------
You can specify which database connection to use when querying a model by using the ``on`` method:
.. code-block:: python
user = User.on('connection-name').find(1)
If you are using read / write connections, you can force the query to use the "write" connection
with the following method:
.. code-block:: python
user = User.on_write_connection().find(1)
Mass assignment
===============
When creating a new model, you pass attributes to the model constructor.
These attributes are then assigned to the model via mass-assignment.
Though convenient, this can be a serious security concern when passing user input into a model,
since the user is then free to modify **any** and **all** of the model's attributes.
For this reason, all models protect against mass-assignment by default.
To get started, set the ``__fillable__`` or ``__guarded__`` properties on your model.
Defining fillable attributes on a model
---------------------------------------
The ``__fillable__`` property specifies which attributes can be mass-assigned.
.. code-block:: python
class User(Model):
__fillable__ = ['first_name', 'last_name', 'email']
Defining guarded attributes on a model
--------------------------------------
The ``__guarded__`` is the inverse and acts as "blacklist".
.. code-block:: python
class User(Model):
__guarded__ = ['id', 'password']
You can also block **all** attributes from mass-assignment:
.. code-block:: python
__guarded__ = ['*']
Insert, update and delete
=========================
Saving a new model
------------------
To create a new record in the database, simply create a new model instance and call the ``save`` method.
.. code-block:: python
user = User()
user.name = 'John'
user.save()
You can also use the ``create`` method to save a model in a single line, but you will need to specify
either the ``__fillable__`` or ``__guarded__`` property on the model since all models are protected against
mass-assigment by default.
After saving or creating a new model with auto-incrementing IDs, you can retrieve the ID by accessing
the object's ``id`` attribute:
.. code-block:: python
inserted_id = user.id
Using the create method
-----------------------
.. code-block:: python
# Create a new user in the database
user = User.create(name='John')
# Retrieve the user by attributes, or create it if it does not exist
user = User.first_or_create(name='John')
# Retrieve the user by attributes, or instantiate it if it does not exist
user = User.first_or_new(name='John')
Updating a retrieved model
--------------------------
.. code-block:: python
user = User.find(1)
user.name = 'Foo'
user.save()
You can also run updates as queries against a set of models:
.. code-block:: python
affected_rows = User.where('votes', '>', 100).update(status=2)
..
TODO: push method
Deleting an existing model
--------------------------
To delete a model, simply call the ``delete`` model:
.. code-block:: python
user = User.find(1)
user.delete()
Deleting an existing model by key
---------------------------------
.. code-block:: python
User.destroy(1)
User.destroy(1, 2, 3)
You can also run a delete query on a set of models:
.. code-block:: python
affected_rows = User.where('votes', '>' 100).delete()
Updating only the model's timestamps
------------------------------------
If you want to only update the timestamps on a model, you can use the ``touch`` method:
.. code-block:: python
user.touch()
Timestamps
==========
By default, the ORM will maintain the ``created_at`` and ``updated_at`` columns on your database table
automatically. Simply add these ``timestamp`` columns to your table. If you do not wish for the ORM to maintain
these columns, just add the ``__timestamps__`` property:
.. code-block:: python
class User(Model):
__timestamps__ = False
Providing a custom timestamp format
-----------------------------------
If you whish to customize the format of your timestamps (the default is the ISO Format) that will be returned when using the ``to_dict``
or the ``to_json`` methods, you can override the ``get_date_format`` method:
.. code-block:: python
class User(Model):
def get_date_format():
return 'DD-MM-YY'
Converting to dictionaries / JSON
=================================
Converting a model to a dictionary
----------------------------------
When building JSON APIs, you may often need to convert your models and relationships to dictionaries or JSON.
So, Eloquent includes methods for doing so. To convert a model and its loaded relationship to a dictionary,
you may use the ``to_dict`` method:
.. code-block:: python
user = User.with_('roles').first()
return user.to_dict()
Note that entire collections of models can also be converted to dictionaries:
.. code-block:: python
return User.all().to_dict()
Converting a model to JSON
--------------------------
To convert a model to JSON, you can use the ``to_json`` method!
.. code-block:: python
return User.find(1).to_json()
Query Builder
=============
Introduction
------------
The database query builder provides a fluent interface to create and run database queries.
It can be used to perform most database operations in your application, and works on all supported database systems.
Selects
-------
Retrieving all row from a table
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
users = db.table('users').get()
for user in users:
print(user['name'])
Chunking results from a table
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
for users in db.table('users').chunk(100):
for user in users:
# ...
Retrieving a single row from a table
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
user = db.table('users').where('name', 'John').first()
print(user['name'])
Retrieving a single column from a row
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
user = db.table('users').where('name', 'John').pluck('name')
Retrieving a list of column values
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
roles = db.table('roles').lists('title')
This method will return a list of role titles. It can return a dictionary
if you pass an extra key parameter.
.. code-block:: python
roles = db.table('roles').lists('title', 'name')
Specifying a select clause
~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
users = db.table('users').select('name', 'email').get()
users = db.table('users').distinct().get()
users = db.table('users').select('name as user_name').get()
Adding a select clause to an existing query
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
query = db.table('users').select('name')
users = query.add_select('age').get()
Using where operators
~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
users = db.table('users').where('age', '>', 25).get()
Or statements
~~~~~~~~~~~~~
.. code-block:: python
users = db.table('users').where('age', '>', 25).or_where('name', 'John').get()
Using Where Between
~~~~~~~~~~~~~~~~~~~
.. code-block:: python
users = db.table('users').where_between('age', [25, 35]).get()
Using Where Not Between
~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
users = db.table('users').where_not_between('age', [25, 35]).get()
Using Where In
~~~~~~~~~~~~~~
.. code-block:: python
users = db.table('users').where_in('id', [1, 2, 3]).get()
users = db.table('users').where_not_in('id', [1, 2, 3]).get()
Using Where Null to find records with null values
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
users = db.table('users').where_null('updated_at').get()
Order by, group by and having
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
query = db.table('users').order_by('name', 'desc')
query = query.group_by('count')
query = query.having('count', '>', 100)
users = query.get()
Offset and limit
~~~~~~~~~~~~~~~~
.. code-block:: python
users = db.table('users').skip(10).take(5).get()
users = db.table('users').offset(10).limit(5).get()
Joins
-----
The query builder can also be used to write join statements.
Basic join statement
~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
db.table('users') \
.join('contacts', 'users.id', '=', 'contacts.user_id') \
.join('orders', 'users.id', '=', 'orders.user_id') \
.select('users.id', 'contacts.phone', 'orders.price') \
.get()
Left join statement
~~~~~~~~~~~~~~~~~~~
.. code-block:: python
db.table('users').left_join('posts', 'users.id', '=', 'posts.user_id').get()
You can also specify more advance join clauses:
.. code-block:: python
clause = JoinClause('contacts').on('users.id', '=', 'contacts.user_id').or_on(...)
db.table('users').join(clause).get()
If you would like to use a "where" style clause on your joins,
you may use the ``where`` and ``or_where`` methods on a join.
Instead of comparing two columns, these methods will compare the column against a value:
.. code-block:: python
clause = JoinClause('contacts').on('users.id', '=', 'contacts.user_id').where('contacts.user_id', '>', 5)
db.table('users').join(clause).get()
Advanced where
--------------
Sometimes you may need to create more advanced where clauses such as "where exists" or nested parameter groupings.
It is pretty easy to do with the Eloquent query builder
Parameter grouping
~~~~~~~~~~~~~~~~~~
.. code-block:: python
db.table('users') \
.where('name', '=', 'John') \
.or_where(
db.query().where('votes', '>', 100).where('title', '!=', 'admin')
).get()
The query above will produce the following SQL:
.. code-block:: sql
SELECT * FROM users WHERE name = 'John' OR (votes > 100 AND title != 'Admin')
Exists statement
~~~~~~~~~~~~~~~~
.. code-block:: python
db.table('users').where_exists(
db.table('orders').select(db.raw(1)).where_raw('order.user_id = users.id')
)
The query above will produce the following SQL:
.. code-block:: sql
SELECT * FROM users
WHERE EXISTS (
SELECT 1 FROM orders WHERE orders.user_id = users.id
)
Aggregates
----------
The query builder also provides a variety of aggregate methods, `
such as ``count``, ``max``, ``min``, ``avg``, and ``sum``.
.. code-block:: python
users = db.table('users').count()
price = db.table('orders').max('price')
price = db.table('orders').min('price')
price = db.table('orders').avg('price')
total = db.table('users').sum('votes')
Raw expressions
---------------
Sometimes you may need to use a raw expression in a query.
These expressions will be injected into the query as strings, so be careful not to create any SQL injection points!
To create a raw expression, you may use the ``raw()`` method:
.. code-block:: python
db.table('users') \
.select(db.raw('count(*) as user_count, status')) \
.where('status', '!=', 1) \
.group_by('status') \
.get()
Inserts
-------
Insert records into a table
~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
db.table('users').insert(email='foo@bar.com', votes=0)
db.table('users').insert({
'email': 'foo@bar.com',
'votes': 0
})
It is important to note that there is two notations available.
The reason is quite simple: the dictionary notation, though a little less practical, is here to handle
columns names which cannot be passed as keywords arguments.
Inserting records into a table with an auto-incrementing ID
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If the table has an auto-incrementing id, use ``insert_get_id`` to insert a record and retrieve the id:
.. code-block:: python
id = db.table('users').insert_get_id({
'email': 'foo@bar.com',
'votes': 0
})
Inserting multiple record into a table
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
db.table('users').insert([
{'email': 'foo@bar.com', 'votes': 0},
{'email': 'bar@baz.com', 'votes': 0}
])
Updates
-------
Updating records
~~~~~~~~~~~~~~~~
.. code-block:: python
db.table('users').where('id', 1).update(votes=1)
db.table('users').where('id', 1).update({'votes': 1})
Like the ``insert`` statement, there is two notations available.
The reason is quite simple: the dictionary notation, though a little less practical, is here to handle
columns names which cannot be passed as keywords arguments.
Incrementing or decrementing the value of a column
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
db.table('users').increment('votes') # Increment the value by 1
db.table('users').increment('votes', 5) # Increment the value by 5
db.table('users').decrement('votes') # Decrement the value by 1
db.table('users').decrement('votes', 5) # Decrement the value by 5
You can also specify additional columns to update:
.. code-block:: python
db.table('users').increment('votes', 1, name='John')
Deletes
-------
Deleting records
~~~~~~~~~~~~~~~~
.. code-block:: python
db.table('users').where('age', '<', 25).delete()
Delete all records
~~~~~~~~~~~~~~~~~~
.. code-block:: python
db.table('users').delete()
Truncate
~~~~~~~~
.. code-block:: python
db.table('users').truncate()
Unions
------
The query builder provides a quick and easy way to "union" two queries:
.. code-block:: python
first = db.table('users').where_null('first_name')
users = db.table('users').where_null('last_name').union(first).get()
The ``union_all`` method is also available.
.. _read_write_connections:
Read / Write connections
========================
Sometimes you may wish to use one database connection for SELECT statements,
and another for INSERT, UPDATE, and DELETE statements. Eloquent makes this easy,
and the proper connections will always be used whether you use raw queries, the query
builder or the actual ORM
Here is an example of how read / write connections should be configured:
.. code-block:: python
config = {
'mysql': {
'read': [
'host': '192.168.1.1'
],
'read': [
'host': '192.168.1.2'
],
'driver': 'mysql',
'database': 'database',
'username': 'root',
'password': '',
'prefix': ''
}
}
Note that two keys have been added to the configuration dictionary: ``read`` and ``write``.
Both of these keys have dictionary values containing a single key: ``host``.
The rest of the database options for the ``read`` and ``write`` connections
will be merged from the main ``mysql`` dictionary. So, you only need to place items
in the ``read`` and ``write`` dictionaries if you wish to override the values in the main dictionary.
So, in this case, ``192.168.1.1`` will be used as the "read" connection, while ``192.168.1.2``
will be used as the "write" connection. The database credentials, prefix, character set,
and all other options in the main ``mysql`` dictionary will be shared across both connections.
Database transactions
=====================
To run a set of operations within a database transaction, you can use the ``transaction`` method
which is a context manager:
.. code-block:: python
with db.transaction():
db.table('users').update({votes: 1})
db.table('posts').delete()
.. note::
Any exception thrown within a transaction block will cause the transaction to be rolled back
automatically.
Sometimes you may need to start a transaction yourself:
.. code-block:: python
db.begin_transaction()
You can rollback a transaction with the ``rollback`` method:
.. code-block:: python
db.rollback()
You can also commit a transaction via the ``commit`` method:
.. code-block:: python
db.commit()
By default, all underlying DBAPI connections are set to be in autocommit mode
meaning that you don't need to explicitly commit after each operation.
Accessing connections
=====================
When using multiple connections, you can access them via the ``connection()`` method:
.. code-block:: python
users = db.connection('foo').table('users').get()
You also can access the raw, underlying dbapi connection instance:
.. code-block:: python
db.connection().get_connection()
Sometimes, you may need to reconnect to a given database:
.. code-block:: python
db.reconnect('foo')
If you need to disconnect from the given database, use the ``disconnect`` method:
.. code-block:: python
db.disconnect('foo')
نحوه نصب
نصب پکیج whl eloquent-0.5:
pip install eloquent-0.5.whl
نصب پکیج tar.gz eloquent-0.5:
pip install eloquent-0.5.tar.gz