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diff --git a/docs/tutorials/wiki2/definingmodels.rst b/docs/tutorials/wiki2/definingmodels.rst index 7aa2214fc..6520613ea 100644 --- a/docs/tutorials/wiki2/definingmodels.rst +++ b/docs/tutorials/wiki2/definingmodels.rst @@ -1,95 +1,263 @@ +.. _wiki2_defining_the_domain_model: + ========================= Defining the Domain Model ========================= -The first change we'll make to our stock paster-generated application will be -to define a :term:`domain model` constructor representing a wiki page. We'll -do this inside our ``models.py`` file. +The first change we'll make to our stock ``pcreate``-generated application will +be to define a wiki page :term:`domain model`. + +.. note:: -The source code for this tutorial stage can be browsed at -`http://github.com/Pylons/pyramid/tree/master/docs/tutorials/wiki2/src/models/ -<http://github.com/Pylons/pyramid/tree/master/docs/tutorials/wiki2/src/models/>`_. + There is nothing special about the filename ``user.py`` or ``page.py`` except + that they are Python modules. A project may have many models throughout its + codebase in arbitrarily named modules. Modules implementing models often + have ``model`` in their names or they may live in a Python subpackage of + your application package named ``models`` (as we've done in this tutorial), + but this is only a convention and not a requirement. -Making Edits to ``models.py`` ------------------------------ -.. note:: +Declaring dependencies in our ``setup.py`` file +=============================================== - There is nothing automagically special about the filename - ``models.py``. A project may have many models throughout its - codebase in arbitrarily-named files. Files implementing models - often have ``model`` in their filenames (or they may live in a - Python subpackage of your application package named ``models``) , - but this is only by convention. +The models code in our application will depend on a package which is not a +dependency of the original "tutorial" application. The original "tutorial" +application was generated by the ``pcreate`` command; it doesn't know about our +custom application requirements. -The first thing we want to do is remove the stock ``MyModel`` class from the -generated ``models.py`` file. The ``MyModel`` class is only a sample and -we're not going to use it. +We need to add a dependency, the ``bcrypt`` package, to our ``tutorial`` +package's ``setup.py`` file by assigning this dependency to the ``requires`` +parameter in the ``setup()`` function. -Next, we'll remove the :class:`sqlalchemy.Unicode` import and replace it -with :class:`sqlalchemy.Text`. +Open ``tutorial/setup.py`` and edit it to look like the following: -.. literalinclude:: src/models/tutorial/models.py - :lines: 5 +.. literalinclude:: src/models/setup.py + :linenos: + :emphasize-lines: 12 + :language: python + +Only the highlighted line needs to be added. + + +Running ``pip install -e .`` +============================ + +Since a new software dependency was added, you will need to run ``pip install +-e .`` again inside the root of the ``tutorial`` package to obtain and register +the newly added dependency distribution. + +Make sure your current working directory is the root of the project (the +directory in which ``setup.py`` lives) and execute the following command. + +On UNIX: + +.. code-block:: bash + + $ cd tutorial + $ $VENV/bin/pip install -e . + +On Windows: + +.. code-block:: doscon + + c:\pyramidtut> cd tutorial + c:\pyramidtut\tutorial> %VENV%\Scripts\pip install -e . + +Success executing this command will end with a line to the console something +like this:: + + Successfully installed bcrypt-2.0.0 cffi-1.5.2 pycparser-2.14 tutorial-0.0 + + +Remove ``mymodel.py`` +--------------------- + +Let's delete the file ``tutorial/models/mymodel.py``. The ``MyModel`` class is +only a sample and we're not going to use it. + + +Add ``user.py`` +--------------- + +Create a new file ``tutorial/models/user.py`` with the following contents: + +.. literalinclude:: src/models/tutorial/models/user.py :linenos: :language: py -Then, we'll add a ``Page`` class. Because this is a SQLAlchemy -application, this class should inherit from an instance of -:class:`sqlalchemy.ext.declarative.declarative_base`. Declarative -SQLAlchemy models are easier to use than directly-mapped ones. +This is a very basic model for a user who can authenticate with our wiki. + +We discussed briefly in the previous chapter that our models will inherit from +an SQLAlchemy :func:`sqlalchemy.ext.declarative.declarative_base`. This will +attach the model to our schema. + +As you can see, our ``User`` class has a class-level attribute +``__tablename__`` which equals the string ``users``. Our ``User`` class will +also have class-level attributes named ``id``, ``name``, ``password_hash``, +and ``role`` (all instances of :class:`sqlalchemy.schema.Column`). These will +map to columns in the ``users`` table. The ``id`` attribute will be the primary +key in the table. The ``name`` attribute will be a text column, each value of +which needs to be unique within the column. The ``password_hash`` is a nullable +text attribute that will contain a securely hashed password [1]_. Finally, the +``role`` text attribute will hold the role of the user. + +There are two helper methods that will help us later when using the user +objects. The first is ``set_password`` which will take a raw password and +transform it using bcrypt_ into an irreversible representation, a process known +as "hashing". The second method, ``check_password``, will allow us to compare +the hashed value of the submitted password against the hashed value of the +password stored in the user's record in the database. If the two hashed values +match, then the submitted password is valid, and we can authenticate the user. + +We hash passwords so that it is impossible to decrypt them and use them to +authenticate in the application. If we stored passwords foolishly in clear +text, then anyone with access to the database could retrieve any password to +authenticate as any user. + -.. literalinclude:: src/models/tutorial/models.py - :pyobject: Page +Add ``page.py`` +--------------- + +Create a new file ``tutorial/models/page.py`` with the following contents: + +.. literalinclude:: src/models/tutorial/models/page.py :linenos: - :language: python + :language: py + +As you can see, our ``Page`` class is very similar to the ``User`` defined +above, except with attributes focused on storing information about a wiki page, +including ``id``, ``name``, and ``data``. The only new construct introduced +here is the ``creator_id`` column, which is a foreign key referencing the +``users`` table. Foreign keys are very useful at the schema-level, but since we +want to relate ``User`` objects with ``Page`` objects, we also define a +``creator`` attribute as an ORM-level mapping between the two tables. +SQLAlchemy will automatically populate this value using the foreign key +referencing the user. Since the foreign key has ``nullable=False``, we are +guaranteed that an instance of ``page`` will have a corresponding +``page.creator``, which will be a ``User`` instance. + + +Edit ``models/__init__.py`` +--------------------------- + +Since we are using a package for our models, we also need to update our +``__init__.py`` file to ensure that the models are attached to the metadata. -As you can see, our ``Page`` class has a class level attribute -``__tablename__`` which equals the string ``'pages'``. This means that -SQLAlchemy will store our wiki data in a SQL table named ``pages``. Our Page -class will also have class-level attributes named ``id``, ``name`` and -``data`` (all instances of :class:`sqlalchemy.Column`). These will map to -columns in the ``pages`` table. The ``id`` attribute will be the primary key -in the table. The ``name`` attribute will be a text attribute, each value of -which needs to be unique within the column. The ``data`` attribute is a text -attribute that will hold the body of each page. - -We'll also remove our ``populate`` function. We'll inline the populate step -into ``initialize_sql``, changing our ``initialize_sql`` function to add a -FrontPage object to our database at startup time. - -.. literalinclude:: src/models/tutorial/models.py - :pyobject: initialize_sql +Open the ``tutorial/models/__init__.py`` file and edit it to look like +the following: + +.. literalinclude:: src/models/tutorial/models/__init__.py :linenos: - :language: python + :language: py + :emphasize-lines: 8,9 -Here, we're using a slightly different binding syntax. It is otherwise -largely the same as the ``initialize_sql`` in the paster-generated -``models.py``. +Here we align our imports with the names of the models, ``Page`` and ``User``. -Our ``DBSession`` assignment stays the same as the original generated -``models.py``. -Looking at the Result of all Our Edits to ``models.py`` -------------------------------------------------------- +Edit ``scripts/initializedb.py`` +-------------------------------- -The result of all of our edits to ``models.py`` will end up looking -something like this: +We haven't looked at the details of this file yet, but within the ``scripts`` +directory of your ``tutorial`` package is a file named ``initializedb.py``. +Code in this file is executed whenever we run the ``initialize_tutorial_db`` +command, as we did in the installation step of this tutorial [2]_. -.. literalinclude:: src/models/tutorial/models.py +Since we've changed our model, we need to make changes to our +``initializedb.py`` script. In particular, we'll replace our import of +``MyModel`` with those of ``User`` and ``Page``. We'll also change the very end +of the script to create two ``User`` objects (``basic`` and ``editor``) as well +as a ``Page``, rather than a ``MyModel``, and add them to our ``dbsession``. + +Open ``tutorial/scripts/initializedb.py`` and edit it to look like the +following: + +.. literalinclude:: src/models/tutorial/scripts/initializedb.py :linenos: :language: python + :emphasize-lines: 18,44-57 + +Only the highlighted lines need to be changed. -Viewing the Application in a Browser ------------------------------------- + +Installing the project and re-initializing the database +------------------------------------------------------- + +Because our model has changed, and in order to reinitialize the database, we +need to rerun the ``initialize_tutorial_db`` command to pick up the changes +we've made to both the models.py file and to the initializedb.py file. See +:ref:`initialize_db_wiki2` for instructions. + +Success will look something like this: + +.. code-block:: bash + + 2016-04-09 02:49:51,711 INFO [sqlalchemy.engine.base.Engine:1192][MainThread] SELECT CAST('test plain returns' AS VARCHAR(60)) AS anon_1 + 2016-04-09 02:49:51,711 INFO [sqlalchemy.engine.base.Engine:1193][MainThread] () + 2016-04-09 02:49:51,712 INFO [sqlalchemy.engine.base.Engine:1192][MainThread] SELECT CAST('test unicode returns' AS VARCHAR(60)) AS anon_1 + 2016-04-09 02:49:51,712 INFO [sqlalchemy.engine.base.Engine:1193][MainThread] () + 2016-04-09 02:49:51,713 INFO [sqlalchemy.engine.base.Engine:1097][MainThread] PRAGMA table_info("pages") + 2016-04-09 02:49:51,714 INFO [sqlalchemy.engine.base.Engine:1100][MainThread] () + 2016-04-09 02:49:51,714 INFO [sqlalchemy.engine.base.Engine:1097][MainThread] PRAGMA table_info("users") + 2016-04-09 02:49:51,714 INFO [sqlalchemy.engine.base.Engine:1100][MainThread] () + 2016-04-09 02:49:51,715 INFO [sqlalchemy.engine.base.Engine:1097][MainThread] + CREATE TABLE users ( + id INTEGER NOT NULL, + name TEXT NOT NULL, + role TEXT NOT NULL, + password_hash TEXT, + CONSTRAINT pk_users PRIMARY KEY (id), + CONSTRAINT uq_users_name UNIQUE (name) + ) + + + 2016-04-09 02:49:51,715 INFO [sqlalchemy.engine.base.Engine:1100][MainThread] () + 2016-04-09 02:49:51,716 INFO [sqlalchemy.engine.base.Engine:686][MainThread] COMMIT + 2016-04-09 02:49:51,716 INFO [sqlalchemy.engine.base.Engine:1097][MainThread] + CREATE TABLE pages ( + id INTEGER NOT NULL, + name TEXT NOT NULL, + data INTEGER NOT NULL, + creator_id INTEGER NOT NULL, + CONSTRAINT pk_pages PRIMARY KEY (id), + CONSTRAINT uq_pages_name UNIQUE (name), + CONSTRAINT fk_pages_creator_id_users FOREIGN KEY(creator_id) REFERENCES users (id) + ) + + + 2016-04-09 02:49:51,716 INFO [sqlalchemy.engine.base.Engine:1100][MainThread] () + 2016-04-09 02:49:51,717 INFO [sqlalchemy.engine.base.Engine:686][MainThread] COMMIT + 2016-04-09 02:49:52,256 INFO [sqlalchemy.engine.base.Engine:646][MainThread] BEGIN (implicit) + 2016-04-09 02:49:52,257 INFO [sqlalchemy.engine.base.Engine:1097][MainThread] INSERT INTO users (name, role, password_hash) VALUES (?, ?, ?) + 2016-04-09 02:49:52,257 INFO [sqlalchemy.engine.base.Engine:1100][MainThread] ('editor', 'editor', b'$2b$12$APUPJvI/kKxrbQPyQehkR.ggoOM6fFYCZ07SFCkWGltl1wJsKB98y') + 2016-04-09 02:49:52,258 INFO [sqlalchemy.engine.base.Engine:1097][MainThread] INSERT INTO users (name, role, password_hash) VALUES (?, ?, ?) + 2016-04-09 02:49:52,258 INFO [sqlalchemy.engine.base.Engine:1100][MainThread] ('basic', 'basic', b'$2b$12$GeFnypuQpZyxZLH.sN0akOrPdZMcQjqVTCim67u6f89lOFH/0ddc6') + 2016-04-09 02:49:52,259 INFO [sqlalchemy.engine.base.Engine:1097][MainThread] INSERT INTO pages (name, data, creator_id) VALUES (?, ?, ?) + 2016-04-09 02:49:52,259 INFO [sqlalchemy.engine.base.Engine:1100][MainThread] ('FrontPage', 'This is the front page', 1) + 2016-04-09 02:49:52,259 INFO [sqlalchemy.engine.base.Engine:686][MainThread] COMMIT + + +View the application in a browser +--------------------------------- We can't. At this point, our system is in a "non-runnable" state; we'll need to change view-related files in the next chapter to be able to start the -application successfully. If you try to start the application, you'll wind -up with a Python traceback on your console that ends with this exception: +application successfully. If you try to start the application (see +:ref:`wiki2-start-the-application`), you'll wind up with a Python traceback on +your console that ends with this exception: .. code-block:: text ImportError: cannot import name MyModel This will also happen if you attempt to run the tests. + +.. _bcrypt: https://pypi.python.org/pypi/bcrypt + +.. [1] We are using the bcrypt_ package from PyPI to hash our passwords + securely. There are other one-way hash algorithms for passwords if + bcrypt is an issue on your system. Just make sure that it's an + algorithm approved for storing passwords versus a generic one-way hash. + +.. [2] The command is named ``initialize_tutorial_db`` because of the mapping + defined in the ``[console_scripts]`` entry point of our project's + ``setup.py`` file. |