Working with Activity API in Open Event API Server


Recently, I added the Activities API with documentation and dredd tests for the same in
Open Event API Server. The Activity Model in the Open Event Server is basically a log of all the things that happen while the server is running, like – event updates, speaker additions, invoice generations and other similar things. This blogpost explains how to implement Activity API in the Open Event API Server’s nextgen branch. In the Open Event Server, we first add the endpoints, then document these so that the consumers ( Open Event Orga App, Open Event Frontend) find it easy to work with all the endpoints.

We also test the documentation against backend implementation to ensure that a end-developer who is working with the APIs is not misled to believe what each endpoint actually does in the server.

We also test the documentation against backend implementation to ensure that a end-developer who is working with the APIs is not misled to believe what each endpoint actually does in the server.
The Activities API endpoints are based on the Activity database model. The Activity table has four columns – 
id, actor, time, action, the names are self-explanatory. Now for the API schema, we need to make fields corresponding these columns.
Since id is auto generated, we do not need to add it as a field for API. Also the activity model’s __init__ method stamps time with the current system time. So this field is also not required in the API fields. We are left with two fields- actor and action.

Defining API Schema

Next, we define the API Schema class for Activities model. This will involve a Meta class and fields for the class.The Meta class contains the metadata of the class. This includes details about type_,

self_view, self_view_kwargs and an inflect parameter to dasherize the input fields from request body.

We define the four fields – id, actor, time and action according to marshmallow fields based on the data type and parameters from the activities model. Since id, actor and action are string columns and time is a DateTime column, the fields are written as following:

The id field is marked as dump only because it is a read-only type field. The other fields are marked with allow_none as they are all non-required field.

ActivityList Class:
The activity list class will provide us with the endpoint: “/v1/activities”

This endpoint will list all the activities. Since we wanted only GET requests to be working for this, so defined method = [‘GET’, ] for ResourceList. The activities are to be internally created based on different actions like creating an event, updating an event, adding speakers to sessions and likewise. Since the activities are to be shown only to the server admin, 
is_admin permission is used from the permission manager.

ActivityDetail Class:

The activity detail gives methods to work with an activity based on the activity id.
The endpoint provided is :  ‘/v1/activity/<int:activity_id>’

Since this is also an admin-only accessible GET only endpoint the following was written:

Writing Documentation:

The documentation is written using API Blueprint. Since we have two endpoints to document : /v1/activities and /v1/activities/<int:activity_id> both GET only.

So we begin by defining the ‘Group Activities’ , under which we first list  ‘Activity Collection’ which essentially is the Activity List class.

For this class, we have the endpoint:  /v1/activities. This is added for GET request. The parameters – actor, time and action are described along with description, type and whether they are required or not.

The request headers are written as part of the docs followed by the expected response.

Next we write the ‘Activity Details’ which represents the ActivityDetail class. Here the endpoint /v1/activities/<int:activity_id> is documented for GET. The parameter here is activity_id, which is the id of the activity to get the details of.

Writing DREDD Test for Documentation

To imitate the request responses, we need a faker script which creates an object of the the class we are testing the docs for then makes the request. For this we use FactoryBoy and dredd hooks to insert data into the database.

Defining Factory Model for Activity db model

The above is the factory model for activity model. It is derived from

factory.alchemy.SQLAlchemyModelFactory. The meta class defines the db model and sqlalchemy session to be used. The actor and action have dummy strings as part of the request body.

Writing Hooks
Now to test these endpoints we need to add objects to the database so that the GET requests have an object to fetch. This is done by dredd hooks. Before each request, an object of the corresponding factory class is initialised and committed into the database. Thus a dummy object is available for dredd to test on. The request is made and the real output is compared with the expected output written in the API Blueprint documentation.

This is what the hooks look like for  this endpoint: GET /activities

Now if the expected responses and actual responses match, the dredd test successfully passes. This dredd test in run on each build of the project on Travis to ensure that documented code does exactly what is says!

This concludes the process to write an API right from Schema to Resources and Documentation and Dredd tests.

Additional Resources:

Using API Blueprint with Yaydoc

As part of extending the capability of Yaydoc to document APIs, this week we integrated API Blueprint with Yaydoc. Now we can parse apib files and add the parsed content to the generated documentation. From the official Homepage of API Blueprint,

API Blueprint is simple and accessible to everybody involved in the API lifecycle. Its syntax is concise yet expressive. With API Blueprint you can quickly design and prototype APIs to be created or document and test already deployed mission-critical APIs. It is a documentation-oriented web API description language. The API Blueprint is essentially a set of semantic assumptions laid on top of the Markdown syntax used to describe a web API.

To Integrate API Blueprint with Yaydoc, we used an sphinx extension named sphinxcontrib-apiblueprint. This extension can directly translate text in API Blueprint format into docutils nodes. The advantage with this approach as compared to using tools like aglio is that the generated html fits in nicely with the already existent theme. Though we may in future provide ability to generate html using tools like aglio if the user prefers. Adding an extension to sphinx is very easy. In the conf.py template, we added the extension to the already enabled list of extensions.

extensions += [‘sphinxcontrib.apiblueprint’]

The above extension provides a directive apiblueprint which can be then used to include apib files. The directive is very similar to the built in include directive. The difference is just that it should be only be used to include files in API Blueprint format. You can see an example below of how to use this directive.

.. apiblueprint:: <path to apib file>

Although this is enough for projects which use the ResT markup format, This cannot be used with projects using markdown as the primary markup format, since markdown doesn’t support the concept of directives. To solve this, we used the eval_rst block provided by recommonmark in Yaydoc. It allows users to embed valid ReST within markdown and recommonmark will properly parse the embedded text as ReST. Now a user can use this to use directives within markdown. You can see an example below.

```eval_rst
.. apiblueprint:: <path to apib file>
```

In order to implement this, we used the AutoStructify class provided by recommonmark. Here’s a snippet from our conf.py template. Note that this does have far reaching effects. Now users would be able to use this to add constructs like toctree in markdown which wasn’t possible before.

from recommonmark.transform import AutoStructify

def setup(app):
    app.add_config_value('recommonmark_config', {
    'enable_eval_rst': True,
    }, True)
    app.add_transform(AutoStructify)

Let’s see all of this in action. Here’s a preview of a generated documentation with API Blueprint using Yaydoc.

Resources

Rendering Open Event Server’s API-Blueprint document

After writing the FOSSASIA‘s Open Event Server project API- Blueprint Document manually, we wanted to know how we could render the document, how to check it in an HTML-client friendly format and how to make it change the look as we go. In order to do that, we found two rendering ways.

They are:

1) The apiary editor:

This editor helps us to render API blueprints and print them in user readable API documented format. When we create the API blueprint manually, we always follow the pattern write an api blueprint i.e the name and metadata, then followed by resource groups and actions, which was already discussed in the last blog. In order to use the apiary editor, we start off by creating our first project. Initially during the our first use of this editor, we will get a default “polls and vote” example api project. This is a template we can use as guide. The pole/vote api looks something like this in the editor mode:

 

Apiary has a facility to test an API, document an API, inspect an API or simply edit an API. We first start off by creating a project “open-event-api”. Next, in the editor mode of the apiary, we add the contents of our api-blueprint documents.
Here is an example of how USERS API is rendered. If we get our request and response correctly, on clicking List All Users we will get a good 200 response like this in the editor:

However, if we tend to go off format with the api-blueprint, we get an invalid error:

The final rendering and how the API result can be seen in the document mode with the respective API’s request and response.
The document mode request and response look like this:

This rendered doc can be viewed publicly with the link got in the document mode. Similarly, we test it out in the editor for the rest of the ap. This is a simple way to render your api blueprint.

2)  The aglio renderer:

Since API blueprint is presented in the form of .apib format, the con side of it is it is not easily viewable by viewers. Even though we use apiary, view the rendered docs along with getting a shareable link, we would surely like the docs for our API server to be hosted in our server as well. So, we use Aglio exactly to do that .

It is an API Blueprint renderer which supports multiple themes. It converts the apib file into user readable formats such as pdf, html, etc. Here since we want to host it as a webpage, we render it in the form of .html.  It outputs static HTML of the result and can be served by any web host. Since API Blueprint is a Markdown-based document format, this lets us write API descriptions and documentation in a simple and straightforward way.
An example of how aglio rendered document in a three column format looks like:

The best thing about Aglio is not only does it support a lot many theme and templates, but it also allows you to provide your own custom theme and template to render the html file from the api blueprint.

How to use aglio renderer:

  • We first follow up with installation:
npm install -g aglio
  • After installation, we go to the folder the .apib file is stored and generate the HTML. There are 5 built in themes available with two column and three column layout. They are:
# Default theme
aglio -i input.apib -o output.html

-> This command takes as input the input.apib file as API Blueprint and creates a rendered output file named output.html.

 

# Use three-column layout
aglio -i input.apib --theme-template triple -o output.html

-> This command takes as input the input.apib file as API Blueprint and creates a rendered output file named output.html. However it uses the theme-template flag. The theme-template flag is used to define whether the layout of the rendered html is two column or three column. In this command, it is set as triple which means three column.

# Built-in color scheme
aglio --theme-variables slate -i input.apib -o output.html

-> Aglio has different color schemes that you can use while rendering the docs html file. Some of them are Olio, Streak, Slate, etc.

# Customize a built-in style
aglio --theme-style default --theme-style ./my-style.less -i input.apib -o output.html

-> Suppose you want to provide a syntactical style sheet such as SASS, LESS, etc. so as to define your own styling. You can do that as given in the above example. The my-style.less is a user defined syntactical stylesheet. This is then used to provide styling for the output file rendered.

# Custom layout template
aglio --theme-template /path/to/template.jade -i input.apib -o output.html

-> You can write your own custom layout template in a template.jade file and use that for generating the output.html instead of two or three column layout.

We run the build-in color scheme: aglio –theme-variables slate -i api_blueprint.apib -o output.html to generate our Open Event Server api document which we have something like this:

You can visit the live version of FOSSASIA‘s Open Event Server API Document right here: https://api.eventyay.com/