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How to create REST API using Pyramid

#rest #api #pyramid #python

Pyramid is a lightweight python web framework following MVC architectural pattern. In this article, we will set up a web application and API using Pyramid.

Pyramid is a suitable framework for large scale MVC applications and it comes with flexible bootstrapping tools.

Cornice, a library from Mozilla, makes it easy to develop RESTful web services with pyramid.

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Installation

First we create a virtual environment which helps us in separating project specific python packages installations from other projects. After activating the virtual environment, we install pyramid framework using command:

pip install pyramid
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Create models

We create a models.py file with a class Note which maps to the data table storing all the values of notes.

# pyramidapp/models.py  class Note(Base): __tablename__ = 'Note' id = Column(Integer, primary_key=True) title = Column(Text) description = Column(Text) create_at = Column(Text) create_by = Column(Text) priority = Column(Integer) def __init__(self, title, description, create_at ,create_by, priority): self.title = title self.description = description self.create_at = create_at self.create_by = create_by self.priority = priority @classmethod def from_json(cls, data): return cls(**data) def to_json(self): to_serialize = ['id', 'title', 'description', 'create_at', 'create_by', 'priority'] d = {} for attr_name in to_serialize: d[attr_name] = getattr(self, attr_name) return d
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Views

In views.py file, we add our services for different API requests.

@resource(collection_path='/notes', path='/notes/{id}') class NoteView(object): def __init__(self, request): self.request = request def collection_get(self): return { 'notes': [ {'id': note.id, 'title': note.title, 'description': note.description, 'create_at': note.create_at, 'create_by': note.create_by, 'priority': note.priority} for note in DBSession.query(Note) ] } def get(self): try: return DBSession.query(Note).get( int(self.request.matchdict['id'])).to_json() except: return {} def collection_post(self): note = self.request.json DBSession.add(Note.from_json(note)) def put(self): try: obj=DBSession.query(Note).filter(Note.id==self.request.matchdict['id']) obj.update(self.request.json) return {'notes': [ {'id': note.id, 'title': note.title, 'description': note.description, 'create_at': note.create_at, 'create_by': note.create_by, 'priority': note.priority} for note in DBSession.query(Note) ] } except: return {'result': 'No object found'} def delete(self): obj=DBSession.query(Note).filter(Note.id==self.request.matchdict['id']).first() DBSession.delete(obj) return {'notes': [ {'id': note.id, 'title': note.title, 'description': note.description, 'create_at': note.create_at, 'create_by': note.create_by, 'priority': note.priority} for note in DBSession.query(Note) ] }
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Running the application

Create the database schema by executing:

python initialize_db.py
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Start the development server by:

python setup.py develop pserve note.ini --reload
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We can view the notes by navigating to the URL http://localhost:6543/notes in browser.

Open python shell and execute requests for API:

requests.post('http://localhost:6543/notes', headers={'Content-Type': 'application/json'}, data=json.dumps({ "title": "sample note one ", "create_at": "2017-08-23 00:00", "create_by": "apcelent", "description": "sample notes", "priority": 3, })) requests.put('http://localhost:6543/notes/1', headers={'Content-Type': 'application/json'}, data=json.dumps({ "title": "sample note edit ", "create_at": "2017-08-23 00:00", "create_by": "apcelent", "description": "sample notes edit", "priority": 4, })) requests.delete('http://localhost:6543/notes/1')
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The source code can be found on github

Hope the article was of help!

The article originally appeared on Apcelent Tech Blog.

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