Flask API - create nested json response group by field single table - python-3.x

Question

I have a basic API setup to do a basic Post and Get from a single table. I want to create a nested array though grouping by force_element_type
model.py
from db import db
from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy import text as sa_text
class ForceElementModel(db.Model):
__tablename__ = 'force_element'
__table_args__ = {'schema': 'force_element'}
force_element_id = db.Column(UUID(as_uuid=True), primary_key=True, server_default=sa_text("uuid_generate_v4()"))
name = db.Column(db.String(100), nullable=False)
force_element_type = db.Column(db.String(20), nullable=False)
def __init__(self, name, force_element_type):
self.name = name
self.force_element_type = force_element_type
def json(self):
return {'name': self.name, 'force_element_type': self.force_element_type}
#classmethod
def find_by_name(cls, name):
return cls.query.filter_by(name=name).first() # simple TOP 1 select
def save_to_db(self): # Upserting data
db.session.add(self)
db.session.commit() # Balla
def delete_from_db(self):
db.session.delete(self)
db.session.commit()
resource.py
from flask_restful import Resource, reqparse
#from flask_jwt import jwt_required
from models.force_element import ForceElementModel
class ForceElement(Resource):
parser = reqparse.RequestParser() # only allow price changes, no name changes allowed
parser.add_argument('force_element_type', type=str, required=True, help='This field cannot be left blank')
##jwt_required()
def post(self, name):
if ForceElementModel.find_by_name(name):
return {'message': "An Force Element with name '{}' already exists.".format(name)}, 400
data = ForceElement.parser.parse_args()
force_element = ForceElementModel(name, data['force_element_type'])
try:
force_element.save_to_db()
except:
return {"message": "An error occurred inserting the item."}, 500
return force_element.json(), 201
class ForceElementList(Resource):
##jwt_required()
def get(self):
return {'force_elements': [force_element.json() for force_element in ForceElementModel.query.all()]}
class ForceElementType(Resource):
##jwt_required()
def get(self):
The GET endpoint using ForceElementList returns
{
"force_elements": [
{
"name": "San Antonio",
"force_element_type": "ship"
},
{
"name": "Nimitz",
"force_element_type": "ship"
},
{
"name": "Nimitz- Starboard",
"force_element_type": "Crew"
},
{
"name": "Nimitz- Port",
"force_element_type": "Crew"
}
]
}
I don't know how to group by force_element_type and return
[
"ship": [
{
"name": "San Antonio",
"force_element_id": "xxx1"
},
{
"name": "Nimitz",
"force_element_id": "xxx2"
}],
"crew": [
{
"name": "Nimitz- Starboard",
"force_element_id": "yyy1"
},
{
"name": "Nimitz- Port",
"force_element_id": "yyy2"
}
]
]
How do I create this separate andpoint?

Answer 1

OK I got there, here is how I did it. Is there a better way?
Lesson one use an online parser to check the json format this is what I was actually aiming for and the square braket at then start had me scratching my head for a while
{
"ship": [
{
"name": "San Antonio",
"force_element_id": "xxx1"
},
{
"name": "Nimitz",
"force_element_id": "xxx2"
}],
"crew": [
{
"name": "Nimitz- Starboard",
"force_element_id": "yyy1"
},
{
"name": "Nimitz- Port",
"force_element_id": "yyy2"
}]
}
This code creates the correct format for the output
class ForceElementType(Resource):
##jwt_required()
def get(self):
types = {}
force_elements = ForceElementModel.query.order_by(ForceElementModel.force_element_type.desc()).all()
for force_element in force_elements:
nested = {'name': force_element.name, 'force_element_id': str(force_element.force_element_id)}
print(nested)
if not force_element.force_element_type in types:
types[force_element.force_element_type] = []
types[force_element.force_element_type].append(nested)
response = types