How can I retrieve data using PyMongo?

Question

I have read the tutorials and because I am using three seperate things: 1. Flask as a server 2. PyMongo as a MongoDB driver 3. PyMODM as a schema creator

I got confused already.

First, I have defined the Schema using PyMODM:

from pymongo import TEXT
from pymongo.operations import IndexModel
from pymodm import connect, fields, MongoModel, EmbeddedMongoModel

class GoalPosition(EmbeddedMongoModel):
    x = fields.IntegerField()
    y = fields.IntegerField()

class GoalOrientation(EmbeddedMongoModel):
    x = fields.IntegerField()

class Goal(EmbeddedMongoModel):
    position = fields.EmbeddedDocumentField(GoalPosition)
    orientation = fields.EmbeddedDocumentField(GoalOrientation)

class Path(MongoModel):
    path = fields.EmbeddedDocumentListField(Goal)

From the above, my idea is to make two types of schemas: Goal and Path. At the end, Goal would look like this:

{
    "position": {
        "x": "1",
        "y": "6"
    },
    "orientation": {
        "x": "0"
    }
}

And Path will be a list of Goals. Having my schema, the big question is, how can I use that to communicate with my MongoDB database? Here is my small server code:

from flask import Flask, render_template, flash, redirect, url_for, session, request, logging
from flask_pymongo import PyMongo
from flask import jsonify


app = Flask(__name__)
app.config["MONGO_URI"] = "mongodb+srv://user:pass@cluster0-qhfvu.mongodb.net/test?retryWrites=true"
mongo = PyMongo(app)

@app.route('/goal', methods=['GET', 'POST'])
def goals():
    if request.method == 'GET':
        goals = mongo.db.goals.find()
        return jsonify(goals)

    elif request.method == 'POST':
        position = request.body.position
        orientation = request.body.orientation
        print position
        flash("Goal added")

@app.route('/goal/<id>')
def goal(id):
    goal = mongo.db.goals.find_one_or_404({"_id" : id})
    return jsonify(goal)

So by focusing only on GET method at route '/goal', how can I retrieve all the Goal messages from my database?

Also, I want to know how can I retrieve a last Goal message at '/goal/' ?

I don't understand your question. You're already doing that. Where are you having trouble? — Daniel Roseman, Dec 18 '18 at 11:31
@DanielRoseman Are you saying that my code is correct? But how can flask server and pymongo know what "mongo.db.goals.find()" is? — Steve Martin, Dec 18 '18 at 11:33

score 1 · Answer 1 · answered Dec 18 '18 at 20:06

def goals():
    if request.method == 'GET':
        goals = mongo.db.goals.find()
        return jsonify(goals)

You are already retrieving all the records in goals collection. Below example will give you single most updated record.

def goals():
        if request.method == 'GET':
        goals = mongo.db.goals.find().sort({'_id',-1}).limit(1)
        return jsonify(goals)

.

def goals():
        if request.method == 'GET':
        goals = mongo.db.goals.find().sort({'_id',-1})
        return jsonify(goals)

Above example will return list of all data in goals collection in descending order means last updates will be on top

To Find

mongo.db.goals.find_one({"_id": ObjectId(id)})

How can I retrieve data using PyMongo?

1 Answers1