This picks up from the last post, which you can find here:
http://dansrandombits.blogspot.com/2012/11/python-and-flask-and-mongodb-part-1a.html
This section concerns itself with dealing with MongoDB, then accessing data in Mongo through Flask to display to a web client.
Install Mongo, create database with a collection of three records
First, we have to get Mongo installed with some simple data. Download MongoDB from http://www.mongodb.org, and use version 2.2 or higher.
Unzip, and move the contents to a new folder--on my Mac, I put the latest MongoDB in my user home directory in its own folder under ~/bin/mongodb, then I symlink it to ~/bin/mongodb/current, and create a data directory as well to hold the Mongo databases. These command lines do the trick after Mongo's downloaded.
mkdir ~/bin/mongodb
tar -zxvf ~/Downloads/mongodb-osx-x86_64-2.2.1.tgz -C ~/bin/mongodb
ln -s mongodb-osx-x86_64-2.2.1/ current
mkdir ~/bin/mongodb/data
Now launch Mongo:
cd ~/bin/mongodb/
./current/bin/mongod -dbpath ./data/db
Add records to Mongo
Open another terminal window, and open the mongo client. We'll create a database named test, and insert three records into a collection called "fruits"
cd ~/bin/mongodb
./bin/mongo
This gets you a mongo prompt.
show dbs
use test
db.fruits.insert({name: "apple"})
db.fruits.findOne()
db.fruits.insert({name: "orange"})
db.fruits.insert({name: "banana"})
db.fruits.distinct("name")
db.fruits.distinct("name").sort()
Now let's add another field called displayOrder:
db.fruits.update({name: "apple"}, {$set: {displayOrder: 1}})
db.fruits.update({name: "banana"}, {$set: {displayOrder: 2}})
db.fruits.update({name: "orange"}, {$set: {displayOrder: 3}})
Let's find these:
db.fruits.find()
{ "_id" : ObjectId("502f1f4098075d85dc674fb5"), "displayOrder" : 1, "name" : "apple" }
{ "_id" : ObjectId("502f284f98075d85dc674fb7"), "displayOrder" : 2, "name" : "banana" }
{ "_id" : ObjectId("502f284b98075d85dc674fb6"), "displayOrder" : 3, "name" : "orange" }
Connect Flask to MongoDB
This is the last part of this document -- and to do this, we'll add what Flask calls a route. It'll be our first route, so we'll just call it mongo1.
First, install the pymongo driver. There's no ORM or anything here; Flask will connect directly to MongoDB.
sudo pip install pymongo
Next, update that hello.py file. Insert this code below the line that says return "Hello World!", and before "if __name__ = 'main'"
from pymongo import Connection
conn = Connection('127.0.0.1', 27017)
@app.route("/mongo1")
def find():
dbTest = conn['test']
dbDocs = []
for fruit in dbTest['fruits'].find():
dbDocs.append(fruit)
return str(dbDocs)
Stop Flask on the command line if it's still running with a control-C, then relaunch it with python hello.py. (If you're using PyCharm select the hello.py file in the left-hand Project window, right click, and choose Debug.)
In the mongod window you'll see something like this that lets you know you've connected to Mongo:
Fri Aug 17 13:13:13 [initandlisten] connection accepted from 127.0.0.1:53824 #2 (2 connections now open)
Now in a web browser visit that route at http://127.0.0.1:5000/mongo1
You'll see those three records returned in JSON format, which is effectively how both Python and MongoDB store their data--effectively means it's not quite true, but close enough.
What's happening here?
First of all, the route /mongo1 is bound to the function find(), which makes a connection to the Mongo database ['test'].
dbDocs is declared as an empty list, and then a find request is made to the collection 'fruits'. The for loop iterates with the results from the find(), and builds up a Python list named dbDocs. Finally, dbDocs is converted into a string, and returned to the user's web browser, where it appears as unformatted JSON.
That's it for now, but it does show you how you can quickly build a simple web service using Flask and Mongo.
Additional directions to go from here would be to use templates for rendering, getting a bit of styling in place, and isolating the Flask application into its own Python environment.
