Introduction

Reasons behind this

The reasons behind this project are:

• Many times I need to run test queries on a MongoDB server, eg. to see the status of the stored data, often with some aggregations / “GROUP BY”. And I hate having to write JSON inline in the CLI, with all the (un)readability problems..

• In any case, I find that JSON queries tend to become unreadable quite soon, even in program code.

  And I hate writing things like: {'$and': [cond1, cond2, ...]}.

  And I think that polish notation tends to become hard to follow quickly: compare, for example, (5 - 6) * 7 with * - 5 6 7 (polish notation), (* (- 5 6) 7) (lisp) or, worse of them all, the mongodb way: {'$multiply': [{'$subtract': [5, 6]}, 7]}...

Reasons NOT behind this

The goal of this project is not to use MongoDB as a drop-in, web-scale replacement for MySQL, to make your cats blog run the speed of light!

Example usage

Everyone likes examples! All right then..

First, let’s connect to our MongoDB server:

from mongosql import MongoSqlClient
conn = MongoSqlClient('mongodb://localhost:27017')

Then, we’ll populate the database a bit, using the standard MongoDB way (MongoSqlClient extends pymongo.MongoClient):

db = conn.my_test_db
for item in 'World Spam Eggs Bacon Spam Spam Spam'.split():
    db.mycollection.save({'hello': 'Hello, {name}!'.format(name=item)})

Ok, it’s time for our first SQL-based query to MongoDB!

result = db.sql('SELECT * FROM mycollection WHERE hello == "Hello, Spam!"')

If you inspect the contents of result, you’ll see it worked!

for item in result:
    print(item)

{u'_id': ObjectId('....01'), u'hello': u'Hello, Spam'}
{u'_id': ObjectId('....04'), u'hello': u'Hello, Spam'}
{u'_id': ObjectId('....05'), u'hello': u'Hello, Spam'}
{u'_id': ObjectId('....06'), u'hello': u'Hello, Spam'}

Now, experiment with more complex queries. Some examples:

• ... WHERE field == "value" AND other == "value2"
• ... WHERE field in ['foo', 'bar']
• ... WHERE price < 10 OR price > 100

(Quite likely, you’ll experience issues at a certain point. Please feel free to report issues to help speeding up the development!)

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