Building Data-Driven Web Apps with Pyramid and SQLAlchemy Transcripts
Chapter: MongoDB edition
Lecture: Connecting to MongoDB

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0:00 Now, let's get started with MongoDB.
0:03 We're going to do something very similar
0:04 to what we did with our relational database
0:06 and we're not going to write in raw SQL.
0:09 When we did our relational stuff
0:10 we worked with SQLAlchemy and classes.
0:13 Same thing here, we're not going to write
0:15 in the lowest level query syntax
0:17 and just exchange dictionaries with MongoDB
0:20 which is the lowest level, by the way.
0:22 We're going to use something that is sort of a parallel
0:24 or the equivalent of SQLAlchemy
0:26 something called MongoEngine.
0:31 So, let's start by adding that as a requirement here.
0:33 Notice now, we're running 3.6.
0:35 You may not have noticed before we were running 3.7.
0:38 At the time of this recording
0:41 3.7 just came out and MongoEngine does not support it.
0:44 There's some incompatibility.
0:46 They have a fix in GitHub.
0:47 It's not yet published to PyPI.
0:52 I'm going to go ahead and install that.
0:55 That's good, and apparently, I have an old pip.
0:57 So, this is the old pip
0:59 in my new virtual environment, right?
1:04 We have MongoEngine satisfied.
1:05 Great, that was super easy.
1:06 That was the same as putting SQLAlchemy here.
1:09 The other thing we did with SQLAlchemy
1:10 remember, we created this DB session
1:14 with the connection string
1:16 and then we created the engine with the connection string
1:18 and then we created the session factory from that
1:22 and all those things?
1:24 Well, we're going to do all of this
1:25 but we're going to do it a lot simpler for MongoDB
1:27 because it is simpler.
1:28 Now, I may well just put it into data.
1:31 If I was doing a fresh, from scratch only MongoDB site here
1:36 I would just make a data folder
1:37 and put stuff in there that is MongoDB-related
1:39 not SQLAlchemy-related.
1:41 But one of the steps I want to do for you
1:43 in this chapter is to convert, to import
1:46 all of our data from a relational database into MongoDB.
1:50 For that to work easily
1:51 we're going to still want these to be around
1:53 because we need them to do that transformation.
1:56 So, I'm going to create a second folder
1:57 and we'll call this nosql.
1:59 But really, data would be appropriate
2:01 if it weren't already taken.
2:02 So just like we have this DBSession.factory
2:05 I'm going to create a new file called mongo_setup.
2:09 And we'll define a function, just like we said before
2:12 global_init, and it'll have a db_name, which is str
2:17 and it's going to do some really, really simple stuff
2:20 for a simple case.
2:22 And then, I'll show you a slightly more advanced version
2:24 that you will have to use in production
2:25 with all the various settings you have to pass.
2:28 So the simple version is we're going to import mongoengine.
2:31 I'm going to come down here
2:32 and say mongoengine.register_connection.
2:35 I'm going to pass an alias.
2:37 So this is like the shared database connection name.
2:40 We'll reference this later.
2:42 And then the name, it's going to be the name of the DB
2:45 so we'll say pypi_nosql.
2:48 We'll just call it that.
2:49 That seems decent.
2:51 And that's all we have to set.
2:52 The host, the port, all those things
2:53 are going to default across.
2:56 Though I guess if we're passing the name
2:58 let's say DB name here
3:01 we can even just default it.
3:02 So we call it like this or we can override it.
3:04 Okay, great, this is the simple version
3:07 and this is all we're going to need
3:08 but let me just drop the real, quote, real version
3:12 that you'll need for a real complicated remote server
3:17 with authentication and encryption and all that.
3:19 So instead of this nice simple version
3:20 which is our localhost version
3:22 this'll totally work
3:23 we're going to have a slightly more complicated version
3:25 with our default name there.
3:27 So here's the version what you just saw
3:31 but here's the version that we're going to use
3:34 for actually connecting to MongoDB in production with SSL
3:37 and authentication, and usernames, and passwords
3:40 and remote servers, and all that stuff.
3:41 Okay, so this is what we need to get connected.
3:44 I'm going to just put that away.
3:47 Let's go to our init_db.
3:49 We're going to not do that stuff anymore, are we?
3:51 We're now going to go mongo_setup
3:54 and we got to import that of course.
3:57 I think that that needs to be package
4:00 sub-package so let's do this.
4:06 That was it.
4:07 So now we're going to import that
4:08 and we'll say global_init
4:09 and we won't pass anything
4:11 just going to do the defaults
4:12 no user, no password, localhost
4:14 everything, just like that.
4:16 And this is it.
4:17 This is enough for us to talk to MongoDB
4:19 and it also will do all that create table equivalent stuff.
4:23 Okay, so this step is going to get us connected.