00:00 The first thing that we need to do
00:01 to start working with MongoEngine is
00:03 tell MongoEngine how to speak to MongoDB.
00:06 Let's go back to our Snakebnb app we've been working on.
00:09 And we're going to go in here to this data section.
00:12 we're going to create a new file,
00:14 a new Python file called mongo_setup.
00:16 So in here, we're going to write a simple method
00:19 that we can call from other places,
00:20 and as you'll see in the slides that we look at later,
00:24 for real applications that use proper connections,
00:28 encryption, accounts, things like that,
00:29 this can be a little more complicated,
00:31 but it's going to start out pretty simple,
00:32 so we'll say, "global_init()" and in here,
00:35 we just want to call one function,
00:37 so we're going to have to have MongoEngine here,
00:40 so we'll import MongoEngine,
00:41 and we'll just say, "mongoengine.register_connection()"
00:44 and the first thing that we pass is an alias,
00:47 so I'll be real explicit and say, "alias='core' "
00:50 Now what is this alias thing about?
00:51 We can have multiple connections to even multiple databases,
00:55 or even multiple database servers registered here.
00:58 We could have like a core data and
01:01 say analytics for just analytics that goes to a
01:03 separate database that maybe has tons more data
01:06 because it's page views, and actions, and so on.
01:08 But we might keep that separate, so we can back it up
01:10 on a separate schedule, something like that.
01:12 Then, we need to set the name of the database,
01:15 and we'll set that to Snakebnb.
01:17 Do a quick format here, and it's all good to go.
01:20 Like I said, this gets more interesting in real connections.
01:23 We're going to need to call this to talk to MongoDB,
01:27 so let's go over to our little program,
01:28 and you saw up here at the top, there was this to do,
01:31 setup MongoEngine global values,
01:32 and that was basically what we were doing there,
01:35 so we need to come over here and say,
01:36 you need to go to "data.mongo_setup"
01:39 We'll just call it "mongo_setup"
01:42 And this should be pretty simple,
01:43 mongo_setup.global_init()
01:45 Now we just need to make sure we call this once
01:47 in our application and we need to do this
01:49 before we actually interact with anything else,
01:52 so let's go and apply these settings
01:54 over to our entities as well, so we'll look at snakes first.
01:59 Now this model is going to be mapped
02:01 into one or more of those databases.
02:04 Well, one among many potential databases,
02:06 so the way that we can tell it how to work,
02:09 MongoEngine will use a property we can add to it.
02:12 We can say "meta = " and we give it a dictionary,
02:14 and we can say " 'db_alias' "
02:17 and we'll say " 'core', " here, okay?
02:18 While we're at it let's say, " 'collection': 'snakes' "
02:22 So even though we called it capital S snake,
02:25 the thing in the database where these records,
02:27 these documents are stored will be called
02:29 snakes, plural, lowercase, and here we can tell it
02:31 if this goes into the core database,
02:33 unlike maybe the analytics one, or something like,
02:36 all right, we're only going to have one in here,
02:37 but for our example, you want to have this here,
02:39 in case you want to add more later.
02:41 All right, I'll go ahead and add the rest of these
02:43 to owners and cages, but not bookings,
02:46 because bookings is going to be nested inside here, all right,
02:49 so we don't need to tell that how it gets stored,
02:51 'cause it's stored alongside cage,
02:54 triple set of cages, and no surprise, owners.
02:57 All right, so those are our three top-level entities
03:00 that map to our three top-level collections in MongoDB.
03:02 Now, we've registered the connection
03:04 by using our Mongo Setup Global,
03:06 which should we just call a regular connection.
03:08 Like I said, this shuouldn't get
03:09 way more complicated in reality, and then,
03:11 we just go and we set this meta to use the core connection
03:14 as well as naming the actual table
03:16 or collection it's going to go to.