MongoDB for Developers with Python Transcripts
Chapter: Mapping classes to MongoDB with the ODM MongoEngine
Lecture: Registering connections in mongoengine
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Now let's begin by setting up MongoEngine,
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there's a few start of the app kind of configuration things we need to do
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in order to use MongoEngine, and then we just use
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the classes and types throughout the app.
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So what I want to do is I'm going to create a folder here
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let's call it NoSQL, so we're going to put
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a number of MongoEngine related things in here
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and I don't want to call it MongoEngine because then it will conflict with the name
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so, lacking creativity I'm calling it this,
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now there's a couple of things we need to do
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we need to set up the connections and then we need to define the classes,
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this first part we're just going to set up the connection.
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I'll create a module called Mongo setup, ok
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so down here, let's define a function
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called global init, we are going to call this function from outside.
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Now, in real life later as we talk to like sort of the production stuff
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we're going to want to pass in like the user name, the password, the server name
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all sorts of stuff that you know maybe in a real app comes from
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like a config file or the environment in a production server, something like that,
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but for now we're just going to put this in here.
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So to get started, we have to import MongoEngine,
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we don't need PyMongo but MongoEngine we need.
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And then down here, it's really simple what we need to do,
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we're going to register a connection,
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so we're not actually going to open the connection here,
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this doesn't talk to the database, but it basically says
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look if you have a class that maps
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to a particular type or named part of our application
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use this database connection to do the backend work.
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So we're going to come down and say Mongoengine.register connection
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and see it has alias name and then other,
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and what comes with the other, the .... there
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is like the connection string information
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like server name, port name, host name, use ssl, replica set, all that kind of stuff.
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Okay, so we're going to say, make it really explicit here
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we're going to say alias, I was going to call this core
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and I'll you what that means in a minute, so let's call this demo_dealership.
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Now normally, I would probably just use dealership
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but I already have that for something else
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in a previous example, I kind of want to keep it around
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so we're going to say demo_dealership,
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there we go, and that's all we're going to need to do.
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So the idea is here, we could have multiple things like analytics
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it could be here, and this could be visits or whatever,
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it could be mapping to another database assuming I spelled analytics correctly ;
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so in our classes, we can say this class belongs in the core database,
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whatever that happens to be configured as,
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this one over here, happens to belong in the analytics database
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and so I find it's really valuable if you've got like some core data
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that are required to make your app run,
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and then like huge amounts of extra analytical type data,
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that if you lost, it's like oh well I'd rather have that data
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but if for some reason I want to back up
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let's say you've got 5 GB of analytic data and a 100 MB of core data,
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you could run backups on the core server
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much more frequently than the analytics one
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and by partitioning them to different databases or even different servers
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you can do a lot of cool tricks like that.
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Alright, all that said, we're not doing that,
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we're just going to have one database that we're calling core
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so we're going to register this connection
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and when we get to defining the classes
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you'll see a place where we refer to the core connection,
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that's what we've configured here, and it's going to default local host
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default port everything like that.
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Again, when we get to the using MongoDB in production,
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we're going to talk about how to pass all the extra information you need
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to use this for real, on another server, on another port,
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with authentication, everything,
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but for now, this is what we're going to do to set it up.
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So let's go ahead and get started, using this,
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let's go down here, and we've got our print header,
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let's go ahead and do a config Mongo,
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so it's easy enough to import, let's go up here at the top, our module,
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so we'll just call it Mongo setup like this, and I'll just say global init
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do a little pep8 formatting, and we're good to go,
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and it thinks this is misspelled, no, just short alias for MongoDB.
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Okay let's just run it to make sure everything is working,
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alright, there is no real way to test it yet, but in a moment, we will,
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so far everything worked, we configured our MongoDB connection,
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next up, it's to actually think about modelling these cars
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and owners and service, and all those kinds of things.
