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Defining a Mongo Schema with Mongoose
4:44In this video, learn how to create a schema for MongoDB using Mongoose. You'll learn how to create a document schema with keys and additional properties to control the type of data Mongoose will store in MongoDB.
To add data from the registration
form to Mongo DB,
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we'll need to tell
Mongoose about that data.
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To do that we create what's
called a model or schema,
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which gives Mongoose information about
the document we want to store in Mongo.
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Remember, Mongo is a document database,
so each user record we
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add to the database is called a document,
and is stored as a JSON like object.
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A model describes what that document
should contain including the names we'll
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use to identify each piece of information
like name, e-mail or password, and
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the type of information we want to
store like a string, number or date.
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Let's look at the registration form.
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There are five fields for name,
email address, favorite book, one for
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the password, and a second one
to confirm that user's password.
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For each user we want to store four pieces
of information in Mongo, the name, email,
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favorite book, and password.
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That's basically the schema
we need to create.
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I'll open the project in my text editor
and add a folder to store the model in.
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I'll call it models.
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At this point we're only
interested in a single schema,
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to capture the user
registration information.
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But as this app is built out,
you could add more schemas for
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storing information about books,
forum discussions and so on.
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I'll create a file in here named user.js.
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To start, I need to require
Mongoose at the top of the file.
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This loads the module and
stores it in a variable named mongoose.
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To create a schema, we must create
a new mongoose schema object.
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I'll store it in a variable
named user schema.
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You pass an object to the schema method.
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The object is composed of keys and values.
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The key is the name for the data, in
other words, the name of the form field.
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The value is the type of data
you want to store in it.
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For example,
this code defines a simple schema
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composed of one piece of data named email,
which contains a string.
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Mongoose and Mongo have other data types,
like number, date, as well.
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Notice that the s in
String is capitalized.
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We could write the same code for
our other form fields.
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Name, password etc.
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However, this isn't quite good enough for
our app.
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When the user signs up with our site, we
want to make sure we get all of the data.
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Name, email, password and favorite book.
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None of that data is optional.
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Fortunately, Mongoose lets you make
any number of fields required.
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So that if the user tries to
add a record without that info,
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Mongoose refuses to create a new document
and sends back an error message.
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To add more requirements to your data,
you must assign another object to the key,
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with metadata in it.
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For example, I'll replace string
here with another object.
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This object has a few keys, type, unique,
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required, and trim.
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Type is the type of data, a string.
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The unique attribute
ensures that the provided
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email address does not already
exist in the database.
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We wanna make sure that no two users can
create an account with the same email
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address because the email
address identifies
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a unique user when
logging into the website.
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I've also added the required attribute,
and set that to true as well.
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So that Mongo D.B.
enforces the presence of the email field.
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Also for text fields that the user types
into, we can add a trim attribute and
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set it to true.
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Trim removes any whitespace before or
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after the text that might have been
typed into the form accidentally.
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I'll add similar information for
the other fields.
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One for the name field,
which is also a string.
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It's also required, and
we'll also trim it.
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One for the favorite book.
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It's a string.
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It's required, and we'll trim it, as well.
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You don't need to type all of this
yourself if you don't want to.
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You'll find the code listed
in the teacher's notes.
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And finally, I'll add the password.
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Again, it's a string and it's certainly
required, but I'm not going to use trim
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here because maybe the user will
add a space at the beginning or
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end to make their
password harder to crack.
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Finally, to use the schema in our
application, we need to export it.
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Here, I'm creating a new
variable called User and
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I'm using Mongoose's model method.
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And this creates our schema.
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Now to use this model, we'll need to
tell our application about it, and
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we need to export it here.
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So in the next video,
we'll hook all of the parts together so
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that the app can add data
to our Mongo database.
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