71 lines
2 KiB
Markdown
71 lines
2 KiB
Markdown
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---
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categories:
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- Databases
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tags: [mongo_db, node_js, mongoose]
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---
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# Creating a schema and model
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## Schema
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In order start adding [collections and documents](/Databases/MongoDB/Introduction.md) to our database, we use Mongoose's **schema** structure. (This is specific to Mongoose and is not a structure that is a part of Mongo in general.)
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We use a schema to define the shape of documents in a MongoDB collection. To do this we instantiate an instance of the Mongoose `Schema` class and set our properties:
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### Creating a schema
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```js
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const courseSchema = new mongoose.Schema({
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name: { type: String, required: true, minlength: 5, maxlength: 255 },
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author: String,
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tags: [String],
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data: { type: Date, default: Date.now }, // if unspecified, entry will default to current date
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isPublished: Boolean,
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});
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```
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> This is similar to declaring a type or interface in TypeScript
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// TODO: Add printout of what the rejection will look like in the console.
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#### Available data types
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The following data types are available:
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- `String`
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- `Number`
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- `Boolean`
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- `Array`
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- `Date`
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- `Buffer`
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- `ObjectID` (for UUIDs)
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> Note that we set our validation criteria as the second property for each schema value. There is more info info on validation in a [separate entry](/Databases/MongoDB/Validating_Mongoose_schemas.md);
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## Models
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Once we have established our schema we can then create a **model** of it. A model is basically a class representation of the interface we define in the schema:
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```js
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const Course = mongoose.model("Course", courseSchema);
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```
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Now we can start adding specific courses as documents to our collection. We do this by referring to the model, i.e.
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```js
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const course = new Course({
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name: "Node.js Course",
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author: "Ozzy Osbourne",
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tags: ["node", "backend"],
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isPublished: true,
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});
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```
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## Outcome
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Having created a database, connected to it with Mongoose, and created a model we will see our collection reflected in Compass:
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