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So what is mongoose? Mongoose is an ODM, an object document mapping library

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and that's really similar to sequelize which was an ORM, an object relational mapping library

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and the difference of course just is that mongodb is not a relational database,

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it's a document database,

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it thinks in documents and hence we have an ODM here.

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So the idea stays the same though, we have some data, some entity in our application,

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let's say a user and we want to save that to a collection, we want to map our javascript object to a

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document in a collection that could look something like this

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and of course we can write the query for that on our own,

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that is exactly what we did in the last module but it would be a bit easier if we could just focus on

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our objects, on our data and see how it should look like and then work with it and this is not even

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the final syntax you see here,

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we can use mongoose a bit differently than you see it here but even that would be a bit more concise.

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So just as sequelize,

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mongoose tries to allow us to define models with which we then work and where all the queries are done

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behind the scenes which of course does not mean that we can't influence and that we can't change some

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things.

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The core concepts are that we work with schemas and models where we define how our data should look like

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and then we have so-called instances where we instantiate our models,

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so where we create real javascript objects we can work with that are based on our blueprints

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and once we get that setup, we can run queries and there we again use our objects, we use our models

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and we can then query the database

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but through mongoose with various helpers we get, some syntactical sugar and so on.

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So that's the idea behind mongoose, really similar to what sequelize did for SQL

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and therefore with that, let's dive in, let's add it to our project and let's see how we can use it there.