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Cheat Sheet: Common Methods and APIs

Practical mongosh reference for database, collection, CRUD, cursor, index, aggregation, and diagnostic methods.

db

Reference type:Cheat sheetFormat:Syntax + example + use case

Reference group: Database and collection discovery

What it does

The database object selected in the current mongosh session.

Syntax

db

Use case

Inspect the active database and call its collection methods.

db: practical example

db

💡 Explanation The database object selected in the current mongosh session. When to use it Inspect the active database and call its collection methods.

Key Takeaways

The database object selected in the current mongosh session.
Typical use: Inspect the active database and call its collection methods.

db.getName()

Reference type:Cheat sheetFormat:Syntax + example + use case

Reference group: Database and collection discovery

What it does

Returns the current database name.

Syntax

db.getName()

Use case

Check that a script targets the intended database.

db.getName(): practical example

db.getName()

💡 Explanation Returns the current database name. When to use it Check that a script targets the intended database.

Key Takeaways

Returns the current database name.
Typical use: Check that a script targets the intended database.

show dbs

Reference type:Cheat sheetFormat:Syntax + example + use case

Reference group: Database and collection discovery

What it does

mongosh helper listing databases visible to the current user.

Syntax

show dbs

Use case

Discover available development databases; empty databases may not appear.

show dbs: practical example

show dbs

💡 Explanation mongosh helper listing databases visible to the current user. When to use it Discover available development databases; empty databases may not appear.

Key Takeaways

mongosh helper listing databases visible to the current user.
Typical use: Discover available development databases; empty databases may not appear.

show collections

Reference type:Cheat sheetFormat:Syntax + example + use case

Reference group: Database and collection discovery

What it does

mongosh helper listing collections in the current database.

Syntax

show collections

Use case

Inspect collection names while debugging.

show collections: practical example

show collections

💡 Explanation mongosh helper listing collections in the current database. When to use it Inspect collection names while debugging.

Key Takeaways

mongosh helper listing collections in the current database.
Typical use: Inspect collection names while debugging.

db.getCollectionNames()

Reference type:Cheat sheetFormat:Syntax + example + use case

Reference group: Database and collection discovery

What it does

Returns collection names as an array.

Syntax

db.getCollectionNames()

Use case

Inspect a database programmatically.

db.getCollectionNames(): practical example

db.getCollectionNames()

💡 Explanation Returns collection names as an array. When to use it Inspect a database programmatically.

Key Takeaways

Returns collection names as an array.
Typical use: Inspect a database programmatically.

db.getCollection()

Reference type:Cheat sheetFormat:Syntax + example + use case

Reference group: Database and collection discovery

What it does

Returns a collection object by name, including names awkward to access with dot notation.

Syntax

db.getCollection(name)

Use case

Access dynamically named collections.

db.getCollection(): practical example

db.getCollection("user-events").findOne()

💡 Explanation Returns a collection object by name, including names awkward to access with dot notation. When to use it Access dynamically named collections.

Key Takeaways

Returns a collection object by name, including names awkward to access with dot notation.
Typical use: Access dynamically named collections.

db.createCollection()

Reference type:Cheat sheetFormat:Syntax + example + use case

Reference group: Database and collection discovery

What it does

Explicitly creates a collection with options such as validation or capped behavior.

Syntax

db.createCollection(name, options)

Use case

Create a collection with specific settings.

db.createCollection(): practical example

db.createCollection("events", { capped: true, size: 1048576 })

💡 Explanation Explicitly creates a collection with options such as validation or capped behavior. When to use it Create a collection with specific settings.

Key Takeaways

Explicitly creates a collection with options such as validation or capped behavior.
Typical use: Create a collection with specific settings.

db.dropDatabase()

Reference type:Cheat sheetFormat:Syntax + example + use case

Reference group: Database and collection discovery

What it does

Drops the current database.

Syntax

db.dropDatabase()

Use case

Reset a disposable test database.

Important notes

Destructive: verify database selection and privileges first.

db.dropDatabase(): practical example

db.dropDatabase()

💡 Explanation Drops the current database. When to use it Reset a disposable test database. Caution Destructive: verify database selection and privileges first.

Key Takeaways

Drops the current database.
Typical use: Reset a disposable test database.

insertOne()

Reference type:Cheat sheetFormat:Syntax + example + use case

Reference group: Collection CRUD methods

What it does

Inserts one document and returns its inserted identifier.

Syntax

db.collection.insertOne(document)

Use case

Create a record and retain insertedId.

insertOne(): practical example

db.products.insertOne({ sku: "KB-1", price: 1999 })

💡 Explanation Inserts one document and returns its inserted identifier. When to use it Create a record and retain insertedId.

Key Takeaways

Inserts one document and returns its inserted identifier.
Typical use: Create a record and retain insertedId.

insertMany()

Reference type:Cheat sheetFormat:Syntax + example + use case

Reference group: Collection CRUD methods

What it does

Inserts multiple documents. Ordered writes stop at the first error by default; unordered writes may continue.

Syntax

db.collection.insertMany(documents, { ordered })

Use case

Seed or import batches.

Important notes

Unordered operations can partially succeed; inspect write errors.

insertMany(): practical example

db.products.insertMany([{sku:"KB-2"},{sku:"KB-3"}], { ordered: false })

💡 Explanation Inserts multiple documents. Ordered writes stop at the first error by default; unordered writes may continue. When to use it Seed or import batches. Caution Unordered operations can partially succeed; inspect write errors.

Key Takeaways

Inserts multiple documents. Ordered writes stop at the first error by default; unordered writes may continue.
Typical use: Seed or import batches.

db

db.getName()

show dbs

show collections

db.getCollectionNames()

db.getCollection()

db.createCollection()

db.dropDatabase()

insertOne()

insertMany()

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