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Use Snippets in the Console

Warning

This feature is experimental. MongoDB does not provide support for Snippets. This feature may be changed or removed at any time without prior notice.

Bugs are not expected, however should you encounter one, please open an issue in the GitHub repository for this project.

This page is an overview of working with snippets in the mongosh console.

Install Snippet Packages

You must install a snippet package before you use it. Once a snippet package has been installed, it is loaded each time mongosh starts.

If you know the name of the snippet you want to install, enter:

snippet install <name>

Otherwise, search the repository to get a list of available snippets.

snippet search

Once the snippet is installed, enter y to load it.

 Running install...
 Installed new snippets analyze-schema. Do you want to load them now? [Y/n]: y
 Finished installing snippets: analyze-schema

Note

If this is the first time you have used snippets you may see a warning like the following:

This operation requires downloading a recent release of npm. Do
you want to proceed? [Y/n]:

You must install npm to use snippets.

Run a Snippet

Before running a new snippet, run snippet help <SNIPPET NAME> to learn more about the snippet's functionality.

For example, snippet help analyze-schema indicates that you can use the the analyze-schema by passing it a collection name.

testDB> snippet help analyze-schema
 # analyze-schema
 Analyze the schema of a collection or a cursor.
```js
> schema(db.coll);
┌─────────┬───────┬───────────┬────────────┐
│ (index) │   0   │     1     │     2      │
├─────────┼───────┼───────────┼────────────┤
│    0    │ '_id' │ '100.0 %' │ 'ObjectID' │
│    1    │ 'a  ' │ '50.0 %'  │  'Number'  │
│    2    │ 'a  ' │ '50.0 %'  │  'String'  │
└─────────┴───────┴───────────┴────────────┘

Once you know how to call a snippet, you can use it as in the following example.

Consider the reservations collection:

db.reservations.insertMany( [
   {"_id": 1001, "roomNum": 1, "reserved": true },
   {"_id": 1002, "roomNum": 2, "reserved": true },
   {"_id": 1003, "roomNum": 3, "reserved": "false" },
   {"_id": 1004, "roomNum": 4, "reserved": true },
] )

To analyze the collection, install the analyze-schema snippet if it is not already present, pass in the collection name to run it.

snippet install analyze-schema
schema(db.reservations)

The document with "_id": 3 was misentered as a string. The analysis shows that the reserved field has string elements in addition to the expected booleans.

┌─────────┬────────────┬───────────┬───────────┐
│ (index) │     0      │     1     │     2     │
├─────────┼────────────┼───────────┼───────────┤
│    0    │ '_id     ' │ '100.0 %' │ 'Number'  │
│    1    │ 'reserved' │ '75.0 %'  │ 'Boolean' │
│    2    │ 'reserved' │ '25.0 %'  │ 'String'  │
│    3    │ 'roomNum ' │ '100.0 %' │ 'Number'  │
└─────────┴────────────┴───────────┴───────────┘

Uninstall Snippets

Use the snippet uninstall command to remove a snippet. If you are unsure of the name, the snippet ls command lists all installed snippets.

This code uninstalls the analyze-schema snippet.

snippet uninstall analyze-schema

Find Available Snippet Packages

The snippet ls command returns a list of locally installed snippets along with some version and source information.

snippets@ /root/.mongodb/mongosh/snippets
├── mongosh:PRIVATE..DecryptCards@1.0.5
├── mongosh:analyze-schema@1.0.5
└── npm@7.23.0

To see the snippets that are available in the registry, first refresh the local metadata cache and then search.

snippet refresh
snippet search

snippet search lists available snippets, their version, and gives a brief description.

This instance has a second, private registry configured. Since the private registry was listed first, those snippets precede the MongoDB snippets in the list of available snippets.

┌─────────┬─────────────────────────────────┬─────────┬────────────────────────────────────────────────────────────────┐
│ (index) │              name               │ version │                          description                           │
├─────────┼─────────────────────────────────┼─────────┼────────────────────────────────────────────────────────────────┤
│    0    │     'PRIVATE..DecryptCards'     │ '1.0.5' │                 'Decrypt credit card numbers'                  │
│    1    │ 'PRIVATE..updateAuthentication' │ '1.0.2' │             'Update user pwds and authentication'              │
│    2    │          'resumetoken'          │ '1.0.2' │                 'Resume token decoder script'                  │
│    3    │          'mongocompat'          │ '1.0.7' │            'mongo compatibility script for mongosh'            │
│    4    │         'spawn-mongod'          │ '1.0.1' │                'Spin up a local mongod process'                │
│    5    │        'mock-collection'        │ '1.0.2' │ 'mockCollection([{ a: 1 }, { a: 2 }]).find({ a: { $gt: 2 } })' │
│    6    │        'analyze-schema'         │ '1.0.5' │                       'schema(db.coll)'                        │
└─────────┴─────────────────────────────────┴─────────┴────────────────────────────────────────────────────────────────┘

Get Repository Information

Display the homepage and URL for each snippet repository:

snippet info

The output lists each repository.

Snippet repository URL:      https://compass.mongodb.com/mongosh/snippets-index.bson.br
  -->  Homepage:             https://github.com/mongodb-labs/mongosh-snippets

Get Help for a Snippet

Each snippet is unique and has its own interface. The best way to find information about how a particular snippet works is to view its README file by running snippet help:

snippet help mongocompat

This command displays the README file for the mongocompat snippet in the mongosh console.

# mongocompat
Provide `mongo` legacy shell compatibility APIs.
```js
> Array.sum([1, 2, 3])
6
> tojsononeline({a:1,b:2,c:3})
{  "a" : 1,  "b" : 2,  "c" : 3 }
```

When you create your own your own snippet packages, be sure to include a README.md file that provides useful help.

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