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Interact with MongoDB using Mongoose ODM
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Overview

This node enables interaction with MongoDB databases using the Mongoose Object Data Modeling (ODM) library. It supports a variety of operations such as finding one or multiple documents, creating, updating, deleting documents, counting documents, and running aggregation pipelines on specified collections within a MongoDB database.

The "Find One" operation specifically retrieves a single document from a collection that matches a given query filter. This is useful when you want to fetch a unique record or the first matching record based on certain criteria.

Common scenarios:

  • Retrieving user details by a unique identifier or email.
  • Fetching configuration or settings stored in a MongoDB collection.
  • Querying for a single document to check existence or get detailed information.

Practical example:
You have a users collection and want to find a user whose name is "John" and age is at least 18. You can specify a query like:

{
  "name": "John",
  "age": { "$gte": 18 }
}

and retrieve only selected fields such as _id, name, and email.

Properties

Name Meaning
Database The name of the MongoDB database to connect to. Leave empty to use the default database from credentials.
Collection The name of the collection to operate on (required).
Query MongoDB query object in JSON format to filter documents. Leave empty {} for no filter.
Schema Definition JSON definition of the Mongoose schema for the collection. Defines field types and structure (required).
Select Fields JSON string specifying which fields to include or exclude in the result. Leave empty to select all fields. Example: {"_id": 1, "name": 1}
Include Query Info Boolean flag indicating whether to include raw MongoDB query information in the response.
Options Additional options including:
- Limit Maximum number of results to return (not applicable for "findOne").
- Skip Number of documents to skip (not applicable for "findOne").
- Sort JSON object defining sort order (e.g., {"name": 1, "age": -1}) (not applicable for "findOne").
- Select String listing fields to include/exclude (e.g., "name email -_id") (not applicable for "findOne").
- Query Timeout (Ms) Maximum time in milliseconds to allow the query to run (1,000 to 300,000 ms).
- Debug Mode Enables Mongoose debug mode to log all MongoDB queries in the console.

Output

The output is an array of items where each item contains a json property with the following structure for the "Find One" operation:

  • The main content is the found document represented as a plain JSON object with the fields selected according to the input parameters.
  • If no document matches the query, the output will be null.
  • If "Include Query Info" is enabled, the output JSON also includes metadata about the executed query and options used.

Example output JSON:

{
  "data": {
    "_id": "60d5ec49f8d2c4567a123456",
    "name": "John",
    "email": "john@example.com",
    "age": 25
  },
  "query": {
    "name": "John",
    "age": { "$gte": 18 }
  },
  "options": {
    "limit": 1000,
    "skip": 0,
    "sort": {},
    "selectFields": { "_id": 1, "name": 1, "email": 1 }
  },
  "operation": "findOne"
}

No binary data output is produced by this operation.

Dependencies

  • Requires a MongoDB instance accessible via a connection string.
  • Uses Mongoose ODM library for schema definition and querying.
  • Requires an API key credential or similar authentication token configured in n8n to connect to MongoDB.
  • Supports multi-database connections by specifying the database name or using the default from credentials.

Troubleshooting

  • Connection errors:
    Errors like "MongoDB connection error", "connection refused", or "host not found" indicate issues with the connection string, network, or MongoDB server availability. Verify the connection string, hostname/IP, port, and ensure MongoDB is running and reachable.

  • Authentication failures:
    Messages mentioning "authentication failed" suggest incorrect username, password, or authentication database settings. Double-check credentials and authentication parameters.

  • Query parsing errors:
    Invalid JSON in the "Query" or "Select Fields" properties will cause errors. Ensure these inputs are valid JSON strings.

  • Limit exceeded:
    The node enforces a maximum limit of 10,000 documents for safety. Setting a higher limit will throw an error.

  • Large result sets warning:
    When retrieving many documents (more than 5,000), a console warning suggests adding indexes or refining filters to improve performance.

  • Schema mismatch:
    Incorrect schema definitions may cause unexpected behavior. Make sure the schema JSON correctly reflects the collection's document structure.

Links and References

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