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The MongoDB destination writes JSON documents to a MongoDB collection. It supports upserts, transactions, and two JSON input modes.

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Schema Requirement

The source schema must contain a single field named _json of type string. Each value in this field is a JSON document that will be written to the target collection.

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JSON Modes

The JSON input mode is controlled by everyRowContainsObject in the source fileAttributes.jsonAttributes:
ValueDescription
trueEach line of the file is a separate JSON document (newline-delimited JSON). Default.
falseThe file contains a single JSON array; each element becomes a separate document.

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Upsert with Compound Keys

Specify one or more fields in keyFields to perform an upsert instead of a plain insert. The pipeline matches existing documents by the compound key formed from these fields. If a matching document exists it is replaced; otherwise a new document is inserted.

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Truncate Before Write

Set truncateBeforeWrite to true to delete all documents from the target collection before writing. This effectively replaces the entire collection on each run.

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Transaction Support

All write operations execute inside a MongoDB transaction. If any error occurs during the write, the transaction is aborted and no partial data is persisted.

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Configuration Example

{
  "name": "events_mongodb",
  "source": { "..." : "..." },
  "destination": {
    "database": {
      "dbName": "analytics",
      "table": "events",
      "useMongoDB": true,
      "keyFields": ["event_id", "source"],
      "truncateBeforeWrite": false,
      "useTransaction": true
    }
  }
}
MongoDB connection credentials are configured globally in application.yaml via secrets.mongoDbSecretName. See Configuration Reference for Vault secret format.

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Field Reference

FieldRequiredDefaultDescription
dbNameyesTarget database name
tableyesTarget collection name
useMongoDByesfalseMust be true to enable MongoDB destination
keyFieldsnoArray of field names forming the compound upsert key
truncateBeforeWritenofalseDelete all documents before writing
useTransactionnofalseWrap all writes in a MongoDB transaction