call_method

Calls a method on a Connector and emits the result downstream — the primary step for all I/O.

When to use it

Use call_method whenever a step needs to read from or write to a Connector: as the pipeline source (read, find, list) or as a per-item write (create, update, upsert). When you need to call a connector per item and keep the original item's fields, use the $callMethod JSONata function inside a transform instead — but only for bounded lookups such as find_one or count, because $callMethod buffers its entire result into memory.

Configuration

Any other key in the config produces the validation warning Unknown key '<key>' in call_method config.

Example

name: fetch-tickets
connectors:
  source:
    type: freshdesk
  destination:
    type: sqlite
steps:
  - name: list_tickets
    type: call_method
    config:
      connector: source
      method: list
      args:
        resource: tickets
 
  - name: save_ticket
    type: call_method
    config: |
      {
        "connector": "destination",
        "method": "upsert",
        "args": { "table": "tickets", "data": input, "conflict_columns": ["id"] }
      }

The first step uses a static config because it references nothing from the stream. The second uses a JSONata string config (config: |) because it references input.

Behavior notes

• Array results stream with backpressure. When the method returns an array or an async iterable, each element is emitted downstream as a separate item. Async iterables are consumed lazily, so a slow downstream step pauses the source instead of buffering pages in memory.
• The return value replaces the input item. After a call_method step, input for the next step is the method's result — the incoming item's fields are gone. Carry needed fields forward in a prior transform and read them via steps.<name>.output.
• Return-value contract: undefined or an empty array drops the item; a non-empty array fans out; anything else is emitted as a single item.
• A config that evaluates to null or undefined passes the input through unchanged — the item is not dropped.
• The task's abort signal is passed to the connector call, so stopping a run cancels in-flight requests.

Related

• transform — shape results, or enrich per item with $callMethod
• Task YAML schema — shared step keys like concurrency and error_handling
• Reading and writing data — source and write patterns with call_method