# get_destination_id

> Source: https://docs.clonepartner.com/reference/steps/get-destination-id/

<!-- sources: src/steps/get-destination-id-step.ts, src/steps/types.ts, references/envoy/patterns.md, references/envoy/step-types.md -->

# get_destination_id

Looks up a source-to-destination ID mapping from the mapping store, so a pipeline can skip records that were already migrated.

## When to use it

Use `get_destination_id` with `skip_if` and [set_destination_id](/reference/steps/set-destination-id/) to build the manual dedup pattern. For new tasks, prefer [sync_record](/reference/steps/sync-record/) — it combines the mapping lookup, hash-based change detection, create/update, and mapping persistence in one composite step.

## Configuration

| Key | Type | Required | Default | Description |
|---|---|---|---|---|
| `connector` | string | Yes | — | Connector slot for the mapping store; the connector type must support ID mapping. |
| `resource` | string | Yes | — | Resource or entity name the mapping is scoped to. |
| `source_id` | string | Yes | — | Source system ID to look up. Coerced to a string. |

## Example

```yaml
name: migrate-accounts
output: none
connectors:
  source:
    type: csv
  destination:
    type: dynamics365
  mapping_db:
    type: sqlite
steps:
  - name: read_accounts
    type: call_method
    config:
      connector: source
      method: read
      args:
        resource: accounts

  - name: check_existing
    type: get_destination_id
    config: |
      {
        "connector": "mapping_db",
        "resource": "account",
        "source_id": input.account_id
      }

  - name: create_account
    type: call_method
    skip_if: "steps.check_existing.output.destination_id != null"
    config: |
      {
        "connector": "destination",
        "method": "create",
        "args": { "resource": "accounts", "data": input }
      }
```

## Behavior notes

- **The lookup returns `destination_id` and `hash`** — both null when no mapping exists. Downstream steps read them as `steps.<name>.output.destination_id` and `steps.<name>.output.hash`.
- **The input record is preserved.** When the input is a plain object, the step emits the input merged with the lookup result (lookup fields take precedence), so downstream expressions still see the original source fields. A non-object input is replaced by the lookup result alone.
- The `hash` value supports change detection: compare it with a hash from [compute_hash](/reference/steps/compute-hash/) in a `skip_if` to update only changed records.

## Related

- [set_destination_id](/reference/steps/set-destination-id/) — the write half of the mapping pair
- [sync_record](/reference/steps/sync-record/) — the preferred composite replacement
- [Idempotent sync and the mapping DB](/building/idempotent-sync/) — the dedup pattern end to end