add-relation

# Add Relation Connect two NocoDB tables with a Link field. Optionally add a Lookup so the linked record's display name is visible on the other side. How Link, Lookup and Rollup fields are built and verified is written down in `${CLAUDE_PLUGIN_ROOT}/skills/field-management/SKILL.md`; read it before the first step. ## Steps 1. Resolve both table IDs via `mcp__plugin_nocodb-dev_nocodb__getTablesList`. 2. Decide the cardinality (`relation_type`): - **bt** (belongs-to) — many-to-one. Each row on the "from" side links to one row on the "to" side. (Order belongs to Customer.) - **hm** (has-many) — one-to-many. Each row on the "from" side links to many rows on the "to" side. (Customer has-many Orders.) - **mm** (many-to-many) — both sides link to many. (Tags ↔ Articles.) - **oo** (one-to-one) — each row links to exactly one row on the other side. 3. Snapshot both tables before: ``` mcp__plugin_nocodb-dev_nocodb__getTableSchema tableId: <fromTableId> mcp__plugin_nocodb-dev_nocodb__getTableSchema tableId: <toTableId> ``` 4. Create the link field on the "from" table. On Cloud / licensed, `listTools category: "fields"` then `callTool name: "createField"` with `arguments: { tableId: "<fromTableId>", field: { … } }`; on Community Edition (or as a fallback) use REST with the same object as the body: ```bash curl -sS -X POST \ -H "xc-token: ${NOCODB_TOKEN}" -H "Content-Type: application/json" \ -d '{ "title": "<linkName>", "type": "LinkToAnotherRecord", "options": { "relation_type": "<bt|hm|mm|oo>", "related_table_id": "<toTableId>" } }' \ "${NOCODB_URL}/api/v3/meta/bases/${BASE_ID}/tables/<fromTableId>/fields" ``` 5. Verify the inverse link auto-appeared on the "to" table: ``` mcp__plugin_nocodb-dev_nocodb__getTableSchema tableId: <toTableId> ``` 6. (Optional) Ask the user if they want a Lookup that surfaces a field from the linked side. If yes: - Find the link's field ID on the "from" side (from step 5's snapshot). - Find the field ID to look up on the "to" side. - Create it with the same `createField` call (or REST `POST`) using: ```json { "title": "<lookupTitle>", "type": "Lookup", "options": { "related_field_id": "<fromLinkFieldId>", "related_table_lookup_field_id": "<toFieldId>" } } ``` 7. Verify both fields appear in the schema, and (optionally) link one record to confirm. ## Reference - `Skill nocodb-dev:field-management` — workflow + payloads - `Skill nocodb-dev:mcp-patterns` — the MCP-first contract (Cloud / licensed) and the REST fallback - `Skill nocodb-dev:cli-reference` — `curl` recipes for relations (`references/relations-links.md`) - `Skill nocodb-dev:examples` — CRM and e-commerce relation walkthroughs (`references/scenarios/`) ## Watch Out - For `mm`, NocoDB creates a hidden join table. If you need per-relation metadata (quantity, line price), use an explicit join table (see `examples/references/scenarios/ecommerce-relations.md`). - `options` needs both `relation_type` and `related_table_id`; flat keys outside `options` are rejected. - Don't try to PATCH a Lookup config to point at a not-yet-existing link — NocoDB rejects with 400.