Cayenne DB Import

cayenne-db-import

Import a database schema into a Cayenne DataMap using the mcp__cayenne__dbimport_run MCP tool. If a DBConnector is already stored in preferences for the DataMap the import runs directly without any GUI interaction. When the connection has not been configured yet, the workflow launches CayenneModeler and walks the user through the dialog once to save the connection, then re-runs dbimport_run.

Required reading

• ${CLAUDE_PLUGIN_ROOT}/references/project-layout.md — locate or create the project descriptor.
• ${CLAUDE_PLUGIN_ROOT}/references/dbimport-config.md — field semantics for every dialog screen, so you can explain options in user terms.
• ${CLAUDE_PLUGIN_ROOT}/references/mcp-tools.md — dbimport_run and open_project tool references and failure modes.

Step 1 — Confirm scope

Ask the user (one question, only if not obvious from the request):

• Are they reverse-engineering into a new DataMap, or adding/updating entities in an existing DataMap?

Step 2 — Locate or create the project

Follow project-layout.md to find the existing cayenne-*.xml. If none exists, the user is starting from scratch:

• Either generate a minimal descriptor first (use cayenne-modeling's patterns — namespace http://cayenne.apache.org/schema/12/domain, project-version="12", one empty <map name="..."/> plus a sibling empty *.map.xml), or
• Tell the user to use File → New Project inside the Modeler once it's open.

The descriptor path needs to be absolute when passed to the MCP tools.

Step 3 — Run dbimport_run

Call the MCP tool:

mcp__cayenne__dbimport_run({ "projectPath": "<absolute path to cayenne-*.xml>", "dataMap": "<DataMap name>" })

If the tool is not available (server not registered), surface cayenne-mcp-server/README.md and stop. Do not suggest mvn cayenne:cdbimport or any Gradle equivalent — those build plugins are out of scope.

Interpreting the result

• imported — success. Surface the summary counters (entities added/removed/modified, relationships added) to the user.
• up_to_date — the DataMap already matches the database. Tell the user nothing changed.
• error — import started but failed mid-run. Show the error.message and the partial summary.
• validation_failed — a pre-flight check failed. Use the error.code to guide next steps (see below).

Validation failures and their remediation

Step 4 — Configure the connection (first-time only)

This step is only needed when dbimport_run returns dbconnector_not_configured.

4a — Launch the Modeler

mcp__cayenne__open_project({ "projectPath": "<absolute path to cayenne-*.xml>" })

If open_project returns a non-ok status, surface the error code; common ones are modeler_not_found, project_not_found, handshake_timeout. Don't retry blindly — diagnose first.

4b — Walk the user through the dialog

The user now has the Modeler open. Give them the exact GUI sequence:

1. DataMap → DB Import tab
2. Data Source dialog:
   • JDBC Driver — e.g., org.postgresql.Driver
   • DB URL — full JDBC URL
   • User Name / Password — credentials
   • Cayenne Adapter (optional, autodetected for known DBs)
   • Click Test Connection, then Continue.
3. Configure screen — set table/column/procedure filters:
   • Include/exclude regex patterns under the relevant catalog/schema.
   • Table Types — usually TABLE; add VIEW if needed.
4. Naming screen:
   • Naming Strategy, Strip from Table Names, Default Package, Meaningful PK Tables.
   • See dbimport-config.md for what each does.
5. Other Options — toggles for skipPrimaryKeyLoading, skipRelationshipsLoading, etc.
6. Click Save (not Run Import — the goal here is to save the connection, not run the import through the GUI).

After the user saves, the DBConnector is written to CayenneModeler preferences.

4c — Re-run dbimport_run

Go back to Step 3 and call dbimport_run again. This time it should find the saved connection and proceed.

Step 5 — Confirm and follow up

Once the import succeeds:

• Tell the user to save the project in the Modeler if it is open (File → Save). The dialog settings persist as a <dbImport> block inside the DataMap for repeat runs.
• Hand off to cayenne-cgen to regenerate Java classes for the new/changed entities. Quote the DataMap name so the cgen skill can pass it to cgen_run.
• If the imported names look awkward (run-together words, team1-style relationship names, a table prefix leaking into relationships), you can offer the cayenne-model-naming skill to polish them — ideally before cgen. Only run it if the user asks; do not invoke it automatically.
• If the DB has columns that don't follow the user's preferred naming, recommend tweaking the naming strategy and re-running.

Anti-patterns

• Do not suggest mvn cayenne:cdbimport, the Gradle cdbimport task, or hand-running the cayenne-dbsync Java APIs. dbimport_run is the only supported execution path.
• Do not try to hand-write a DataMap from a DB schema description as a substitute — the import handles JDBC types, PK detection, FK relationships, and naming consistently. Hand-rolling produces subtle mistakes.
• Do not enable forceDataMapCatalog / forceDataMapSchema defensively. They suppress legitimate DB metadata and cause hard-to-debug issues in multi-catalog setups.
• Do not offer reverse engineering without MCP — if the server isn't connected, point at cayenne-mcp-server/README.md and stop.
• Do not run the import through the Modeler GUI dialog when dbimport_run is available — the GUI path is only for the first-time connection setup.