PostgresExternalService
An ExternalService wrapping a PostgreSQL database.
Expose the tables of a PostgreSQL database as collections in the Skip runtime.
For a usage example, refer here.
Remarks
Subscription params must include a field key of type { col: string, type: PostgresPKey } specifying the Postgres column to serve as key in Skip collections
Subscription params may also specify syncHistoricData: false to receive only new rows as they are created, for use with append-only tables whose history is not needed.
Implements
ExternalService
Constructors
new PostgresExternalService()
new PostgresExternalService(db_config): PostgresExternalService
Parameters
| Parameter | Type | Description |
|---|---|---|
db_config | { database: string; host: string; password: string; port: number; user: string; } | Configuration of database to which to connect. |
db_config.database | string | Name of database to which to connect. |
db_config.host | string | Host serving database. |
db_config.password | string | Password for user. |
db_config.port | number | Port on which database server listens. |
db_config.user | string | User as whom to authenticate. |
Returns
Methods
getClient()
getClient(): Client
The underlying PostgreSQL client, exposed for monitoring and diagnostics.
Returns
Client
The pg.Client used by this service.
getOpenInstances()
getOpenInstances(): Set<string>
Resource instances whose change-notification channels are currently set up.
Returns
Set<string>
A copy of the set of open resource instance identifiers.
isConnected()
isConnected(): boolean
Returns
boolean
shutdown()
shutdown(): Promise<void>
Shutdown the external service.
Returns
Promise<void>
Implementation of
ExternalService.shutdown
subscribe()
subscribe(
instance,
resource,
params,
callbacks): Promise<void>
Subscribe to a resource provided by the external service.
Parameters
| Parameter | Type | Description |
|---|---|---|
instance | string | Instance identifier of the external resource. |
resource | string | Name of the PostgreSQL table to expose as a resource. |
params | { key: { col: string; type: PostgresPKey; }; syncHistoricData: boolean; } | Parameters of the external resource. |
params.key | { col: string; type: PostgresPKey; } | (Required) Object describing the Postgres column that should be used as the key in the resulting collection |
params.key.col | string | Postgres column whose value is to be used as the collection key |
params.key.type | PostgresPKey | Postgres data type of col, which must be a text, integer, or serial type. (i.e. one of TEXT, SERIAL, SERIAL2, SERIAL4, SERIAL8, BIGSERIAL, SMALLSERIAL, INTEGER, INT, INT2, INT4, INT8, BIGINT, or SMALLINT) |
params.syncHistoricData? | boolean | (Optional) Boolean flag, true by default. If false, Skip will ignore pre-existing data and only synchronize updates after subscription. |
callbacks | { error: (error) => void; update: (updates, isInit) => Promise<void>; } | Callbacks to react on error/loading/update. |
callbacks.error | (error) => void | Error callback. |
callbacks.update | (updates, isInit) => Promise<void> | Update callback. |
Returns
Promise<void>
Implementation of
ExternalService.subscribe
unsubscribe()
unsubscribe(instance): void
Unsubscribe from a resource provided by the external service.
Parameters
| Parameter | Type | Description |
|---|---|---|
instance | string | Instance identifier of the external resource. |
Returns
void
Implementation of
ExternalService.unsubscribe