API reference / @node-ts/bus-postgres / PostgresPersistence

Class: PostgresPersistence

Defined in: packages/bus-postgres/src/postgres-persistence.ts:82

Infrastructure that provides the ability to persist workflow state for long running processes.

Workflow state is passed to and returned from the persistence as plain JSON values (Dates as ISO strings, Maps as objects, Sets as arrays and bigints as strings). The bus converts it to and from its classes with its own serializer and message types, so one persistence instance can be shared by several buses. A shared persistence is prepared and initialized by each bus, and only disposed by the last bus that uses it.

Implements

• Persistence

Constructors

Constructor

new PostgresPersistence(configuration, postgres?): PostgresPersistence;

Defined in: packages/bus-postgres/src/postgres-persistence.ts:85

Parameters

Parameter	Type
configuration	PostgresConfiguration
postgres	Pool

Returns

PostgresPersistence

Methods

dispose()

dispose(): Promise<void>;

Defined in: packages/bus-postgres/src/postgres-persistence.ts:103

If provided, will dispose any resources related to the persistence. This is where things like closing database connections should occur.

Returns

Promise<void>

Implementation of

Persistence.dispose

---

getWorkflowState()

getWorkflowState<WorkflowStateType, MessageType>(
   workflowStateConstructor, 
   messageMap, 
   message, 
   attributes, 
   includeCompleted?
): Promise<WorkflowStateType[]>;

Defined in: packages/bus-postgres/src/postgres-persistence.ts:126

Retrieves all workflow state models that match the given messageMap criteria

Type Parameters

Type Parameter
WorkflowStateType extends WorkflowState
MessageType extends Message

Parameters

Parameter	Type	Default value	Description
workflowStateConstructor	ClassConstructor<WorkflowStateType>	undefined	The workflow model type to retrieve
messageMap	MessageWorkflowMapping<MessageType, WorkflowStateType>	undefined	How the message is mapped to workflow state models
message	MessageType	undefined	The message to map to workflow state
attributes	MessageAttributes	undefined	-
includeCompleted	boolean	false	If completed workflow state items should also be returned. False by default

Returns

Promise<WorkflowStateType[]>

the matching workflow state as it was saved. The bus restores its classes, so it doesn't need to be converted.

Implementation of

Persistence.getWorkflowState

---

initialize()

initialize(): Promise<void>;

Defined in: packages/bus-postgres/src/postgres-persistence.ts:96

If provided, initializes the persistence implementation. This is where database connections are started.

Returns

Promise<void>

Implementation of

Persistence.initialize

---

initializeWorkflow()

initializeWorkflow<WorkflowStateType>(workflowStateConstructor, messageWorkflowMappings): Promise<void>;

Defined in: packages/bus-postgres/src/postgres-persistence.ts:109

Allows the persistence implementation to set up its internal structure to support the workflow state that it will be persisting. Typically for a database this could mean setting up the internal table schema to support persisting of each of the workflow state models.

Type Parameters

Type Parameter
WorkflowStateType extends WorkflowState

Parameters

Parameter	Type
workflowStateConstructor	ClassConstructor<WorkflowStateType>
messageWorkflowMappings	MessageWorkflowMapping<Message, WorkflowState>[]

Returns

Promise<void>

Implementation of

Persistence.initializeWorkflow

---

prepare()

prepare(coreDependencies): void;

Defined in: packages/bus-postgres/src/postgres-persistence.ts:90

An optional function that is called before startup that will provide core dependencies to the persistence. This can be used to fetch loggers etc that are used in initialization steps. A persistence shared by several buses is prepared by each of them.

Parameters

Parameter	Type	Description
coreDependencies	CoreDependencies	the dependencies of the bus that's preparing the persistence

Returns

void

Implementation of

Persistence.prepare

---

saveWorkflowState()

saveWorkflowState<WorkflowStateType>(workflowState): Promise<void>;

Defined in: packages/bus-postgres/src/postgres-persistence.ts:184

Saves a new workflow state model or updates an existing one. Persistence implementations should take care to observe the change in $version of the workflow state model when persisting to ensure race conditions don't occur.

Type Parameters

Type Parameter
WorkflowStateType extends WorkflowState

Parameters

Parameter	Type	Description
workflowState	WorkflowStateType	the workflow state as plain JSON values, ready to store as it is

Returns

Promise<void>

Implementation of

Persistence.saveWorkflowState