@coasys/ad4m / Exports / QuerySubscriptionProxy
Class: QuerySubscriptionProxy
Proxy object for a subscribed Prolog query that provides real-time updates
This class handles:
- Keeping the subscription alive by sending periodic keepalive signals
- Managing callbacks for result updates
- Subscribing to query updates via GraphQL subscriptions
- Maintaining the latest query result
The subscription will remain active as long as keepalive signals are sent. Make sure to call dispose() when you're done with the subscription to clean up resources and stop keepalive signals.
Example usage:
const subscription = await perspective.subscribeInfer("my_query(X)");
console.log("Initial result:", subscription.result);
// Set up callback for updates
const removeCallback = subscription.onResult(result => {
console.log("New result:", result);
});
// Later: clean up
subscription.dispose();Table of contents
Constructors
Properties
Accessors
Methods
Constructors
constructor
• new QuerySubscriptionProxy(uuid, subscriptionId, initialResult, client)
Creates a new query subscription
Parameters
| Name | Type | Description |
|---|---|---|
uuid | string | The UUID of the perspective |
subscriptionId | string | The ID returned by the subscription mutation |
initialResult | AllInstancesResult | The initial query result |
client | PerspectiveClient | The PerspectiveClient instance to use for communication |
Defined in
perspectives/PerspectiveProxy.ts:66
Properties
#callbacks
• Private #callbacks: Set<QueryCallback>
Defined in
perspectives/PerspectiveProxy.ts:54
#client
• Private #client: PerspectiveClient
Defined in
perspectives/PerspectiveProxy.ts:53
#disposed
• Private #disposed: boolean = false
Defined in
perspectives/PerspectiveProxy.ts:58
#keepaliveTimer
• Private #keepaliveTimer: number
Defined in
perspectives/PerspectiveProxy.ts:55
#latestResult
• Private #latestResult: AllInstancesResult
Defined in
perspectives/PerspectiveProxy.ts:57
#subscriptionId
• Private #subscriptionId: string
Defined in
perspectives/PerspectiveProxy.ts:52
#unsubscribe
• Private Optional #unsubscribe: () => void
Type declaration
▸ (): void
Returns
void
Defined in
perspectives/PerspectiveProxy.ts:56
#uuid
• Private #uuid: string
Defined in
perspectives/PerspectiveProxy.ts:51
Accessors
result
• get result(): AllInstancesResult
Get the latest query result
This returns the most recent result from the query, which could be either:
- The initial result from when the subscription was created
- The latest update received through the subscription
Returns
The latest query result as a string (usually a JSON array of bindings)
Defined in
perspectives/PerspectiveProxy.ts:113
Methods
#notifyCallbacks
▸ Private #notifyCallbacks(result): void
Internal method to notify all callbacks of a new result
Parameters
| Name | Type |
|---|---|
result | AllInstancesResult |
Returns
void
Defined in
perspectives/PerspectiveProxy.ts:142
dispose
▸ dispose(): void
Clean up the subscription and stop keepalive signals
This method:
- Stops the keepalive timer
- Unsubscribes from GraphQL subscription updates
- Clears all registered callbacks
After calling this method, the subscription is no longer active and will not receive any more updates. The instance should be discarded.
Returns
void
Defined in
perspectives/PerspectiveProxy.ts:162
onResult
▸ onResult(callback): () => void
Add a callback that will be called whenever new results arrive
The callback will be called immediately with the current result, and then again each time the query results change.
Parameters
| Name | Type | Description |
|---|---|---|
callback | QueryCallback | Function that takes a result string and processes it |
Returns
fn
A function that can be called to remove this callback
Example:
const removeCallback = subscription.onResult(result => {
const bindings = JSON.parse(result);
console.log("New bindings:", bindings);
});
// Later: stop receiving updates
removeCallback();▸ (): void
Add a callback that will be called whenever new results arrive
The callback will be called immediately with the current result, and then again each time the query results change.
Returns
void
A function that can be called to remove this callback
Example:
const removeCallback = subscription.onResult(result => {
const bindings = JSON.parse(result);
console.log("New bindings:", bindings);
});
// Later: stop receiving updates
removeCallback();Defined in
perspectives/PerspectiveProxy.ts:136