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subscribe

Subscribe to real-time data from the Flow blockchain and automatically decode the responses.

This is a utility function used for subscribing to real-time data from the WebSocket Streaming API. Data returned will be automatically decoded via the 'decode' function.

Available topics include: events, blocks, block_headers, block_digests, transaction_statuses, account_statuses.

Import​

You can import the entire package and access the function:


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import * as sdk from "@onflow/sdk"
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sdk.subscribe(subscribeParams, opts)

Or import directly the specific function:


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import { subscribe } from "@onflow/sdk"
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subscribe(subscribeParams, opts)

Usage​


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import * as fcl from "@onflow/fcl";
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import { SubscriptionTopic } from "@onflow/sdk";
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// Subscribe to events
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const subscription = fcl.subscribe({
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topic: SubscriptionTopic.EVENTS,
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args: {
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eventTypes: ["A.7e60df042a9c0868.FlowToken.TokensWithdrawn"]
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},
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onData: (events) => {
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console.log("Received events:", events);
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},
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onError: (error) => {
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console.error("Subscription error:", error);
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}
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});
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// Subscribe to blocks
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const blockSubscription = fcl.subscribe({
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topic: SubscriptionTopic.BLOCKS,
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args: {
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blockStatus: "finalized"
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},
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onData: (block) => {
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console.log("New block:", block);
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},
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onError: (error) => {
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console.error("Block subscription error:", error);
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}
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});
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// Later, to unsubscribe:
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subscription.unsubscribe();
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blockSubscription.unsubscribe();

Parameters​

subscribeParams​

  • Type:

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SubscribeParams<T>

opts (optional)​

  • Type:

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{ node?: string; transport?: SdkTransport; }

  • Description: Additional options for the subscription

Returns​

Subscription

A subscription object that allows you to manage the subscription (e.g., to unsubscribe later)

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