Type alias Exchange

Type declaration

• • (input): ExchangeIO

  • Exchanges are both extensions for a Client and part of the control-flow executing Operations.

    Remarks

    Exchanges are responsible for the pipeline in urql that accepts Operations and returns OperationResults. They take care of adding functionality to a Client, like deduplication, caching, and fetching (i.e. making GraphQL requests).

    When passed to the Client, they're instantiated with the ExchangeInput object and return an ExchangeIO function, which is a mapping function that receives a stream of Operations and returns a stream of OperationResults.

    Like middleware, exchanges are composed, calling each other in a pipeline-like fashion, which is facilitated by exchanges calling forward, which is set to the next exchange's ExchangeIO function in the pipeline.

    See

    • https://urql.dev/goto/docs/architecture/#the-client-and-exchanges for more information on Exchanges.
    • https://urql.dev/goto/docs/advanced/authoring-exchanges on how Exchanges are authored.

    Example

    import { pipe, onPush } from 'wonka';
    import { Exchange } from '@urql/core';
    
    const debugExchange: Exchange => {
      return ops$ => pipe(
        ops$,
        onPush(operation => console.log(operation)),
        forward,
        onPush(result => console.log(result)),
      );
    };
    Copy

    Parameters

    • input: ExchangeInput

    Returns ExchangeIO