middleware

Adds custom logic to your Vue InstantSearch apps.

Signature

<ais-instant-search
  index-name="instant_search"
  :search-client="searchClient"
  :middlewares="middlewares"
>
  <!-- Widgets -->
</ais-instant-search>

About this widget

The middleware function returns an object with onStateChange, subscribe, and unsubscribe functions.

The middleware function doesn’t perform any actions itself but lets you inject logic into Vue InstantSearch, for example, sending events to Google Analytics. To send Algolia click and conversion events, use the insights middleware.

Requirements

• Vue InstantSearch v3.7.0 or later.

Examples

Vue

<template>
  <ais-instant-search
    index-name="instant_search"
    :search-client="searchClient"
    :middlewares="middlewares"
  >
    <!-- Widgets -->
  </ais-instant-search>
</template>

<script>
function middleware({ instantSearchInstance }) {
  return {
    onStateChange({ uiState }) {
      // Do something with `uiState` every time the state changes.
    },
    subscribe() {
      // Do something when the InstantSearch instance starts.
    },
    unsubscribe() {
      // Do something when the InstantSearch instance is disposed of.
    },
  };
}

export default {
  data() {
    return {
      // ...
      middlewares: [middleware],
    };
  },
};
</script>

Options

instantSearchInstance · object · required

You have access to the instance of instantsearch which lets you read values from the instance or call instance methods like addWidgets, setUiState, and refresh.

JavaScript

function middleware({ instantSearchInstance }) {
  return {
    onStateChange({ uiState }) {
      // ...
    },
    subscribe() {
      // ...
    },
    unsubscribe() {
      // ...
    },
  };
}

Hooks

onStateChange · ({ uiState }) => void · required

This function is called with uiState whenever the state changes.

JavaScript

function middleware({ instantSearchInstance }) {
  return {
    // ...
    onStateChange({ uiState }) {
      const indexName = "<your-index-name>";
      const { query } = uiState[indexName];
      const title = document.querySelector("<your-selector>");
      title.innerText = query ? `Query: ${query}` : `No query`;
    },
  };
}

subscribe · () => void · required

This function is called when the InstantSearch instance starts (when search.start() is called). This is where you can add event listeners, subscribe to an API, and run any side effects.

JavaScript

function middleware({ instantSearchInstance }) {
  let subscription;
  let listener;

  return {
    // ...
    subscribe() {
      subscription = someAPI.subscribe();

      listener = (event) => {
        // do something
      };
      document
        .querySelector("<your-selector>")
        .addEventListener("click", listener);
    },
  };
}

unsubscribe · () => void · required

This function is called when the InstantSearch instance is disposed of. You can clean up anything you initiated in the subscribe function.

JavaScript

function middleware({ instantSearchInstance }) {
  let subscription;
  let listener;

  return {
    // ...
    unsubscribe() {
      subscription.unsubscribe();

      document
        .querySelector("<your-selector>")
        .removeEventListener("click", listener);
    },
  };
}