---
title: "lzb.constructor.post-change"
description: "JS action `lzb.constructor.post-change` of the Lazy Blocks WordPress plugin."
url: "https://www.lazyblocks.com/docs/js-actions/lzb-constructor-post-change/"
source: "js-actions/lzb-constructor-post-change.mdx"
---
# lzb.constructor.post-change

Action fired while the block builder watches the save state of the block post. Hook it to push data of your own to the server at the moment the block itself is saved.

## Attributes

| Name   | Type       | Description                                                               |
| ------ | ---------- | ------------------------------------------------------------------------- |
| `data` | **Object** | `isSavingPost`, `isAutosavingPost`, `shouldUpdate`, `blockData`, `postId` |

| Name               | Type        | Description                                                            |
| ------------------ | ----------- | ---------------------------------------------------------------------- |
| `isSavingPost`     | **Boolean** | the editor is saving right now                                         |
| `isAutosavingPost` | **Boolean** | the save in flight is an autosave                                      |
| `shouldUpdate`     | **Boolean** | a save that was not an autosave has just finished                      |
| `blockData`        | **Object**  | current block settings, with `slug`, `icon`, `category` and `controls` |
| `postId`           | **Number**  | ID of the `lazyblocks` post being edited                               |

The action sits in a `useEffect` keyed on `isSavingPost`, `isAutosavingPost`, `postId` and `blockData`, so it runs on every change of any of them and not only on save. Typing one character into a control label fires it. `shouldUpdate` is the only argument that marks a finished save, and it is true exactly once per save that was not an autosave.

It fires immediately after the builder issues its own `/lazy-blocks/v1/update-block-data/` request, not after that request resolves. A handler that reads the block back over REST can still see the previous values.

## Usage

```js title="JS"
let myDataChanged = false;

wp.hooks.addAction(
  "lzb.constructor.post-change",
  "my.custom.namespace",
  function ({ shouldUpdate, postId }) {
    if (!shouldUpdate || !myDataChanged) {
      return;
    }

    wp.apiFetch({
      path: "/my-plugin/v1/block-saved/",
      method: "POST",
      data: { post_id: postId },
    }).then(() => {
      myDataChanged = false;
    });
  },
);
```

Without the `shouldUpdate` gate the handler runs on every keystroke in the builder, which is how a request per character ends up in the network tab. Pro uses exactly this shape to write its block collections once the block post is saved.

## Documentation Index
> Fetch the complete documentation index at: https://www.lazyblocks.com/llms.txt
> Fetch every page in a single file at: https://www.lazyblocks.com/llms-full.txt