Dispatch direct-upload events on attachment uploads

When using Action Text's rich textarea,  it's possible to attach files to the
editor. Previously, that action didn't dispatch any events, which made it hard
to react to the file uploads. For instance, if an upload failed, there was no
way to notify the user about it, or remove the attachment from the editor.

This commits adds new events - `direct-upload:start`, `direct-upload:progress`,
and `direct-upload:end` - similar to how Active Storage's direct uploads work.

Closes rails#37793
Supersedes rails#37794

Co-authored-by: Brad Rees <[email protected]>

Author: MatheusRich

actiontext/CHANGELOG.md

@@ -1,3 +1,15 @@
+*   Dispatch direct-upload events on attachment uploads
+
+    When using Action Text's rich textarea,  it's possible to attach files to the
+    editor. Previously, that action didn't dispatch any events, which made it hard
+    to react to the file uploads. For instance, if an upload failed, there was no
+    way to notify the user about it, or remove the attachment from the editor.
+
+    This commits adds new events - `direct-upload:start`, `direct-upload:progress`,
+    and `direct-upload:end` - similar to how Active Storage's direct uploads work.
+
+    *Matheus Richard*, *Brad Rees*
+
 *   Add `store_if_blank` option to `has_rich_text`
 
     Pass `store_if_blank: false` to not create `ActionText::RichText` records when saving with a blank attribute, such as from an optional form parameter.

actiontext/app/assets/javascripts/actiontext.esm.js

@@ -1,4 +1,4 @@
-import { DirectUpload } from "@rails/activestorage"
+import { DirectUpload, dispatchEvent } from "@rails/activestorage"
 
 export class AttachmentUpload {
   constructor(attachment, element) {
@@ -9,24 +9,29 @@ export class AttachmentUpload {
 
   start() {
     this.directUpload.create(this.directUploadDidComplete.bind(this))
+    this.dispatch("start")
   }
 
   directUploadWillStoreFileWithXHR(xhr) {
     xhr.upload.addEventListener("progress", event => {
       const progress = event.loaded / event.total * 100
       this.attachment.setUploadProgress(progress)
+      if (progress) {
+        this.dispatch("progress", { progress: progress })
+      }
     })
   }
 
   directUploadDidComplete(error, attributes) {
     if (error) {
-      throw new Error(`Direct upload failed: ${error}`)
+      this.dispatchError(error)
+    } else {
+      this.attachment.setAttributes({
+        sgid: attributes.attachable_sgid,
+        url: this.createBlobUrl(attributes.signed_id, attributes.filename)
+      })
+      this.dispatch("end")
     }
-
-    this.attachment.setAttributes({
-      sgid: attributes.attachable_sgid,
-      url: this.createBlobUrl(attributes.signed_id, attributes.filename)
-    })
   }
 
   createBlobUrl(signedId, filename) {
@@ -35,6 +40,18 @@ export class AttachmentUpload {
       .replace(":filename", encodeURIComponent(filename))
   }
 
+  dispatch(name, detail = {}) {
+    detail.attachment = this.attachment
+    return dispatchEvent(this.element, `direct-upload:${name}`, { detail })
+  }
+
+  dispatchError(error) {
+    const event = this.dispatch("error", { error })
+    if (!event.defaultPrevented) {
+      alert(error);
+    }
+  }
+
   get directUploadUrl() {
     return this.element.dataset.directUploadUrl
   }

actiontext/app/assets/javascripts/actiontext.js

@@ -2,7 +2,8 @@ import { start } from "./ujs"
 import { DirectUpload } from "./direct_upload"
 import { DirectUploadController } from "./direct_upload_controller"
 import { DirectUploadsController } from "./direct_uploads_controller"
-export { start, DirectUpload, DirectUploadController, DirectUploadsController }
+import { dispatchEvent } from "./helpers"
+export { start, DirectUpload, DirectUploadController, DirectUploadsController, dispatchEvent }
 
 function autostart() {
   if (window.ActiveStorage) {

actiontext/app/javascript/actiontext/attachment_upload.js

@@ -233,7 +233,6 @@ To customize the HTML rendered for embedded images and other attachments (known
 as blobs), edit the `app/views/active_storage/blobs/_blob.html.erb` template
 created by the installer:
 
-
 ```html+erb
 <%# app/views/active_storage/blobs/_blob.html.erb %>
 <figure class="attachment attachment--<%= blob.representable? ? "preview" : "file" %> attachment--<%= blob.filename.extension %>">
@@ -270,6 +269,14 @@ encounter when working with Action Text and Active Storage is that images do not
 render correctly in the editor. This is usually due to the `libvips` dependency
 not being installed.
 
+#### Attachment Direct Upload JavaScript Events
+
+| Event name | Event target | Event data (`event.detail`) | Description |
+| --- | --- | --- | --- |
+| `direct-upload:start` | `<input>` | `{id, file}` | A direct upload is starting. |
+| `direct-upload:progress` | `<input>` | `{id, file, progress}` | As requests to store files progress. |
+| `direct-upload:error` | `<input>` | `{id, file, error}` | An error occurred. An `alert` will display unless this event is canceled. |
+| `direct-upload:end` | `<input>` | `{id, file}` | A direct upload has ended. |
 
 ### Signed GlobalID