feat: Enable unfurling comments in Slack (#6716)

server/models/Comment.ts

@@ -1,3 +1,4 @@
+import { Node } from "prosemirror-model";
 import { InferAttributes, InferCreationAttributes } from "sequelize";
 import {
   DataType,
@@ -9,7 +10,9 @@ import {
   DefaultScope,
 } from "sequelize-typescript";
 import type { ProsemirrorData } from "@shared/types";
+import ProsemirrorHelper from "@shared/utils/ProsemirrorHelper";
 import { CommentValidation } from "@shared/validations";
+import { schema } from "@server/editor";
 import Document from "./Document";
 import User from "./User";
 import ParanoidModel from "./base/ParanoidModel";
@@ -71,6 +74,11 @@ class Comment extends ParanoidModel<
   @ForeignKey(() => Comment)
   @Column(DataType.UUID)
   parentCommentId: string;
+
+  public toPlainText() {
+    const node = Node.fromJSON(schema, this.data);
+    return ProsemirrorHelper.toPlainText(node, schema);
+  }
 }
 
 export default Comment;