How to copy a new yDoc into mongodb?

[huanghantao]

Here's my code:

  async duplicate(sourceFileId: string, destFileId: string): Promise<void> {
      const mdb = this.getMongodbPersistence();
      let sourceDocName = this.generateDocNameByFileId(sourceFileId);
      let destDocName = this.generateDocNameByFileId(destFileId);

      const sourceYdoc = await mdb.getYDoc(sourceDocName);
      const destYdoc = await mdb.getYDoc(destDocName);

      mdb.storeUpdate(destDocName, Y.encodeStateAsUpdate(sourceYdoc));
  }

However, the data stored in mongodb seems to be wrong. Can you guide me? I'm a novice, thank you！

[MaxNoetzold]

At first glance, your code appears to be fine. Could you please clarify what you mean when you say "the data stored in MongoDB seems to be incorrect"? Additionally, I can provide you with the code for how I would write the duplicate function. Perhaps it will be helpful:

const mdb = this.getMongodbPersistence();
const sourceDocName = this.generateDocNameByFileId(sourceFileId);
const destDocName = this.generateDocNameByFileId(destFileId);

const sourceYdoc = await mdb.getYDoc(sourceDocName);
const destYdoc = new Y.Doc();

const sourceStateVector = Y.encodeStateVector(sourceYdoc);
const diff = Y.encodeStateAsUpdate(destYdoc, sourceStateVector);

await mdb.storeUpdate(destDocName , diff);

tbh I am not an expert in the encoding of yjs updates either. Therefore, I cannot say for certain if my code is any different from yours. However, since both ydocs are not identical, I think that you need to "move" the update from one ydoc to the other. But again, I am not entirely sure.

I hope it helps.

[huanghantao]

@MaxNoetzold Thanks for your reply! I found a workable solution that seems to be working for now:

const mdb = this.getMongodbPersistence();
let sourceDocName = this.generateDocNameByFileId(sourceFileId);
let destDocName = this.generateDocNameByFileId(destFileId);

const sourceYdoc = await mdb.getYDoc(sourceDocName);
const destYdoc = await mdb.getYDoc(destDocName);

const sourceYArr = sourceYdoc.getArray<{ key: string; val: any }>(`${sourceFileId}`)
const sourceYStore = new YKeyValue(sourceYArr)

const records = sourceYStore.yarray.toJSON().map(({ val }) => ({ key: val.id, val: val }));

const destYArr = destYdoc.getArray<{ key: string; val: any }>(`${destFileId}`)
destYArr.insert(0, records)
mdb.storeUpdate(destDocName, Y.encodeStateAsUpdate(destYdoc));

But I'm not sure that's the best thing to do.