Allow ChromaClient to be initialized outside Chroma Vector Store

[shripadk]

While trying out Chroma integration I stumbled upon the following error:

Error: Please install chromadb as a dependency with, e.g. `npm install -S chromadb`

Even though I had already installed chromadb.

When I dug into the source, I was surprised to see that ChromaClient is being required and initialized directly here: https://github.com/hwchase17/langchainjs/blob/main/langchain/src/vectorstores/chroma.ts#L10-L15

This doesn't work well with cli tools like tsx.

Any reason why this is the case? Why can't we just pass our own initialized ChromaClient to fromDocuments? Also, this would cause an issue when ChromaDB has a different basePath and is hosted on a remote machine as currently there is no way to configure parameters that are passed to ChromaClient.

This is already being done with PineconeStore where we pass in the index initialized outside the PineconeStore itself.

Keeping the API consistent with PineconeStore, my suggestion would be to have this function signature for fromDocuments (and fromTexts too):

static fromDocuments(
  client: ChromaClient,
  docs: Document[],
  embeddings: Embeddings,
  collectionName?: string,
  url?: string
): Promise<Chroma>;

And of course remove the need to initialize ChromaClient directly and let us pass the initialized client instead.

[shripadk]

I am currently doing it this way though I prefer using Chroma.fromDocuments instead:

const client = new ChromaClient();

const chroma = new Chroma(
  {
    collectionName,
    numDimensions,
  },
  embeddings,
  client
);

await chroma.addDocuments(docs);

[nfcampos]

hi @shripadk thanks, this was something we missed when converting the library to ESM, thanks for pointing it out, fixing it here #220

[shripadk]

@nfcampos Thank you!