Method command

src/cmap/connection.ts:872–937

(
    ns: MongoDBNamespace,
    cmd: Document,
    options?: CommandOptions,
    responseType?: T
  )

  ): Promise<Document>;

  override async command<T extends MongoDBResponseConstructor>(
    ns: MongoDBNamespace,
    cmd: Document,
    options?: CommandOptions,
    responseType?: T
  ): Promise<Document> {
    const { autoEncrypter } = this;
    if (!autoEncrypter) {
      throw new MongoRuntimeError('No AutoEncrypter available for encryption');
    }

    const serverWireVersion = maxWireVersion(this);
    if (serverWireVersion === 0) {
      // This means the initial handshake hasn't happened yet
      return await super.command<T>(ns, cmd, options, responseType);
    }

    // Save sort or indexKeys based on the command being run
    // the encrypt API serializes our JS objects to BSON to pass to the native code layer
    // and then deserializes the encrypted result, the protocol level components
    // of the command (ex. sort) are then converted to JS objects potentially losing
    // import key order information. These fields are never encrypted so we can save the values
    // from before the encryption and replace them after encryption has been performed
    const sort: Map<string, number> | null = cmd.find || cmd.findAndModify ? cmd.sort : null;
    const indexKeys: Map<string, number>[] | null = cmd.createIndexes
      ? cmd.indexes.map((index: { key: Map<string, number> }) => index.key)
      : null;

    const encrypted = await autoEncrypter.encrypt(ns.toString(), cmd, options);

    // Replace the saved values
    if (sort != null && (cmd.find || cmd.findAndModify)) {
      encrypted.sort = sort;
    }

    if (indexKeys != null && cmd.createIndexes) {
      for (const [offset, index] of indexKeys.entries()) {
        // @ts-expect-error `encrypted` is a generic "command", but we've narrowed for only `createIndexes` commands here
        encrypted.indexes[offset].key = index;
      }
    }

    const encryptedResponse = await super.command(
      ns,
      encrypted,
      options,
      // Eventually we want to require `responseType` which means we would satisfy `T` as the return type.
      // In the meantime, we want encryptedResponse to always be _at least_ a MongoDBResponse if not a more specific subclass
      // So that we can ensure we have access to the on-demand APIs for decorate response
      responseType ?? MongoDBResponse
    );

    const result = await autoEncrypter.decrypt(encryptedResponse.toBytes(), options);

    const decryptedResponse = responseType?.make(result) ?? deserialize(result, options);

    if (autoEncrypter[kDecorateResult]) {
      if (responseType == null) {