Retrieving folder contents efficiently using Google Drive API

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1

I’m working on a .NET web application that needs to let users browse their Google Drive folders and pick files for later use. The main issue I’m running into is getting all files from a specific directory without making tons of API calls.

Right now I’m stuck because the children endpoint only returns file IDs, not the actual file details I need for my interface. This means I have to make separate requests for each file which is really slow.

I tried using the query parameter approach but keep getting validation errors when I pass the folder ID directly. The files endpoint seems to ignore folder filtering completely and just dumps everything.

Is there a better way to fetch all files and subfolders from a specific parent directory in one API call? I need the metadata too, not just the references.

Here’s the kind of error I’m seeing:

{
  "error": {
    "errors": [{
      "domain": "global",
      "reason": "invalid",
      "message": "Invalid Value",
      "locationType": "parameter",
      "location": "q"
    }],
    "code": 400,
    "message": "Invalid Value"
  }
}

Any suggestions for making this more efficient?

2

Been dealing with this for two years in our enterprise file system. The query parameter approach works, but formatting matters. Use ‘folder_id’ in parents instead of passing the folder ID directly. Single quotes around the folder ID are crucial - skip them and you’ll get validation errors every time. Pagination caught me off guard initially. Google Drive API only returns 100 results by default, even with the right query. You need to handle pagination with nextPageToken or you’ll miss files in larger folders. Set a reasonable pageSize too - balances API efficiency with response time.

3

The files.list endpoint with proper query parameters is your best bet. Hit this same bottleneck building a document management system last year. The key is getting the query string right - wrap the folder ID in single quotes like ‘your-folder-id’ in parents. Set your fields parameter to grab everything you need at once: fields=files(id,name,mimeType,modifiedTime,parents,size). This kills that horrible loop through individual file calls. Performance difference was massive - dropped from 15+ seconds to under 2 seconds for folders with 50+ files. Also verify your folder ID is valid - error messages can be misleading when the ID format’s wrong.

4

yep, you gotta check the query syntax. i had a similar issue. try using ‘parentId’ in the parents array, and make sure to url encode everything. that should clear up those validation errors!