Correct usage of Google Drive API v3 to retrieve the folder parent(s) Id of a file?

Question

SCENARIO

---

I'm trying to develop a simple program using the Google Drive API v3, that must be able to list all the files stored in the user's "drive", and then interpret the directory hierarchy (this means: determine in what folder(s) name/id the file is stored).

PROBLEM

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The problem I have is that basicaly the File.Parents property (which in theory contains the ID of the folder(s) on where the file is stored) is always empty (nul) after I receive the response, even when I ensured to specify the parents value in the request:

Code written in C#:

using Google.Apis.Drive.v3;

private DriveService client;
// ...

FilesResource.ListRequest request = this.client.Files.List();

request.PageSize = 100;
request.SupportsTeamDrives = false;
request.Fields = "nextPageToken, files(id, name, description, size,
                                       trashed, shared, ownedByMe, isAppAuthorized,
                                       createdTime, modifiedTime, 
                                       parents)";

FileList response = await request.ExecuteAsync();

Original code written in VB.NET:

Imports Google.Apis.Drive.v3

Private client As DriveService
' ...

Dim request As FilesResource.ListRequest = Me.client.Files.List()
With request
    .PageSize = 100
    .SupportsTeamDrives = False
    .Fields = "nextPageToken, files(id, name, description, size,
                                    trashed, shared, ownedByMe, isAppAuthorized,
                                    createdTime, modifiedTime, 
                                    parents)"
End With

Dim response As FileList = Await request.ExecuteAsync()

Also, and aditionally, other properties like File.CreatedTime and File.ModifiedTime are nul too, I don't understand why. Other properties like File.Id or File.Name works as expected... fine.

QUESTION

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Why the File.Parents property is nul, and how do I fix it?. What I'm missing to do?.

RESEARCH

---

Files: list

File metadata:

{
  "kind": "drive#file",
  "id": string,
  "name": string,
  "mimeType": string,
  "description": string,
  "starred": boolean,
  "trashed": boolean,
  "explicitlyTrashed": boolean,
  "trashingUser": {
    "kind": "drive#user",
    "displayName": string,
    "photoLink": string,
    "me": boolean,
    "permissionId": string,
    "emailAddress": string
  },
  "trashedTime": datetime,
  "parents": [
    string
  ],
  "properties": {
    (key): string
  },
  "appProperties": {
    (key): string
  },
  "spaces": [
    string
  ],
  "version": long,
  "webContentLink": string,
  "webViewLink": string,
  "iconLink": string,
  "hasThumbnail": boolean,
  "thumbnailLink": string,
  "thumbnailVersion": long,
  "viewedByMe": boolean,
  "viewedByMeTime": datetime,
  "createdTime": datetime,
  "modifiedTime": datetime,
  "modifiedByMeTime": datetime,
  "modifiedByMe": boolean,
  "sharedWithMeTime": datetime,
  "sharingUser": {
    "kind": "drive#user",
    "displayName": string,
    "photoLink": string,
    "me": boolean,
    "permissionId": string,
    "emailAddress": string
  },
  "owners": [
    {
      "kind": "drive#user",
      "displayName": string,
      "photoLink": string,
      "me": boolean,
      "permissionId": string,
      "emailAddress": string
    }
  ],
  "teamDriveId": string,
  "lastModifyingUser": {
    "kind": "drive#user",
    "displayName": string,
    "photoLink": string,
    "me": boolean,
    "permissionId": string,
    "emailAddress": string
  },
  "shared": boolean,
  "ownedByMe": boolean,
  "capabilities": {
    "canAddChildren": boolean,
    "canChangeViewersCanCopyContent": boolean,
    "canComment": boolean,
    "canCopy": boolean,
    "canDelete": boolean,
    "canDownload": boolean,
    "canEdit": boolean,
    "canListChildren": boolean,
    "canMoveItemIntoTeamDrive": boolean,
    "canMoveTeamDriveItem": boolean,
    "canReadRevisions": boolean,
    "canReadTeamDrive": boolean,
    "canRemoveChildren": boolean,
    "canRename": boolean,
    "canShare": boolean,
    "canTrash": boolean,
    "canUntrash": boolean
  },
  "viewersCanCopyContent": boolean,
  "writersCanShare": boolean,
  "permissions": [
    permissions Resource
  ],
  "hasAugmentedPermissions": boolean,
  "folderColorRgb": string,
  "originalFilename": string,
  "fullFileExtension": string,
  "fileExtension": string,
  "md5Checksum": string,
  "size": long,
  "quotaBytesUsed": long,
  "headRevisionId": string,
  "contentHints": {
    "thumbnail": {
      "image": bytes,
      "mimeType": string
    },
    "indexableText": string
  },
  "imageMediaMetadata": {
    "width": integer,
    "height": integer,
    "rotation": integer,
    "location": {
      "latitude": double,
      "longitude": double,
      "altitude": double
    },
    "time": string,
    "cameraMake": string,
    "cameraModel": string,
    "exposureTime": float,
    "aperture": float,
    "flashUsed": boolean,
    "focalLength": float,
    "isoSpeed": integer,
    "meteringMode": string,
    "sensor": string,
    "exposureMode": string,
    "colorSpace": string,
    "whiteBalance": string,
    "exposureBias": float,
    "maxApertureValue": float,
    "subjectDistance": integer,
    "lens": string
  },
  "videoMediaMetadata": {
    "width": integer,
    "height": integer,
    "durationMillis": long
  },
  "isAppAuthorized": boolean
}

Answer 1

Try setting fields=* and work backwards from there. The wildcard is alluded to at https://developers.google.com/drive/v3/web/performance#partial, although that page looks generally out of date.