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(Go) Google Drive - Build a Local Cache of MetadataThis example demonstrates how to download the metadata for all files in a Google Drive account to create a local filesystem cache with the information. The cache can be used to fetch information without having to query Google Drive.
success := true // It requires the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. // This example uses a previously obtained access token having permission for the // Google Drive scope. gAuth := chilkat.NewAuthGoogle() gAuth.SetAccessToken("GOOGLE_DRIVE_ACCESS_TOKEN") rest := chilkat.NewRest() // Connect using TLS. bAutoReconnect := true success = rest.Connect("www.googleapis.com",443,true,bAutoReconnect) // Provide the authentication credentials (i.e. the access token) rest.SetAuthGoogle(gAuth) // ------------------------------------------------------------------- // Initialize our cache object. Indicate the location of the root cache directory, and how many cache levels are to exist. // For small caches (level 0) all cache files are in the root directory. // For medium caches (level 1) cache files are located in 256 sub-directories from the root. // For large caches (level 2) cache files are located in 256x256 sub-directories two levels down from the root. gdCache := chilkat.NewCache() gdCache.SetLevel(0) // Use a root directory that makes sense on your operating system.. gdCache.AddRoot("C:/ckCache/googleDrive") // If we are re-building the cache, we can first delete the entire contents of the cache. numCacheFilesDeleted := gdCache.DeleteAll() // Create a date/time object with an time 7 days from the current date/time. dtExpire := chilkat.NewCkDateTime() dtExpire.SetFromCurrentSystemTime() dtExpire.AddDays(7) // Indicate that we want ALL possible fields. // If no fields are indicated, then only the basic fields are returned. allFields := "appProperties,capabilities,contentHints,createdTime,description,explicitlyTrashed,fileExtension,folderColorRgb,fullFileExtension,headRevisionId,iconLink,id,imageMediaMetadata,isAppAuthorized,kind,lastModifyingUser,md5Checksum,mimeType,modifiedByMeTime,modifiedTime,name,originalFilename,ownedByMe,owners,parents,permissions,properties,quotaBytesUsed,shared,sharedWithMeTime,sharingUser,size,spaces,starred,thumbnailLink,trashed,version,videoMediaMetadata,viewedByMe,viewedByMeTime,viewersCanCopyContent,webContentLink,webViewLink,writersCanShare" // We're going to keep a master list of fileId's as we iterate over all the files in this Google Drive account. // This master list will also be saved to the cache under the key "AllGoogleDriveFileIds". jsonMaster := chilkat.NewJsonObject() jsonMasterArr := jsonMaster.AppendArray("fileIds") // Also keep a list of file paths. jsonMasterPaths := jsonMaster.AppendArray("filePaths") // The default page size is 100, with a max of 1000. rest.AddQueryParam("pageSize","200") json := chilkat.NewJsonObject() // jsonFileMetadata is a JsonObject var i int var numFiles int // Send the request for the 1st page. jsonResponse := rest.FullRequestNoBody("GET","/drive/v3/files") pageNumber := 1 var pageToken *string = new(string) bContinueLoop := rest.LastMethodSuccess() && (rest.ResponseStatusCode() == 200) for bContinueLoop == true { fmt.Println("---- Page ", pageNumber, " ----") json.Load(*jsonResponse) numFiles = json.SizeOfArray("files") i = 0 for i < numFiles { // Add this file ID to the master list. json.SetI(i) jsonMasterArr.AddStringAt(-1,*json.StringOf("files[i].id")) i = i + 1 } // Get the next page of files. // If the "nextPageToken" is present in the JSON response, then use it in the "pageToken" parameter // for the next request. If no "nextPageToken" was present, then this was the last page of files. pageToken = *json.StringOf("nextPageToken") bContinueLoop = false bHasMorePages := json.LastMethodSuccess() if bHasMorePages == true { rest.ClearAllQueryParams() rest.AddQueryParam("pageSize","200") rest.AddQueryParam("pageToken",*pageToken) jsonResponse = *rest.FullRequestNoBody("GET","/drive/v3/files") bContinueLoop = rest.LastMethodSuccess() && (rest.ResponseStatusCode() == 200) pageNumber = pageNumber + 1 } } jsonMasterArr.DisposeJsonArray() // Check to see if the above loop exited with errors... if rest.LastMethodSuccess() != true { fmt.Println(rest.LastErrorText()) gAuth.DisposeAuthGoogle() rest.DisposeRest() gdCache.DisposeCache() dtExpire.DisposeCkDateTime() jsonMaster.DisposeJsonObject() json.DisposeJsonObject() return } // Check to see if the above loop exited with errors... // A successful response will have a status code equal to 200. if rest.ResponseStatusCode() != 200 { fmt.Println("response status code = ", rest.ResponseStatusCode()) fmt.Println("response status text = ", rest.ResponseStatusText()) fmt.Println("response header: ", rest.ResponseHeader()) fmt.Println("response JSON: ", *jsonResponse) gAuth.DisposeAuthGoogle() rest.DisposeRest() gdCache.DisposeCache() dtExpire.DisposeCkDateTime() jsonMaster.DisposeJsonObject() json.DisposeJsonObject() return } // Iterate over the file IDs and download the metadata for each, saving each to the cache... // Also, keep in-memory hash entries of the name and parent[0] so we can quickly // build the path-->fileId cache entries. (Given that the Google Drive REST API uses // fileIds, this gives us an easy way to lookup a fileId based on a filePath.) hashTable := chilkat.NewHashtable() // Set the capacity of the hash table to something reasonable for the number of files // to be hashed. hashTable.ClearWithNewCapacity(521) sbPathForFileId := chilkat.NewStringBuilder() // Used for storing the file name and parents[0] in the hashTable. saFileInfo := chilkat.NewStringArray() saFileInfo.SetUnique(false) var fileId *string = new(string) numFiles = jsonMaster.SizeOfArray("fileIds") i = 0 for i < numFiles { jsonMaster.SetI(i) fileId = *jsonMaster.StringOf("fileIds[i]") sbPathForFileId.SetString("/drive/v3/files/") sbPathForFileId.Append(*fileId) rest.ClearAllQueryParams() rest.AddQueryParam("fields",allFields) jsonResponse = *rest.FullRequestNoBody("GET",*sbPathForFileId.GetAsString()) if (rest.LastMethodSuccess() != true) || (rest.ResponseStatusCode() != 200) { // Force an exit of this loop.. numFiles = 0 } // Save this file's metadata to the local cache. // The lookup key is the fileId. gdCache.SaveTextDt(*fileId,dtExpire,"",*jsonResponse) // Get this file's name and parent[0], and put this information // in our in-memory hashtable to be used below.. json.Load(*jsonResponse) saFileInfo.Clear() saFileInfo.Append(*json.StringOf("name")) saFileInfo.Append(*json.StringOf("parents[0]")) hashTable.AddStr(*fileId,*saFileInfo.Serialize()) fmt.Println(*json.StringOf("name"), ", ", *json.StringOf("parents[0]")) i = i + 1 } // Check to see if the above loop exited with errors... if rest.LastMethodSuccess() != true { fmt.Println(rest.LastErrorText()) gAuth.DisposeAuthGoogle() rest.DisposeRest() gdCache.DisposeCache() dtExpire.DisposeCkDateTime() jsonMaster.DisposeJsonObject() json.DisposeJsonObject() hashTable.DisposeHashtable() sbPathForFileId.DisposeStringBuilder() saFileInfo.DisposeStringArray() return } // Check to see if the above loop exited with errors... // A successful response will have a status code equal to 200. if rest.ResponseStatusCode() != 200 { fmt.Println("response status code = ", rest.ResponseStatusCode()) fmt.Println("response status text = ", rest.ResponseStatusText()) fmt.Println("response header: ", rest.ResponseHeader()) fmt.Println("response JSON: ", *jsonResponse) gAuth.DisposeAuthGoogle() rest.DisposeRest() gdCache.DisposeCache() dtExpire.DisposeCkDateTime() jsonMaster.DisposeJsonObject() json.DisposeJsonObject() hashTable.DisposeHashtable() sbPathForFileId.DisposeStringBuilder() saFileInfo.DisposeStringArray() return } // Now that all the fileId's are in the cache, let's build the directory path // for each fileID. // (Technically, a fileId can have multiple parents, which means it can be in multiple directories // at once. This is only going to build directory paths following the 0'th parent ID in the parents list.) // The directory path for files in "My Drive" will be just the filename. // For files in sub-directories, the path will be relative, such as "subdir1/subdir2/something.pdf" // fmt.Println("---- building paths ----") sbPath := chilkat.NewStringBuilder() numFiles = jsonMaster.SizeOfArray("fileIds") i = 0 for i < numFiles { jsonMaster.SetI(i) sbPath.Clear() fileId = *jsonMaster.StringOf("fileIds[i]") bFinished := false for (bFinished == false) { saFileInfo.Clear() saFileInfo.AppendSerialized(*hashTable.LookupStr(*fileId)) // Append this file or directory name. sbPath.Prepend(*saFileInfo.GetString(0)) // Get the parent fileId fileId = *saFileInfo.GetString(1) // If this fileId is not in the hashtable, then it's the fileId for "My Drive", and we are finished. if hashTable.Contains(*fileId) == false { bFinished = true } else { sbPath.Prepend("/") } } fmt.Println(i, ": ", *sbPath.GetAsString()) // Store the filePath --> fileId mapping in our local cache. fileId = *jsonMaster.StringOf("fileIds[i]") gdCache.SaveTextDt(*sbPath.GetAsString(),dtExpire,"",*fileId) jsonMasterPaths.AddStringAt(-1,*sbPath.GetAsString()) i = i + 1 } jsonMasterPaths.DisposeJsonArray() // Save the master list of file IDs and file paths to the local cache. jsonMaster.SetEmitCompact(false) strJsonMaster := jsonMaster.Emit() gdCache.SaveTextNoExpire("AllGoogleDriveFileIds","",*strJsonMaster) fmt.Println("JSON Master Record:") fmt.Println(*strJsonMaster) // The JSON Master Cache Record looks something like this: // An application can load the JSON master record and iterate over all the files // in Google Drive by file ID, or by path. // { // "fileIds": [ // "0B53Q6OSTWYolQlExSlBQT1phZXM", // "0B53Q6OSTWYolVHRPVkxtYWFtZkk", // "0B53Q6OSTWYolRGZEV3ZGUTZfNFk", // "0B53Q6OSTWYolS2FXSjliMXQxSU0", // "0B53Q6OSTWYolZUhxckMzb0dRMzg", // "0B53Q6OSTWYolbUF6WS1Gei1oalk", // "0B53Q6OSTWYola296ODZUSm5GYU0", // "0B53Q6OSTWYolbTE3c3J5RHBUcHM", // "0B53Q6OSTWYolTmhybWJSUGd5Q2c", // "0B53Q6OSTWYolY2tPU1BnYW02T2c", // "0B53Q6OSTWYolTTBBR2NvUE81Zzg", // ], // "filePaths": [ // "testFolder/abc/123/pigs.json", // "testFolder/starfish20.jpg", // "testFolder/penguins2.jpg", // "testFolder/starfish.jpg", // "testFolder/abc/123/starfish.jpg", // "testFolder/abc/123/penguins.jpg", // "testFolder/abc/123", // "testFolder/abc", // "testFolder/testHello.txt", // "testFolder", // "helloWorld.txt", // ] // } fmt.Println("Entire cache rebuilt...") gAuth.DisposeAuthGoogle() rest.DisposeRest() gdCache.DisposeCache() dtExpire.DisposeCkDateTime() jsonMaster.DisposeJsonObject() json.DisposeJsonObject() hashTable.DisposeHashtable() sbPathForFileId.DisposeStringBuilder() saFileInfo.DisposeStringArray() sbPath.DisposeStringBuilder() |
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