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(Unicode C) Download Binary File to In-Memory BytesThis example demonstrates how to download the binary content of a file from Google Drive directly into local memory.
#include <C_CkAuthGoogleW.h> #include <C_CkRestW.h> #include <C_CkCacheW.h> #include <C_CkStringBuilderW.h> #include <C_CkByteData.h> #include <C_CkFileAccessW.h> void ChilkatSample(void) { BOOL success; HCkAuthGoogleW gAuth; HCkRestW rest; BOOL bAutoReconnect; HCkCacheW gdCache; const wchar_t *fileId; HCkStringBuilderW sbPath; int statusCode; const wchar_t *errResponseBody; HCkByteData jpgBytes; HCkFileAccessW fac; 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 = CkAuthGoogleW_Create(); CkAuthGoogleW_putAccessToken(gAuth,L"GOOGLE-DRIVE-ACCESS-TOKEN"); rest = CkRestW_Create(); // Connect using TLS. // A single REST object, once connected, can be used for many Google Drive REST API calls. // The auto-reconnect indicates that if the already-established HTTPS connection is closed, // then it will be automatically re-established as needed. bAutoReconnect = TRUE; success = CkRestW_Connect(rest,L"www.googleapis.com",443,TRUE,bAutoReconnect); // Provide the authentication credentials (i.e. the access token) CkRestW_SetAuthGoogle(rest,gAuth); // ------------------------------------------------------------------------------ // To download a file, we must know the file ID. // In a previous example (see Build Local Metadata Cache // we built a local cache to make it easy to lookup file IDs given a file path. // Let's say we want to download "testFolder/abc/123/penguins.jpg". // First we lookup the fileId in the cache. With the fileId, we can download the file. gdCache = CkCacheW_Create(); CkCacheW_putLevel(gdCache,0); CkCacheW_AddRoot(gdCache,L"C:/ckCache/googleDrive"); fileId = CkCacheW_fetchText(gdCache,L"testFolder/abc/123/penguins.jpg"); if (CkCacheW_getLastMethodSuccess(gdCache) != TRUE) { wprintf(L"Filepath not found in cache.\n"); CkAuthGoogleW_Dispose(gAuth); CkRestW_Dispose(rest); CkCacheW_Dispose(gdCache); return; } // We need to send a GET request like this: // GET https://www.googleapis.com/drive/v3/files/fileId?alt=media // The fileId is part of the path. sbPath = CkStringBuilderW_Create(); CkStringBuilderW_Append(sbPath,L"/drive/v3/files/"); CkStringBuilderW_Append(sbPath,fileId); CkRestW_AddQueryParam(rest,L"alt",L"media"); // To download to memory, we'll send the request in one call, then receive // the response header, and then the response body. // If the response header indicates failure or an unexpected response, then the // body is not the data we desire. // First send the HTTP request. success = CkRestW_SendReqNoBody(rest,L"GET",CkStringBuilderW_getAsString(sbPath)); if (success != TRUE) { wprintf(L"%s\n",CkRestW_lastErrorText(rest)); CkAuthGoogleW_Dispose(gAuth); CkRestW_Dispose(rest); CkCacheW_Dispose(gdCache); CkStringBuilderW_Dispose(sbPath); return; } // Get the response header. statusCode = CkRestW_ReadResponseHeader(rest); if (statusCode != 200) { wprintf(L"response status code = %d\n",CkRestW_getResponseStatusCode(rest)); wprintf(L"response status text = %s\n",CkRestW_responseStatusText(rest)); wprintf(L"response header: %s\n",CkRestW_responseHeader(rest)); // Read the response body (which should be error text or HTML) errResponseBody = CkRestW_readRespBodyString(rest); if (CkRestW_getLastMethodSuccess(rest) == TRUE) { wprintf(L"response body: %s\n",errResponseBody); } CkAuthGoogleW_Dispose(gAuth); CkRestW_Dispose(rest); CkCacheW_Dispose(gdCache); CkStringBuilderW_Dispose(sbPath); return; } // Read the response body, which should contain the file data. jpgBytes = CkByteData_Create(); success = CkRestW_ReadRespBodyBinary(rest,jpgBytes); if (CkRestW_getLastMethodSuccess(rest) != TRUE) { wprintf(L"%s\n",CkRestW_lastErrorText(rest)); CkAuthGoogleW_Dispose(gAuth); CkRestW_Dispose(rest); CkCacheW_Dispose(gdCache); CkStringBuilderW_Dispose(sbPath); CkByteData_Dispose(jpgBytes); return; } // Save jpgBytes to a file so we can examine the file to verify that it worked. fac = CkFileAccessW_Create(); CkFileAccessW_WriteEntireFile(fac,L"qa_output/penguins_out.jpg",jpgBytes); wprintf(L"File downloaded.\n"); CkAuthGoogleW_Dispose(gAuth); CkRestW_Dispose(rest); CkCacheW_Dispose(gdCache); CkStringBuilderW_Dispose(sbPath); CkByteData_Dispose(jpgBytes); CkFileAccessW_Dispose(fac); } |
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