(Lianja) Lower-Level REST API Methods (Google Cloud Storage)

The FullRequest* methods, such as FullRequestBinary, FullRequestMultipart, FullRequestNoBody, FullRequestStream, FullRequestString, etc. are high-level REST API methods that both send the request and receive the response. It is often the case that an application needs make a REST call, but with a finer level of control. The Chilkat REST API provides this feature. An application can break a REST call into the following parts:

1. Send the HTTP request. (via the SendReq* methods)
2. Receive the HTTP response header. (ReadResponseHeader)
3. Receive the HTTP response body. (via the ReadRespBody* methods)

This example demonstrates a REST call using SendReqStringBody, ReadResonseHeader, and ReadRespBodyString.

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// This example demonstrates a REST call using SendReqStringBody, ReadResonseHeader, and ReadRespBodyString.
// It will create a bucket in Google Cloud Storage.

// It requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

loGAuth = createobject("CkAuthGoogle")
// Obtain an access token as shown in one of the following examples:
// See Get Access Token using a Service Account JSON Key
// See Get Access Token using a P12 File

loRest = createobject("CkRest")

// Connect using TLS.
llBAutoReconnect = .T.
llSuccess = loRest.Connect("www.googleapis.com",443,.T.,llBAutoReconnect)

// Provide the authentication credentials (i.e. the access key)
llSuccess = loRest.SetAuthGoogle(loGAuth)

// Build the JSON request body for creating a bucket.
// The only required property is the "name", but we'll add more
// to make a better example..
loJsonReqBody = createobject("CkJsonObject")
llSuccess = loJsonReqBody.AddStringAt(-1,"name","chilkat-bucket-c")
llSuccess = loJsonReqBody.AddStringAt(-1,"kind","storage#bucket")
llSuccess = loJsonReqBody.AddStringAt(-1,"location","US")
llSuccess = loJsonReqBody.AddObjectAt(-1,"versioning")

loPObjVersioning = loJsonReqBody.ObjectOf("versioning")
llSuccess = loPObjVersioning.AddBoolAt(-1,"enabled",.T.)
release loPObjVersioning

// Show the HTTP request body we'll be sending.
? loJsonReqBody.Emit()

// Add the required query parameter.
// See https://cloud.google.com/storage/docs/json_api/v1/buckets/insert
llSuccess = loRest.AddQueryParam("project","chilkattest-1050")

// Add the Content-Type HTTP request header.
llSuccess = loRest.AddHeader("Content-Type","application/json; charset=UTF-8")

// Send the REST HTTP request.
llSuccess = loRest.SendReqStringBody("POST","/storage/v1/b",loJsonReqBody.Emit())
if (llSuccess <> .T.) then
    ? loRest.LastErrorText
    release loGAuth
    release loRest
    release loJsonReqBody
    return
endif

// Read the response header.
lnResponseStatusCode = loRest.ReadResponseHeader()
if (lnResponseStatusCode < 0) then
    // We were unable to receive the response header.
    ? loRest.LastErrorText
    release loGAuth
    release loRest
    release loJsonReqBody
    return
endif

if (lnResponseStatusCode <> 200) then
    // The response was not successful.  We'll still need to receive 
    // the response body, which may contain an error message from the server.
    // If the response has no body, then the method for reading the
    // response body can still be called.  It will simply return with an empty
    // response body.

    // We can examine the response header and status text:
    ? "Response status text: " + loRest.ResponseStatusText
    ? "Response header: " + loRest.ResponseHeader
endif

// Read the response body.  In this case we're expecting it to be JSON..
lcResponseBodyStr = loRest.ReadRespBodyString()
if (loRest.LastMethodSuccess <> .T.) then
    // We were unable to receive the response body.
    // Note: If the response did not include a body (such as for cases where
    // the Content-Length header is 0, or if the response status code implicitly
    // indicates no body, then ReadRespBodyString returns cktrue, and the
    // responseBodyString will be an empty string.
    ? loRest.LastErrorText
    release loGAuth
    release loRest
    release loJsonReqBody
    return
endif

// Show the JSON response.
? "Json Response: " + lcResponseBodyStr


release loGAuth
release loRest
release loJsonReqBody