(DataFlex) 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.

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Variant vGAuth
    Handle hoGAuth
    Handle hoRest
    Boolean iBAutoReconnect
    Handle hoJsonReqBody
    Variant vObjVersioning
    Handle hoObjVersioning
    Integer iResponseStatusCode
    String sResponseBodyStr
    String sTemp1
    Boolean bTemp1

    Move False To iSuccess

    // 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.

    Get Create (RefClass(cComChilkatAuthGoogle)) To hoGAuth
    If (Not(IsComObjectCreated(hoGAuth))) Begin
        Send CreateComObject of hoGAuth
    End
    // 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

    Get Create (RefClass(cComChilkatRest)) To hoRest
    If (Not(IsComObjectCreated(hoRest))) Begin
        Send CreateComObject of hoRest
    End

    // Connect using TLS.
    Move True To iBAutoReconnect
    Get ComConnect Of hoRest "www.googleapis.com" 443 True iBAutoReconnect To iSuccess

    // Provide the authentication credentials (i.e. the access key)
    Get pvComObject of hoGAuth to vGAuth
    Get ComSetAuthGoogle Of hoRest vGAuth To iSuccess

    // 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..
    Get Create (RefClass(cComChilkatJsonObject)) To hoJsonReqBody
    If (Not(IsComObjectCreated(hoJsonReqBody))) Begin
        Send CreateComObject of hoJsonReqBody
    End
    Get ComAddStringAt Of hoJsonReqBody -1 "name" "chilkat-bucket-c" To iSuccess
    Get ComAddStringAt Of hoJsonReqBody -1 "kind" "storage#bucket" To iSuccess
    Get ComAddStringAt Of hoJsonReqBody -1 "location" "US" To iSuccess

    Get Create (RefClass(cComChilkatJsonObject)) To hoObjVersioning
    If (Not(IsComObjectCreated(hoObjVersioning))) Begin
        Send CreateComObject of hoObjVersioning
    End
    Get pvComObject of hoObjVersioning to vObjVersioning
    Get ComAppendObject2 Of hoJsonReqBody "versioning" vObjVersioning To iSuccess
    Get ComAddBoolAt Of hoObjVersioning -1 "enabled" True To iSuccess

    // Show the HTTP request body we'll be sending.
    Get ComEmit Of hoJsonReqBody To sTemp1
    Showln sTemp1

    // Add the required query parameter.
    // See https://cloud.google.com/storage/docs/json_api/v1/buckets/insert
    Get ComAddQueryParam Of hoRest "project" "chilkattest-1050" To iSuccess

    // Add the Content-Type HTTP request header.
    Get ComAddHeader Of hoRest "Content-Type" "application/json; charset=UTF-8" To iSuccess

    // Send the REST HTTP request.
    Get ComEmit Of hoJsonReqBody To sTemp1
    Get ComSendReqStringBody Of hoRest "POST" "/storage/v1/b" sTemp1 To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Read the response header.
    Get ComReadResponseHeader Of hoRest To iResponseStatusCode
    If (iResponseStatusCode < 0) Begin
        // We were unable to receive the response header.
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    If (iResponseStatusCode <> 200) Begin
        // 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:
        Get ComResponseStatusText Of hoRest To sTemp1
        Showln "Response status text: " sTemp1
        Get ComResponseHeader Of hoRest To sTemp1
        Showln "Response header: " sTemp1
    End

    // Read the response body.  In this case we're expecting it to be JSON..
    Get ComReadRespBodyString Of hoRest To sResponseBodyStr
    Get ComLastMethodSuccess Of hoRest To bTemp1
    If (bTemp1 <> True) Begin
        // 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.
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Show the JSON response.
    Showln "Json Response: " sResponseBodyStr


End_Procedure