(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.

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 vPObjVersioning
    Handle hoPObjVersioning
    Integer iResponseStatusCode
    String sResponseBodyStr
    String sTemp1
    Boolean bTemp1

    // 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 ComAddObjectAt Of hoJsonReqBody -1 "versioning" To iSuccess

    Get ComObjectOf Of hoJsonReqBody "versioning" To vPObjVersioning
    If (IsComObject(vPObjVersioning)) Begin
        Get Create (RefClass(cComChilkatJsonObject)) To hoPObjVersioning
        Set pvComObject Of hoPObjVersioning To vPObjVersioning
    End
    Get ComAddBoolAt Of hoPObjVersioning -1 "enabled" True To iSuccess
    Send Destroy of hoPObjVersioning

    // 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 <> True) 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