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    #1

    Problem with error handling of custom DataSource executeDownload.

    I am using SmartGWTPower 2.4 and Firefox 4.0.1, I have to implement to download a file related to a record in a ListGrid.
    I set a field type to "binary" but there was no download icon in the ListGrid, so I added an IButton to the Layout.
    The download works fine, but there is a problem with the error handling. I used the same error handling in the catch clause as in core DS operations (executeFetch, executeAdd, executeUpdate, executeRemove) and a popup appeared with the error message. In case of executeDownload, the former screen disappeared and the following page appeared:

    Code:
    <HTML>
<BODY ONLOAD='var results = document.formResults.results.value;parent.isc.Comm.hiddenFrameReply(2,results)'><BR><BR><BR><BR><BR><BR><BR><BR><BR><BR><BR><BR><BR><BR><BR><BR><BR><BR><FORM name='formResults'><TEXTAREA readonly name='results'>
//isc_RPCResponseStart-->[{queueStatus:-1,isDSResponse:true,invalidateCache:false,status:-1,data:"My Error Message"}]//isc_RPCResponseEnd</TEXTAREA></FORM>
</BODY></HTML>
    ds.xml:
    Code:
    <DataSource ID="myCustomDS" serverConstructor="my.app.server.ds.MyCustomDataSource">
 <fields>
   <field name="docid" hidden="true" primaryKey="true" type="text"/>
    <field name="filename" type="text"/>
    <field name="fileData" type="binary"/>
    client:
    Code:
    downloadButton.addClickHandler(new ClickHandler() {
 public void onClick(ClickEvent event) {
   DSRequest requestProperties = new DSRequest();
   String filename = myListGrid.getSelectedRecord().getAttributeAsString("filename");
   requestProperties.setOperationId(filename);
   myCustomDS.downloadFile(myListGrid.getSelectedRecord(), "fileData", requestProperties);
 }
});
    server:
    Code:
    public DSResponse executeDownload(DSRequest req) throws Exception {
  String attachedFile = req.getDownloadFieldName();
  String attachedFileName = req.getOperationId();
  DSResponse resp = new DSResponse();
  resp.setDropExtraFields(true);
  try {
    ...
    req.setDownloadFileName(attachedFileName);
    Map responseMap = new HashMap();
    responseMap.put(attachedFile + "_filename", attachedFileName);
    responseMap.put(attachedFile + "_filesize", fileData.length);
    responseMap.put(attachedFile, new ByteArrayInputStream(fileData));
    resp.setData(responseMap);
    resp.setDataSource(req.getDataSource());
  } catch (Exception e) {
    req.setDownloadFieldName(null);
    resp = new DSResponse("My error message", DSResponse.STATUS_FAILURE);
  }
  return resp;
}
    server log:
    Code:
    INFO: ===  INFO 2011.06.24 14:36:10 (Logger.java:388) - URL: '/MyProject/myproject/sc/IDACall', User-Agent: 'Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0.1) Gecko/20100101 Firefox/4.0.1': Moz (Gecko) with Accept-Encoding header

INFO: === DEBUG 2011.06.24 14:36:10 (Logger.java:406) - Parsed XML from (in memory stream): 2ms

INFO: === DEBUG 2011.06.24 14:36:10 (Logger.java:406) - Processing 1 requests.

INFO: === DEBUG 2011.06.24 14:36:10 (Logger.java:406) - Request #1 (DSRequest) payload: {
   criteria:{
       docid:"12345",
       download_fieldname:"fileData"
   },
   operationConfig:{
       dataSource:"myCustomDS",
       operationType:"downloadFile"
   },
   appID:"builtinApplication",
   operation:"mydoc.pdf",
   oldValues:{
       docid:"12345",
       download_fieldname:"fileData"
   }
}

INFO: ===  INFO 2011.06.24 14:36:10 (Logger.java:388) - Performing 1 operation(s)

INFO: === DEBUG 2011.06.24 14:36:10 (Logger.java:406) - [builtinApplication.mydoc.pdf] No userTypes defined, allowing anyone access to all operations for this application

INFO: === DEBUG 2011.06.24 14:36:10 (Logger.java:406) - [builtinApplication.mydoc.pdf] No public zero-argument method named '_mydoc.pdf' found, performing generic datasource operation

INFO: === DEBUG 2011.06.24 14:36:10 (Logger.java:406) - Content type for RPC transaction: text/html; charset=UTF-8

INFO: === DEBUG 2011.06.24 14:36:10 (Logger.java:406) - non-DMI response, dropExtraFields: true

INFO: ===  INFO 2011.06.24 14:36:10 (Logger.java:388) - /MyProject/myproject/sc/IDACall: 417 -> 266 bytes
    Please help me, to resolve this problem.
    Tags: None
    #2
    Error handling for downloads is not done the normal way (due to browser limitations). If there's a possibility of a recoverable error during a download, do a request *before* the download to check for errors, then start the download.

    Comment

      #3
      I have managed to implement this download task with error handling with RPC. I would like to ask, as it can be implemented with RPCResponse why not with DSResponse?

      client:
      Code:
      downloadButtonRPC.addClickHandler(new ClickHandler() {
  public void onClick(ClickEvent event) {
    String filename = myListGrid.getSelectedRecord().getAttributeAsString("filename");
    String docid = myListGrid.getSelectedRecord().getAttributeAsString("docid");
    RPCRequest req = new RPCRequest();
    req.setDownloadResult(true);
    req.setActionURL("documentServlet?filename=" + filename + "&docid=" + docid);
    RPCManager.sendRequest(req);
  }
});
      server:
      Code:
      protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  String filename = request.getParameter("filename");
  String docid = request.getParameter("docid");
  String errMsg = null;
  byte[] fileData = null;
  ServletOutputStream os = null;
  try {
    .. 
    response.setContentType("application/pdf");
    response.setHeader("Content-Disposition", "attachment;filename=" + filename);
    os = response.getOutputStream();
    os.write(fileData);
    os.flush();
  } catch (Exception e) {
    errMsg = "My error message";
  } finally {
    try {
      if (os != null) os.close();
    } catch (IOException e) {}
  }
  if (errMsg != null) {
    response.setHeader("Content-Disposition", "");
    try {
      RPCManager rpc = new RPCManager(request, response);
      rpc.sendFailure((RPCRequest) rpc.getRequests().get(0), errMsg);
    } catch (Exception e) {}
  }
}

      Comment

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