Serializing large CSV file

[frer]

Hello,

I would like to serialize a large object tree to a csv without busting my memory.

My object tree is a map that contains approximately 1,000,000 objects.  Today, I iterate through the object tree and stock everything in a StringBuffer.  I then send this buffer content to my JSF page:

<ui:composition xmlns="http://www.w3.org/1999/xhtml"
                xmlns:s="http://jboss.com/products/seam/taglib"
                xmlns:ui="http://java.sun.com/jsf/facelets"
                xmlns:f="http://java.sun.com/jsf/core"
                xmlns:h="http://java.sun.com/jsf/html"
                xmlns:rich="http://richfaces.org/rich"
                xmlns:a="http://richfaces.org/a4j"> 
    <h:messages styleClass="message" infoClass="success" errorClass="error" warnClass="warning"/>

    <f:view contentType="text/csv">#{reportTemplateAction.reportContent}</f:view>
</ui:composition>

Obviously this is causing me to have twice the representation of the object in memory at once and causing me memory issues.

Is there any way I can serialize this with JSF and seam while iterating through it?

Thanks

[niox.nikospara.yahoo.com]

Hello,

I have done something similar: A link that generates a file, then serves its content to the client. In other words a standard download link. NOTE: my use case does not submit the form. The data is gathered in a wizard and after finishing it, the user is provided with a link to download the generated document. Your code seems to contain a messages component, so it may be different use case. Anyway, here is how:

First you need a link that calls an action:

<s:link value="..." action="#{generationBean.download}" />

In the action method:

@Name("generationBean")
@AutoCreate
@Scope(EVENT)
public class GenerationBean {
     ...
     public void download() {
          ...
          // watch out if it may run in portal!!!
          HttpServletResponse response = (HttpServletResponse) FacesContext.getCurrentInstance().getExternalContext().getResponse();
          response.setContentType(...as appropriate...);
          response.addHeader("Content-disposition", "attachment; filename=\"THE FILENAME HERE\"");

          try {
               ServletOutputStream os = response.getOutputStream();
               os.write(...data...); // ITERATE OVER YOUR STRUCTURE AND WRITE DATA, A PIECE AT A TIME
               // OR GIVE THE ServletOutputStream TO ANYTHING THAT WRITES TO STREAMS
               os.flush();
               os.close();
               FacesContext.getCurrentInstance().responseComplete(); // DONT FORGET THIS ONE
          }
          catch(IOException ioe) {
               ...
          }
     }
     ...
}

The browser sees the content type and acts accordingly. The JSF mechanism obeys the responseComplete() command and does not execute the render response phase.

[frer]

Awesome.  Exactly what I was looking for.

Thanks

[frer]

Works well but the only thing is that the attachment is not downloadable but inserted directly in browser.  I would like to have a popup where the user chooses to save or open the attachement.  My code is the following:

            HttpServletResponse response = (HttpServletResponse) FacesContext.getCurrentInstance().getExternalContext().getResponse();
            response.setContentType("text/csv");
            response.addHeader("Content-disposition", "attachment; filename=\"" + fileName + "\"");
             
            if(reportTemplate.getIsDaily()) {
                facadeLocator.getReportTemplateGeneratorDailyFacade().generateCSVReport(reportTemplate, response.getOutputStream());
            } else {
                facadeLocator.getReportTemplateGeneratorHourlyFacade().generateCSVReport(reportTemplate, response.getOutputStream());
            }
            response.getOutputStream().flush();
            response.getOutputStream().close();
            FacesContext.getCurrentInstance().responseComplete()

where the content is generated by my methods.

How can I force the attachment (even though I have set it in the header)?

Thanks

Francois

[clerum]

It's a function of the clients browser.

IF you want it downloaded then response.setContentType(application/octet-stream);

Otherwise specify the correct mime type (text/csv) and if clients browser can handle the type then it will be loaded in the browser.

[frer]

Thanks Cody.

Actually the problem was even simpler.  I was using a a4j:commandButton for my download link.  By using a h:commandButton it solved my problem and now works flawlessly.

Thanks again to both of you.