p:commandButton with p:fileDownload and no ajax only works in second click

问题

I'm using JSF 2.0, Primefaces 3.4.2, Spring 3.1.2.

I'm facing a similar problem of the guy of this link: h:commandButton works from the second click.

Like him I'm not using ajax in the <p:commandButton> but I'm using a <p:fileDownload /> inside the button tag.

I have two views: "list.xhtml" and "downloadView.xhtml". In myBean.java I send a DataModel from view "list.xhtml" to view "downloadView.xhtml" as a request attribute as shown in the code below:

FacesUtil.getServletContext().setAttribute("myDataModelFromRequest", this.myDataModel);

The bean is anotted with @Scope("view")

In view "downloadView.xhtml" I populated succesfully a dataTable with the DataModel sent from request. But the problem happens when I click in the button to download the file. It only works on second try. I already tried to change the return of my method from null to "downloadView" but the problem was not solved.

In debug mode I noticed that only enter in the "downloadMethod()" on second click.

Anyone have an idea to solve it?

myBean.java

public String viewListMethod() {
    //some work here...

    FacesUtil.getServletContext().setAttribute("myDataModelFromRequest", this.myDataModel);

    return "downloadView";
}

downloadView.xhtml

<h:form id="formId" prependId="false">
    <p:dataTable
        id="dataTableId" var="myVar" value="#{myDataModelFromRequest}"                  
        selection="#{cargaProcessoControlador.myArray}" 
        paginator="true" rows="10" paginatorPosition="bottom" paginatorAlwaysVisible="false">
            <f:facet name="header">  
                    bla bla bla
            </f:facet>

            <p:column selectionMode="multiple" style="width:18px" />

            //collumns here...                      
    </p:dataTable>


    <p:commandButton id="btDownload" ajax="false" value="Download" icon="ui-icon-document" >
        <p:fileDownload value="#{myBean.downloadMethod()}" />
    </p:commandButton>
</h:form>

回答1:

The scope "view" on spring doesn´t exist... So you created your own, right? Just to check... I had that kind of problem once, and I think it was something to do with validation... the immediate=true attribute solved my problem.

回答2:

This is something to do with the scope of the page. Your problem is due to partial rendering of page. Initially when you load the page it is not getting loaded fully and because of that the button is not part of that particular view when you try to click on the button for the first time. Try to make you view proper or explicitly render the page from the backing bean before displaying the page

来源：https://stackoverflow.com/questions/13878620/pcommandbutton-with-pfiledownload-and-no-ajax-only-works-in-second-click

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