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FileDownload/CommandButton inside facet of a datatable, not working at all

See original GitHub issue

Describe the bug

In a dataTable I have facets for input and output. In a Blob field, for documents, I render a column with fileupload for input, all working there, and for output I render a commandButton with a fileDownload, no way to make it work.

If I go for the actionListener route to prepare the Stream prior to be called by the filedownload component, it doesnt fire at all the actionlistener. Using process=“@this” makes the actionlistenerr work, but crashes without throwing any error.

If I try to process the blob and create de stream direct in the method called by the filedownload, nothing happens.

This is the relevant sourc excerpt:


                                  <p:column headerText="Documento">
					<p:cellEditor id="conteudo">
						<f:facet name="output">
								<p:commandButton 
									value="Baixar o documento" 
									icon="pi pi-arrow-down" 
									styleClass="ui-button-outlined"
									ajax="false">
									<p:fileDownload value="#{cadastroEventoController.arquivo}"/>
						         </p:commandButton>
						</f:facet>
						<f:facet name="input">
							<p:fileUpload listener="#{cadastroEventoController.trataUploadDeDocumento}" 
							mode="advanced" dragDropSupport="false"
		                                        update="dtDocumentos msgs" sizeLimit="100000000" 
		                                        value="#{cadastroEventoController.arquivo}"
		                                        fileLimit="1" >
		                      
							</p:fileUpload>
						</f:facet>
					</p:cellEditor>
					
				</p:column>

Using ActionListener

<p:commandButton 
	value="Baixar o documento" 
	icon="pi pi-arrow-down" 
	styleClass="ui-button-outlined"
	process="@this"
	actionListener="#{cadastroEventoController.preparaArquivo()}"
	ajax="false">
	<p:fileDownload value="#{cadastroEventoController.arquivo}"/>
</p:commandButton>

Relevant methods:


        // In Case direct use by filedownload 
	public StreamedContent getArquivo() {
		FacesContext context = FacesContext.getCurrentInstance(); 
		Integer linha = context.getApplication().evaluateExpressionGet(context,  "#{linha}",Integer.class); 
		DocumentoEntity doc = eventoDTO.getObjeto().getDocumentos().get(linha); 
		ByteArrayInputStream stream = new ByteArrayInputStream(doc.getConteudo()); 
		return new DefaultStreamedContent(stream, doc.getMime(), doc.getLegenda() + "." + doc.getExtensao());
	}

        // In Case ActionListener works
       	public void preparaArquivo() {
		FacesContext context = FacesContext.getCurrentInstance(); 
		Integer linha = context.getApplication().evaluateExpressionGet(context, "#{linha}",Integer.class); 
		DocumentoEntity doc = eventoDTO.getObjeto().getDocumentos().get(linha);
		ByteArrayInputStream stream = new ByteArrayInputStream(doc.getConteudo());
		setArquivo(new DefaultStreamedContent(stream, doc.getMime(), doc.getLegenda() + "." + doc.getExtensao()));
	}

Extracting the CommandButton from the dataTable, but still inside the form, passing the index, makes any approach works to download the correct blob.

Reproducer

No response

Expected behavior

I would expect the FileDownload, inside a CommandButton, inside a dataTable, to try to get de BLOB contents through the provided attribute and initiate the download. Behavior that works perfectly outside the dataTable.