title: Updating a specific column value in a row inside a datatable from a backing bean based on another column values change
body: <p>I have  a dialog <code>&lt;p:dialog id="vpmopopup"&gt;</code> inside that, I have a form <code>&lt;h:form id="vpmoForm"&gt;</code>,inside that, I have a datatable    <code>&lt;p:dataTable id="reqTypeDtbl"&gt;</code> and inside this datatable, I have an <code>&lt;h:selectOneMenu&gt;</code> and  <code>&lt;h:inputText &gt;</code> in <strong>seperate columns in same row.</strong></p>
  
  <p><br/>
  I need to render the <code>&lt;h:inputText &gt;</code> based on the <code>&lt;h:selectOneMenu&gt;</code> ajax event called where I am setting some values in the backing bean to render the <code>&lt;h:inputText &gt;</code>  in the sepecific row in the datatable.
  <br/>
  I also have an option to add rows and say, when I have added two row, in the seconde row, I am changing the value of the <code>&lt;h:selectOneMenu&gt;</code> where its Ajax method is called which in turn should update the <code>&lt;h:inputText &gt;</code> from the backing bean.
  <br/>
  I tried lot of workaround but nothin seems to work.
  <br/>
  Here is the  workaround I tried 
  <br/>
  Ajax Call in UI :
  <br/></p>
  
  <pre><code>&lt;p:dataTable id="reqTypeDtbl" scrollable="true" scrollHeight="150"
               value="#{systemDetailsBean.vpmoReqDetailslsList}"
               rowIndexVar="index" var="vpmoReqDtlRow"
               rowKey="#{vpmoReqDtlRow.reqTypeName}"&gt;
      &lt;h:selectOneMenu&gt;
          &lt;f:selectItems value="#{systemDetailsBean.vpmoTSSList}" 
                         var="tss" itemLabel="#{tss.label}" itemValue="#{tss.value}" /&gt;
          &lt;p:ajax listener="#{systemDetailsBean.getTssId}"    process="@this"  
                  partialSubmit="true" /&gt;
          &lt;f:param name="rowidno" value="#{index}" required="true" /&gt;
      &lt;/h:selectOneMenu&gt;
  &lt;/p:dataTable&gt;
  </code></pre>
  
  <p><br/>
  Ajax Implementation in Bean :</p>
  
  <pre><code>public void getTssId(AjaxBehaviorEvent evt) {
      Map&lt;String, String&gt; params = FacesContext.getCurrentInstance()
          .getExternalContext().getRequestParameterMap();
  
      int index = Integer.parseInt(params.get("rowidno"));
      String selected = vpmoReqDetailslsList.get(index).getTssReqId();
  
      //I could get the correct rowindex and the selected value using the above code.
      if (selected.equalsIgnoreCase("y")) {
          vpmoEditFlag = false;
          vpmoReqDetailslsList.get(index).setTssReqId("Y");
          System.out.println("Yes  valuve &gt;&gt;" + vpmoReqDetailslsList.get(index).getTssReqId());
  
          RequestContext.getCurrentInstance().update("vpmoForm:reqTypeDtbl:" + index + ":except");
          //I am trying to update the inputtext for the selected row in the datatable from above
      } else {
          vpmoReqDetailslsList.get(index).setTssReqId("N");
          RequestContext.getCurrentInstance().update("vpmoForm:reqTypeDtbl:" + index + ":except");
          //I am trying to update the inputtext for the selected row in the datatable from above
      }
  }
  </code></pre>
  
  <p>The code for rendering  <code>&lt;h:inputText &gt;</code> <br/></p>
  
  <pre><code>&lt;h:inputText value="#{vpmoReqDtlRow.exceptionNum}" id="javax.faces.ViewState"  style="width:100%"
                                  rendered="#{systemDetailsBean.vpmoEditFlag eq  true and  vpmoReqDtlRow.tssReqId eq  'Y'}" /&gt;
  </code></pre>
  
  <p>How can I render the <code>&lt;h:inputText&gt;</code> from the backing bean for a specific row.I mean,  I need to update a specific row which is inside a data table and the data table is inside a form .</p>
  
  <p>The below approach is not working for me</p>
  
  <pre><code>RequestContext.getCurrentInstance().update("vpmoForm:reqTypeDtbl:" + index + ":except");
  </code></pre>
  
  <p><br/>Is there any other option for this to update the only the component inside the datatable which I have highlighted in the screenshot?
  <br/>Any suggestions will be really helpful to resolve this issue.</p>
  
  <p>Adding screen shot for further ref:
  <br/><img src="https://i.stack.imgur.com/NayWQ.jpg" alt="enter image description here"></p>