Insert a WHERE clause in a CAML query - using SharePoint, SPServices, JavaScript, and jQuery

Question

I am trying to insert a WHERE clause into my CAML query to filter a date column for NULL (I want to return all rows for which there is no date in Assign Date the column).

This is for a SharePoint List. The code is using the SPServices, jQuery, and JavaScript

I am having quite a time pulling this off - I have very little experience doing this type of integration and less still in using CAML.

This is the CAML query segment of the code:

function loadPrioritizedList() {
    $("#tasksUL").empty();
    $().SPServices({
        operation: "GetListItems",    
        webURL: myURL,
        listName: targetListName,
        CAMLViewFields: "<ViewFields><FieldRef Name='Priority_x0020_Number' /><FieldRef Name='Edit_x0020_Link' /><FieldRef Name='Priority' /><FieldRef Name='Top_x0020_Item_x003f_' /><FieldRef Name='Purpose' /><FieldRef Name='Item_x002d_Task_x0020_Order' /><FieldRef Name='Mode' /><FieldRef Name='Work_x0020_Status' /><FieldRef Name='DueDate' /><FieldRef Name='Task_x0020_Type' /><FieldRef Name='DAK_x0020_Date' /><FieldRef Name='DAK_x0020_No' /><FieldRef Name='AssignedTo' /><FieldRef Name='Money_x0020_Estimate' /><FieldRef Name='ItemStatus' /><FieldRef Name='Assign_x0020_Date' /></ViewFields>",
        CAMLQuery: '<Query>' +
        '<OrderBy>' +
        '<FieldRef Name="Priority_x0020_Number" />' +
        '</OrderBy>' +
        '</Query>', 
        CAMLRowLimit: listrowlimit,  
        completefunc: function (xData, Status) {
            $(xData.responseXML).SPFilterNode("z:row").each(function() {
                var tdHtml = "<tr class='sortable_row' id=" + $(this).attr("ows_ID") + ">";
                tdHtml = tdHtml + "<td style=\"width:60px;\">" + PriorityFormat($(this).attr("ows_Priority_x0020_Number"));  + "</td>";
                tdHtml = tdHtml + '<td style=\"width:49px;\"><a href=\"'+($(this).attr("ows_Edit_x0020_Link")).split(", ")[1] + '\">' + ($(this).attr("ows_Edit_x0020_Link")).split(", ")[1] + '</a></td>';
                tdHtml = tdHtml + "<td style=\"width:83px;\">" + $(this).attr("ows_Priority") + "</td>";
                tdHtml = tdHtml + "<td style=\"width:63px;\">" + TopItem($(this).attr("ows_Top_x0020_Item_x003f_")) + "</td>";
                tdHtml = tdHtml + "<td style=\"width:300px;\">" + StringChk($(this).attr("ows_Purpose")) + "</td>";
                tdHtml = tdHtml + "<td style=\"width:125px;\">" + StringChk($(this).attr("ows_Item_x002d_Task_x0020_Order")) + "</td>";                     
                tdHtml = tdHtml + "<td style=\"width:40px;\">" + StringChk($(this).attr("ows_Mode")) + "</td>";
                tdHtml = tdHtml + "<td style=\"width:75px;\">" + StringChk($(this).attr("ows_Task_x0020_Type")) + "</td>";
                tdHtml = tdHtml + "<td style=\"width:150px;\">" + StringChk($(this).attr("ows_Work_x0020_Status")) + "</td>";
                tdHtml = tdHtml + "<td style=\"width:100px;\">" + FormatDate($(this).attr("ows_DueDate")) + "</td>";
                tdHtml = tdHtml + "<td style=\"width:100px;\">" + FormatDate($(this).attr("ows_DAK_x0020_Date")) + "</td>";
                tdHtml = tdHtml + "<td style=\"width:100px;\">" + StringChk($(this).attr("ows_DAK_x0020_No")) + "</td>";
                tdHtml = tdHtml + "<td style=\"width:300px;\">" + StringChk($(this).attr("ows_AssignedTo")) + "</td>";
                tdHtml = tdHtml + "<td style=\"width:125px;\">" + $(this).attr("ows_Money_x0020_Estimate") + "</td>";
                tdHtml = tdHtml + "<td style=\"width:75px;\">" + StringChk($(this).attr("ows_ItemStatus")) + "</td>";
                tdHtml = tdHtml + "<td style=\"width:100px;\">" + FormatDate($(this).attr("ows_Assign_x0020_Date")) + "</td>";
                tdHtml = tdHtml + "</tr>";
                $("#tasksUL").append(tdHtml);
            });
        }
    });

Any help would be gratefully welcomed, and I thank you in advance.

UPDATE: The latest incarnation of the code is below. I have added the "WHERE" clause as:

"<Where><Eq><FieldRef Name=Assign_x0020_Date' /><Value Type='Date and Time'>IsNull</Value></Eq></Where>" +

But it still returns no results. I'm not sure at this point what I'm missing here.

The query with the above addition looks like this:

function loadPrioritizedList() {
        $("#tasksUL").empty();
        $().SPServices({
            operation: "GetListItems",    
            webURL: myURL,
            listName: targetListName,
            CAMLViewFields: "<ViewFields><FieldRef Name='Priority_x0020_Number' /><FieldRef Name='Edit_x0020_Link' /><FieldRef Name='Priority' /><FieldRef Name='Top_x0020_Item_x003f_' /><FieldRef Name='Purpose' /><FieldRef Name='Item_x002d_Task_x0020_Order' /><FieldRef Name='Mode' /><FieldRef Name='Work_x0020_Status' /><FieldRef Name='DueDate' /><FieldRef Name='Task_x0020_Type' /><FieldRef Name='DAK_x0020_Date' /><FieldRef Name='DAK_x0020_No' /><FieldRef Name='AssignedTo' /><FieldRef Name='Money_x0020_Estimate' /><FieldRef Name='ItemStatus' /><FieldRef Name='Assign_x0020_Date' /></ViewFields>",
            CAMLQuery: '<Query>' +
    "<Where><Eq><FieldRef Name='Assign_x0020_Date' /><Value Type='Date and Time'>IsNull</Value></Eq></Where>" +
            '<OrderBy>' +
            '<FieldRef Name="Priority_x0020_Number" />' +
            '</OrderBy>' +
            '</Query>', 

Answer 1

Since I use my framework I don't really care about the CAML, but it should be something like :

<query>
  <Query>
    <Where>
      <IsNull><FieldRef Name="Assign_x0020_Date"></FieldRef></IsNull>
    </Where>
  </Query>
</query>

BTW you may want to try my framework : http://aymkdn.github.io/SharepointPlus/ The syntax will be (for the same thing) :

function loadPrioritizedList() {
  $("#tasksUL").empty();
  $SP().list(targetListName).get({
    fields:"Priority_x0020_Number,Edit_x0020_Link,Priority,Top_x0020_Item_x003f_,Purpose,Item_x002d_Task_x0020_Order,Mode,Work_x0020_Status,DueDate,Task_x0020_Type,DAK_x0020_Date,DAK_x0020_No,AssignedTo,Money_x0020_Estimate,ItemStatus,Assign_x0020_Date",
    where:"Assign_x0020_Date = ''",
    orderby:"Priority_x0020_Number DESC",
    rowlimit:listrowlimit
  }, function (xData) {
    var tdHTML="";
    for (var i=xData.length; i--;) {
      tdHtml += "<tr class='sortable_row' id=" + xData[i].getAttribute("ID") + ">";
      tdHtml += "<td style=\"width:60px;\">" + PriorityFormat(xData[i].getAttribute("Priority_x0020_Number"));  + "</td>";
      tdHtml += '<td style=\"width:49px;\"><a href=\"'+(xData[i].getAttribute("Edit_x0020_Link")).split(", ")[1] + '\">' + (xData[i].getAttribute("Edit_x0020_Link")).split(", ")[1] + '</a></td>';
      tdHtml += "<td style=\"width:83px;\">" + xData[i].getAttribute("Priority") + "</td>";
      tdHtml += "<td style=\"width:63px;\">" + TopItem(xData[i].getAttribute("Top_x0020_Item_x003f_")) + "</td>";
      tdHtml += "<td style=\"width:300px;\">" + StringChk(xData[i].getAttribute("Purpose")) + "</td>";
      tdHtml += "<td style=\"width:125px;\">" + StringChk(xData[i].getAttribute("Item_x002d_Task_x0020_Order")) + "</td>";                     
      tdHtml += "<td style=\"width:40px;\">" + StringChk(xData[i].getAttribute("Mode")) + "</td>";
      tdHtml += "<td style=\"width:75px;\">" + StringChk(xData[i].getAttribute("Task_x0020_Type")) + "</td>";
      tdHtml += "<td style=\"width:150px;\">" + StringChk(xData[i].getAttribute("Work_x0020_Status")) + "</td>";
      tdHtml += "<td style=\"width:100px;\">" + FormatDate(xData[i].getAttribute("DueDate")) + "</td>";
      tdHtml += "<td style=\"width:100px;\">" + FormatDate(xData[i].getAttribute("DAK_x0020_Date")) + "</td>";
      tdHtml += "<td style=\"width:100px;\">" + StringChk(xData[i].getAttribute("DAK_x0020_No")) + "</td>";
      tdHtml += "<td style=\"width:300px;\">" + StringChk(xData[i].getAttribute("AssignedTo")) + "</td>";
      tdHtml += "<td style=\"width:125px;\">" + xData[i].getAttribute("Money_x0020_Estimate") + "</td>";
      tdHtml += "<td style=\"width:75px;\">" + StringChk(xData[i].getAttribute("ItemStatus")) + "</td>";
      tdHtml += "<td style=\"width:100px;\">" + FormatDate(xData[i].getAttribute("Assign_x0020_Date")) + "</td>";
      tdHtml += "</tr>";
    }
    $("#tasksUL").append(tdHtml);
  }
});

Answer 2

Ah, the answer was in the way the IsNull has to be used. I modified the code:

"<Where><Eq><FieldRef Name=Assign_x0020_Date' /><Value Type='Date and Time'>IsNull</Value></Eq></Where>" +

To:

"<Where><IsNull><FieldRef Name=Assign_x0020_Date' /></IsNull></Where>" +

Thanks to this SO post: https://stackoverflow.com/a/1341301/2190871