Using Javascript to Manipulate a List Form Field

Using Javascript to Manipulate a List Form Field

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Hi, my name is Rob Howard, and I’m a Program Manager with the SharePoint Designer team. Like several of the other people posting here, I also built many of the Application Templates for Windows SharePoint Services.

If you’re familiar with them, you may have noticed that in several of the application templates we use a bit of Javascript to set default form values based on the query string. Because we found this to be useful in many different cases throughout our applications, I wanted to share our method with you guys so that you can include it in the applications you develop.

When might you use this?

It’s pretty easy to set a field’s default value through the list settings in the browser UI, so why might you need Javascript to set a default field value? The reason is that field default values can only take static values or simple formulae based on the current user or today’s date. If that meets your needs, then I’d definitely recommend sticking with that method. Sometimes, though, you may want the form to fill with default values based on the user’s interaction with the previous page, and that’s exactly where this method comes in.

How does it work?

In short, we add some Javascript to the page that runs when the body is loaded. This Javascript parses the page’s query string, locates the HTML objects that are rendered by the relevant SharePoint fields, and sets their value based on the information in the query string.

getTagFromIdentifierAndTitle

The most important part of our solution is the “getTagFromIdentifier” function. This function finds the HTML element rendered by a given SharePoint FormField control. It takes the following parameters:

  • tagName – The name of the tag rendered in the form’s HTML
  • identifier – The string associated with the SharePoint type of the relevant field
  • title – The value of the relevant HTML tag’s “title” attribute, which also matches the field’s display name

Here’s a partial table of SharePoint column types and their corresponding “identifiers” and “tagNames”:

SharePoint Field Type identifier tagName
Single Line of Text TextField input
Multiple Lines of Text TextField input
Number TextField input
Currency TextField input
Choice (dropdown) DropDownChoice select
Lookup (single)* Lookup select
Lookup (multiple) SelectCandidate; SelectResult select
Yes/No BooleanField input

*Lookups are a bit more complicated because Lookup FormFields render differently when the target list contains more than 20 items. See the end of the post for an example.

function getTagFromIdentifierAndTitle(tagName, identifier, title) {

  var len = identifier.length;

  var tags = document.getElementsByTagName(tagName);

  for (var i=0; i < tags.length; i++) {

    var tempString = tags[i].id;

    if (tags[i].title == title && (identifier == "" || tempString.indexOf(identifier) == tempString.length - len)) {

      return tags[i];

    }

  }

  return null;

}

fillDefaultValues

Now that we have the HTML elements that we want to set, we need the values with which to set them. In our solution, we wrote the “fillDefaultValues” function, which parses the page’s querystring and then uses the values to set the field defaults.

function fillDefaultValues() {

  var qs = location.search.substring(1, location.search.length);

  var args = qs.split("&");

  var vals = new Object();

  for (var i=0; i < args.length; i++) {

    var nameVal = args[i].split("=");

    var temp = unescape(nameVal[1]).split('+');

    nameVal[1] = temp.join(' ');

    vals[nameVal[0]] = nameVal[1];

  } 

  // Set HTML element default values here

}

_spBodyOnLoadFunctionNames

In most cases SharePoint pages are based on a master page that contains the “body” element. These content pages can’t directly add a function to the body’s onload event. In order to work around this limitation, SharePoint provides the “_spBodyOnLoadFunctionNames” array. When the body is loaded, the onload event handler executes each function whose name is contained in this array. We added “fillDefaultValues” to the array so that it would run when the body’s onload event fires.

_spBodyOnLoadFunctionNames.push("fillDefaultValues");

All Together Now

With the script above, you can set most different field types to any value from the querystring – or any other source that javascript can access. Below is a full example of the script we use to set the default value of a Lookup field based on an ID stored in the querystring. You’ll notice that setting a Lookup field is a bit more complicated than some other field types. The reason is that Lookup FormFields are rendered with different HTML when the target list contains more than 20 items.

Enjoy!

<script type="text/javascript">

 

// This javascript sets the default value of a lookup field identified

// by <<FIELD DISPLAY NAME>> to the value stored in the querysting variable

// identified by <<QUERYSTRING VARIABLE NAME>>

 

 

// Customize this javascript by replacing <<FIELD DISPLAY NAME>> and

// <<QUERYSTRING VARIABLE NAME>> with appropriate values.

// Then just paste it into NewForm.aspx inside PlaceHolderMain

 

_spBodyOnLoadFunctionNames.push("fillDefaultValues");

 

function fillDefaultValues() {

  var qs = location.search.substring(1, location.search.length);

  var args = qs.split("&");

  var vals = new Object();

  for (var i=0; i < args.length; i++) {

    var nameVal = args[i].split("=");

    var temp = unescape(nameVal[1]).split('+');

    nameVal[1] = temp.join(' ');

    vals[nameVal[0]] = nameVal[1];

  } 

  setLookupFromFieldName("<<FIELD DISPLAY NAME>>", vals["<<QUERYSTRING VARIABLE NAME>>"]);

}

 

function setLookupFromFieldName(fieldName, value) {

  if (value == undefined) return;

  var theSelect = getTagFromIdentifierAndTitle("select","Lookup",fieldName);

 

// if theSelect is null, it means that the target list has more than

// 20 items, and the Lookup is being rendered with an input element

 

  if (theSelect == null) {

    var theInput = getTagFromIdentifierAndTitle("input","",fieldName);

    ShowDropdown(theInput.id); //this function is provided by SharePoint

    var opt=document.getElementById(theInput.opt);

    setSelectedOption(opt, value);

    OptLoseFocus(opt); //this function is provided by SharePoint

  } else {

    setSelectedOption(theSelect, value);

  }

}

 

function setSelectedOption(select, value) {

  var opts = select.options;

  var l = opts.length;

  if (select == null) return;

  for (var i=0; i < l; i++) {

    if (opts[i].value == value) {

      select.selectedIndex = i;

      return true;

    }

  }

  return false;

}

 

function getTagFromIdentifierAndTitle(tagName, identifier, title) {

  var len = identifier.length;

  var tags = document.getElementsByTagName(tagName);

  for (var i=0; i < tags.length; i++) {

    var tempString = tags[i].id;

    if (tags[i].title == title && (identifier == "" || tempString.indexOf(identifier) == tempString.length - len)) {

      return tags[i];

    }

  }

  return null;

}

</script>

  • Great post! Exactly what I need in a lot of my activities.

  • Die Leute aus dem SharePoint-Designer-Blog haben einen Artikel veröffentlicht, wie Formularfelder mit Hilfe von Javascript manipuliert werden können. Nützlich kann dies bswp. bei Vorauswahlen von Lookup-Fields sein ... Original Artikel (Verfasst

  • Das SharePoint Designer Team beschreibt in einem Artikel , wei man mit Hilfe von JavaScript die Inhalte

  • Thanks for this. It's great to see how you guys are doing it. We have been doing something similar since the Team Services days but I still gleaned a few good ideas from your code (especially in the genericizing aspects). One thing I have been stuck on is how to set one of the new People fields to the Current User by default. Would love to hear if you guys are doing this or have any ideas.

    Cheers!

  • This works great!  Now I need help with pre-loading a Business Data lookup field.  It is a combination of a textarea and some other hidden inputs.  HELP!!!!! please :)

  • I'm trying to to do something similar were on the same form one field's data is dependant on another field and both these field are lookup fields,  it will be great If you can tell me the names of the application templates using this feature, so that I can take a look how its works.

  • Thanks! I used this code, just modified a bit - to meet my needs... works well!

  • The following blog entry is a cross-posting from the SharePoint Designer Team Blog . It has received

  • Aha ... A post on what I was looking for.

  • Yes but how do you get this script onto a wiki creation page?

  • Siguiendo con la recopilación de recursos iniciada en un post previo , en la nueva entrega de recursos

  • One small sugestion. If you test for "theInput != null" you will not get an exception, if the sscript did not find a control:

    function setLookupFromFieldName(fieldName, value) {

     if (value == undefined) return;

     var theSelect = getTagFromIdentifierAndTitle("select","Lookup",fieldName);

    // if theSelect is null, it means that the target list has more than

    // 20 items, and the Lookup is being rendered with an input element

     if (theSelect == null) {

       var theInput = getTagFromIdentifierAndTitle("input","",fieldName);

       if (theInput == null)

       {

         return;

       }

       ShowDropdown(theInput.id); //this function is provided by SharePoint

       var opt=document.getElementById(theInput.opt);

       setSelectedOption(opt, value);

       OptLoseFocus(opt); //this function is provided by SharePoint

     } else {

       setSelectedOption(theSelect, value);

     }

    }

    René

  • Is it possible to get this (or something similar) to work on a Sharepoint 2003 site? It'd be hugely useful for a few projects I'm working on and I can't get the server updated just yet.

  • This is great-

     A coworker of mine came up with a similar method to locate the input field's ID in V2 and now in V3-

    I have posted much of it here:

    http://bermingham.blogspot.com/2007/07/finding-sharepoint-fields-using.html

  • Hi Rob,

    You're script is working like a charm on the lookup fields. I even found the application template where you used it and found out you used a content editor web part on the newform.aspx so you can edit the javascript directly from sharepoint. Beautiful. I'm not very good with java script and i'm trying to set the default values for two text fields (Single line of text). I've been struggling with your example for one week straight, where it probably takes you 1 minute.

    Can you maybe give an example where two fields (Single line of text) are filled by default. Or maybe just explain what i have to specify in your example where you state (// Set HTML element default values here).

    I really hope you can help me out.....

    Thanks, Marc

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