SharePoint 2013: How to update multi-value lookup field using JavaScript CSOM

Question

I have a Contacts list which has a multi-value lookup field called ContactType. The result of a CAML query will show the following value for ContactType for one of the list items:

1;#Applicant;#2;#Employee

I had a look at Fiddler after executing a CSOM query against the multi-value lookup field and noticed that the SP.FieldLookupValue object has two properties with the values:

$1E_1 : 1
$2e_1 : "Applicant"

However when you save a value you can only set the lookupId which is 1 in this case. There is no method to set up the value as in lookup.set_lookupValue().

I am attempting to copy the contents of ContactType into a new list item of Contacts. Unfortunately I have no success when updating the ContactType field. This is what I've tried so far:

var clientContext = new SP.ClientContext.get_current(); 
var oList = clientContext.get_web().get_lists().getByTitle('Contacts');
var itemCreateInfo = new SP.ListItemCreationInformation();
var oListItem = oList.addItem(itemCreateInfo);

var contactTypes = new Array();

$.each(contact.contactTypes, function (index, contactType) {
    var lookup = new SP.FieldLookupValue();
    lookup.set_lookupId(contactType.id);
    contactTypes.push(lookup);
});

// other set_item statements skipped for brevity
oListItem.set_item('ContactType', contactTypes);

oListItem.update();

The error message is:

Invalid lookup value. A lookup field contains invalid data.

I also experimented with the following code without any success:

lookup.set_lookupId(contactType.id + ";#" + contactType.title);

In this case the error message is:

The input string is not in the correct format.

If I update a single lookup I have no problems but the issue lies in the saving of the array of lookups. For example, the following code works fine:

var lookup = new SP.FieldLookupValue();
lookup.set_lookupId(1);
contactTypes.push(lookup);
oListItem.set_item('ContactType', lookup);

but it doesn't play ball when attempting to save the array of lookups as in

oListItem.set_item('ContactType', contactTypes);

Any ideas?

Answer 1

Instead of creating a SP.FieldLookupValue(), you can store the contents in a string. You can then try directly setting the lookup column as a string like so:

var lookupString = "1;#Applicant;#2;#Employee";
oListItem.set_item('ContactType', lookupString);

Answer 2

You can use following code, if you have Multiple Value LookUp Field and want to add listitem with all selected LookUp Field. Following code will add 3 lookUp Field value whose id is 1,2 and 3.

allBUValues=[1,2,3];

var lookupVals = [];

for(i=0;i<allBUValues.length;i++)
{
    var lookupVal = new SP.FieldLookupValue();
    lookupVal.set_lookupId(allBUValues[i]);
    lookupVals.push(lookupVal);
}

aListItem.set_item('BusinessUnit', lookupVals); 

aListItem.update();

Answer 3

You might want to have a look at this post: Add values to lookupmulti field in c#

Since you are working with a multi-value lookup you should set the value of it with type SPFieldLookupValueCollection.

Powershell and JavaScript Code/Objects are often very similar in SharePoint.

Here is a post from R Manimaran with some more detail of it: https://rmanimaran.wordpress.com/2012/07/16/update-lookup-field-using-client-object-model/