sharepoint Adding selections to a multivalue lookup field


Example

This example assumes that your lookup column is named MultiLookupColumnName and that you want to set your multi-lookup field to lookup to the items with IDs 1 and 2.

Using jQuery AJAX

2010
var listName = "YourListName";
var lookupList = "LookupListName";
var idOfItemToUpdate = 1;
var url = "/server/site/_vti_bin/ListData.svc/"+listName+"("+idOfItemToUpdate+")"; 
var data = JSON.stringify({
    MultiLookupColumnName:[
        {__metadata:{uri:"http://yoursiteurl/_vti_bin/ListData.svc/"+lookupList+"(1)"}},
        {__metadata:{uri:"http://yoursiteurl/_vti_bin/ListData.svc/"+lookupList+"(2)"}}
    ]
});
$.ajax({
    method: 'POST',
    url: url,
    contentType: 'application/json',
    headers: {
      "X-HTTP-Method" : "MERGE",
      "If-Match" : "*"
    },
    data: data
});
2013
var listGuid = "id-of-list-to-update"; // use list GUID here
var lookupGuid = "id-of-lookup-list"; // use lookup list GUID here
var idOfItemToUpdate = 1;
var url = "/server/site/_api/lists('"+ listGuid + "')/items("+ idOfItemToUpdate + ")";
var data = JSON.stringify({
    MultiLookupColumnName:[
        {__metadata:{uri:"http://yoursiteurl/_api/lists('" + lookupGuid + "')/items(1)"}},
        {__metadata:{uri:"http://yoursiteurl/_api/lists('" + lookupGuid + "')/items(2)"}}
    ]
});
$.ajax({
    method: 'POST',
    url: url,
    contentType: 'application/json',
    headers: {
      "X-HTTP-Method" : "MERGE",
      "If-Match" : "*"
    },
    data: data
});

Using XMLHttpRequest

2010
var listName = "YourListName";
var lookupList = "LookupListName";
var idOfItemToUpdate = 1;
var url = "/server/site/_vti_bin/ListData.svc/YourListName("+idOfItemToUpdate+")";
var data = JSON.stringify({
    MultiLookupColumnName:[
       {__metadata:{uri:"http://yoursiteurl/_vti_bin/ListData.svc/"+lookupList+"(1)"}},
        {__metadata:{uri:"http://yoursiteurl/_vti_bin/ListData.svc/"+lookupList+"(2)"}}
    ]
});
var xhr = new XMLHttpRequest();
xhr.open("POST",url,true);
xhr.setRequestHeader("X-HTTP-Method", "MERGE");
xhr.setRequestHeader("If-Match", "*");
xhr.setRequestHeader("Content-Type","application/json");
xhr.send(data);
2013
var listGuid = "id-of-list-to-update";
var lookupGuid = "id-of-lookup-list";
var idOfItemToUpdate = 1;
var url = "/server/site/_api/lists('"+ listGuid + "')/items("+ idOfItemToUpdate + ")"; 
var data = JSON.stringify({
    MultiLookupColumnName:[
        {__metadata:{uri:"http://yoursiteurl/_api/lists('" + lookupGuid + "')/items(1)"}},
        {__metadata:{uri:"http://yoursiteurl/_api/lists('" + lookupGuid + "')/items(2)"}}
    ]
});
var xhr = new XMLHttpRequest();
xhr.open("POST",url,true);
xhr.setRequestHeader("X-HTTP-Method", "MERGE");
xhr.setRequestHeader("If-Match", "*");
xhr.setRequestHeader("Content-Type","application/json");
xhr.send(data);