Dynamics crm 2011 n to n lookup

N:N lookup in Dynamics CRM 2011.

For to 4.0 version: http://dynamicslollipops.blogspot.com/2011/07/mscrm-40-nn-lookup-field.html

Prerequest customization:
1) 1:N relation, and lookup placed on the form.
2) N:N relationship for holding the values.

Walkthrough:

1) Create new javascript webresource with the following code:

var CRM_FORM_TYPE_CREATE = 1;

RetreiveAssociatedEntities = function(relationshipSchemaName, entity1SchemaName, entity1KeyValue, retreiveAttribute) {
    var fetchXml = "<fetch mapping='logical'>"
    + "  <entity name='" + relationshipSchemaName + "'>"
    + "    <all-attributes />"
    + "    <filter>"
    + "      <condition attribute='" + entity1SchemaName + "id' operator='eq' value ='" + entity1KeyValue + "' />"
    + "    </filter>"
    + "  </entity>"
    + "</fetch>";

    var fetchResults = Fetch(fetchXml);

    var nodeList = fetchResults.selectNodes("resultset/result");

    var returnList = new Array();
    if (nodeList == null || nodeList.length == 0) {
        return returnList;
    } else {
        for (i = 0; i < nodeList.length; i++) {
            var idValue = nodeList[i].selectSingleNode('./' + retreiveAttribute).nodeTypedValue;
            returnList[i] = idValue;
        }
        return returnList;
    }
}
MischiefMayhemSOAP = function(serviceUrl, xmlSoapBody, soapActionHeader, suppressError) {
    var xmlReq = "<?xml version='1.0' encoding='utf-8'?>"
    + "<soap:Envelope xmlns:soap='http://schemas.xmlsoap.org/soap/envelope/'"
    + "  xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'"
    + "  xmlns:xsd='http://www.w3.org/2001/XMLSchema'>"
    + GenerateAuthenticationHeader()
    + "  <soap:Body>"
    + xmlSoapBody
    + "  </soap:Body>"
    + "</soap:Envelope>";

    var httpObj = new ActiveXObject("Msxml2.XMLHTTP");

    httpObj.open("POST", serviceUrl, false);

    httpObj.setRequestHeader("SOAPAction", soapActionHeader);
    httpObj.setRequestHeader("Content-Type", "text/xml; charset=utf-8");
    httpObj.setRequestHeader("Content-Length", xmlReq.length);

    httpObj.send(xmlReq);

    var resultXml = httpObj.responseXML;

    var errorCount = resultXml.selectNodes("//error").length;
    if (errorCount != 0) {
        var msg = resultXml.selectSingleNode("//description").nodeTypedValue;

        if (typeof (suppressError) == "undefined" || suppressError == null) {
            alert("The following error was encountered: " + msg);
        }

        return null;
    } else {
        return resultXml;
    }
}

Fetch = function(fetchXml) {
    var xmlSoapBody = "<Fetch xmlns='http://schemas.microsoft.com/crm/2007/WebServices'>"
    + "  <fetchXml>"
    + FetchEncode(fetchXml)
    + "  </fetchXml>"
    + "</Fetch>";

    var fetchResponse = MischiefMayhemSOAP("/MSCRMServices/2007/CrmService.asmx", xmlSoapBody, "http://schemas.microsoft.com/crm/2007/WebServices/Fetch");

    if (fetchResponse != null) {
        var fetchResults = new ActiveXObject("Msxml2.DOMDocument");

        fetchResults.async = false;
        fetchResults.resolveExternals = false;
        fetchResults.loadXML(fetchResponse.text);

        return fetchResults;
    } else {
        return null;
    }
}
FetchEncode = function(strInput) //_HtmlEncode
{
    var c;
    var HtmlEncode = '';

    if (strInput == null) {
        return null;
    }
    if (strInput == '') {
        return '';
    }

    for (var cnt = 0; cnt < strInput.length; cnt++) {
        c = strInput.charCodeAt(cnt);

        if (((c > 96) && (c < 123)) ||
  ((c > 64) && (c < 91)) ||
  (c == 32) ||
  ((c > 47) && (c < 58)) ||
  (c == 46) ||
  (c == 44) ||
  (c == 45) ||
  (c == 95)) {
            HtmlEncode = HtmlEncode + String.fromCharCode(c);
        }
        else {
            HtmlEncode = HtmlEncode + '&#' + c + ';';
        }
    }

    return HtmlEncode;
}

AssociateEntities = function(moniker1name, moniker1id, moniker2name, moniker2id, RelationshipName) {
    var authenticationHeader = GenerateAuthenticationHeader();
    // Prepare the SOAP message.
    var xml = "<?xml version='1.0' encoding='utf-8'?>";
    xml += "<soap:Envelope xmlns:soap='http://schemas.xmlsoap.org/soap/envelope/' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance\' xmlns:xsd='http://www.w3.org/2001/XMLSchema\'>";
    xml += authenticationHeader;
    xml += "<soap:Body><Execute xmlns='http://schemas.microsoft.com/crm/2007/WebServices'><Request xsi:type='AssociateEntitiesRequest'>";
    xml += "<Moniker1><Id xmlns='http://schemas.microsoft.com/crm/2006/CoreTypes'>" + moniker1id + "</Id>";
    xml += "<Name xmlns='http://schemas.microsoft.com/crm/2006/CoreTypes'>" + moniker1name + "</Name></Moniker1>";
    xml += "<Moniker2><Id xmlns='http://schemas.microsoft.com/crm/2006/CoreTypes'>" + moniker2id + "</Id>";
    xml += "<Name xmlns='http://schemas.microsoft.com/crm/2006/CoreTypes'>" + moniker2name + "</Name></Moniker2>";
    xml += "<RelationshipName>" + RelationshipName + "</RelationshipName>";
    xml += "</Request></Execute></soap:Body></soap:Envelope>";

    // Prepare the xmlHttpObject and send the request.
    var xHReq = new ActiveXObject("Msxml2.XMLHTTP");
    xHReq.Open("POST", "/mscrmservices/2007/CrmService.asmx", false);
    xHReq.setRequestHeader("SOAPAction", "http://schemas.microsoft.com/crm/2007/WebServices/Execute");
    xHReq.setRequestHeader("Content-Type", "text/xml; charset=utf-8");
    xHReq.setRequestHeader("Content-Length", xml.length);
    xHReq.send(xml);

    // Capture the result.
    var resultXml = xHReq.responseXML;

    // Check for errors.
    var errorCount = resultXml.selectNodes('//error').length;

    if (errorCount != 0) {
        var msg = resultXml.selectSingleNode('//description').nodeTypedValue;
        alert(msg);
    }
}

DisassociateEntities = function(moniker1name, moniker1id, moniker2name, moniker2id, RelationshipName) {
    var authenticationHeader = GenerateAuthenticationHeader();
    // Prepare the SOAP message.
    var xml = "<?xml version='1.0' encoding='utf-8'?>";
    xml += "<soap:Envelope xmlns:soap='http://schemas.xmlsoap.org/soap/envelope/' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance\' xmlns:xsd='http://www.w3.org/2001/XMLSchema\'>";
    xml += authenticationHeader;
    xml += "<soap:Body><Execute xmlns='http://schemas.microsoft.com/crm/2007/WebServices'><Request xsi:type='DisassociateEntitiesRequest'>";
    xml += "<Moniker1><Id xmlns='http://schemas.microsoft.com/crm/2006/CoreTypes'>" + moniker1id + "</Id>";
    xml += "<Name xmlns='http://schemas.microsoft.com/crm/2006/CoreTypes'>" + moniker1name + "</Name></Moniker1>";
    xml += "<Moniker2><Id xmlns='http://schemas.microsoft.com/crm/2006/CoreTypes'>" + moniker2id + "</Id>";
    xml += "<Name xmlns='http://schemas.microsoft.com/crm/2006/CoreTypes'>" + moniker2name + "</Name></Moniker2>";
    xml += "<RelationshipName>" + RelationshipName + "</RelationshipName>";
    xml += "</Request></Execute></soap:Body></soap:Envelope>";

    // Prepare the xmlHttpObject and send the request.
    var xHReq = new ActiveXObject("Msxml2.XMLHTTP");
    xHReq.Open("POST", "/mscrmservices/2007/CrmService.asmx", false);
    xHReq.setRequestHeader("SOAPAction", "http://schemas.microsoft.com/crm/2007/WebServices/Execute");
    xHReq.setRequestHeader("Content-Type", "text/xml; charset=utf-8");
    xHReq.setRequestHeader("Content-Length", xml.length);
    xHReq.send(xml);

    // Capture the result.
    var resultXml = xHReq.responseXML;

    // Check for errors.
    var errorCount = resultXml.selectNodes('//error').length;

    if (errorCount != 0) {
        var msg = resultXml.selectSingleNode('//description').nodeTypedValue;
        alert(msg);
    }
}

//returns the item location in array if not found -1
GetIndexFromArray = function(item, recordArr) {
    for (var i = 0; i < recordArr.length; i++) {
        if (recordArr[i] != null && recordArr[i].id == item) {
            return i;
        }
    }
    return -1;
}

/*"new_new_entity1_new_entity2new","new_multynewid", "new_entity2", "new_name"*/
FillMultiLookup = function(relationshipSchemaName, lookupSchemaName, relatedEntitySchemaName, relatedEntityPrimaryAttributeSchemaName) {
    var relatedValues = RetreiveAssociatedEntities(relationshipSchemaName, Xrm.Page.data.entity.getEntityName(), Xrm.Page.data.entity.getId(), relatedEntitySchemaName + "id");
    var value = new Array();
    for (var i = 0; i < relatedValues.length; i++) {
        value[i] = new Object();
        value[i].id = relatedValues[i];
        value[i].name = RetreiveAssociatedEntities(relatedEntitySchemaName, relatedEntitySchemaName, relatedValues[i], relatedEntityPrimaryAttributeSchemaName)[0];
        value[i].typename = relatedEntitySchemaName;
    }
 crmForm.all[lookupSchemaName].DataValue = value;
}

UpdateN2N = function(nnId, relatedEntitySchemaName, relatedEntitySchemaId, lookupSchemaName) {
    var oldValues = RetreiveAssociatedEntities(nnId, Xrm.Page.data.entity.getEntityName(), Xrm.Page.data.entity.getId(), relatedEntitySchemaId);
 var value = crmForm.all[lookupSchemaName].DataValue;
    //if there's records in lookup
    if (value != null) {
        //go over all the related records and remove them if not in the new list (lookup)
        var temp = value;
        for (var i = 0; i < oldValues.length; i++) {
            //if not in the new list disassociate them
            var index = GetIndexFromArray(oldValues[i], temp);
            if (index == -1) {
                DisassociateEntities(Xrm.Page.data.entity.getEntityName(), Xrm.Page.data.entity.getId(), relatedEntitySchemaName, oldValues[i], nnId);
            }
            else { // if in the list remove them from the list
                temp[index] = null;
            }
        } //ends for
        //go over all the remaining records and associate them
        for (var i = 0; i < temp.length; i++) {
            if (temp[i] != null) {
                AssociateEntities(Xrm.Page.data.entity.getEntityName(), Xrm.Page.data.entity.getId(), relatedEntitySchemaName, temp[i].id, nnId);
            }
        }
    }
    else if (oldValues != null) {
        for (var i = 0; i < oldValues.length; i++) {
            DisassociateEntities(Xrm.Page.data.entity.getEntityName(), Xrm.Page.data.entity.getId(), relatedEntitySchemaName, oldValues[i], nnId);
        }
    }
}

FilterN2NLookup = function(filterByLookup, filterLookup, entityName, nnName, nnFrom, linkedEntityName, linkedAttributeName) {
    var filter = '';
    var values = filterByLookup.DataValue;
    if (values != null) {
        //filter = '<filters><filter entity="' + entityName + '"><condition attribute="' + attributeName + '" operator="in">';
        //for (var i = 0; i < values.length; i++) {
        //    filter += '<value uiname="' + values[i].name + '">' + values[i].id + '</value>';
        // }
        //filter += '</condition></filter></filters>';

        filter = '<link-entity entity="' + entityName + '" name="' + nnName + '" from="' + nnFrom + '" to="' + nnFrom + '" visible="false" intersect="true"><link-entity name="' + linkedEntityName + '" from="' + linkedAttributeName + '" to="' + linkedAttributeName + '"><filter type="and"><condition attribute="' + linkedAttributeName + '" operator="in">';
        for (var i = 0; i < values.length; i++) {
            filter += '<value uiname="' + values[i].name + '">' + values[i].id + '</value>';
        }
        filter += '</condition></filter></link-entity></link-entity>';

    }
    filterLookup.AddParam('filters', filter);
}

/*"new_new_entity1_new_entity2new","new_multynewid", "new_entity2", "new_name"*/
function ConvertN2N(relationshipSchemaName, lookupSchemaName, relatedEntitySchemaName, relatedEntityPrimaryAttributeSchemaName)
{
 document.getElementById(lookupSchemaName).setAttribute("lookupstyle", "multi");
 document.getElementById(lookupSchemaName).setAttribute("_lookupstyle", "multi");

 document.getElementById(lookupSchemaName).onchange = function(){UpdateN2N(relationshipSchemaName, relatedEntitySchemaName, relatedEntitySchemaName + "id", lookupSchemaName)};

 Xrm.Page.getAttribute(lookupSchemaName).setSubmitMode("never");

 if (crmForm.FormType != CRM_FORM_TYPE_CREATE) {
  FillMultiLookup(relationshipSchemaName, lookupSchemaName, relatedEntitySchemaName, relatedEntityPrimaryAttributeSchemaName);
 }
 else {
  Xrm.Page.getControl(lookupSchemaName).setDisabled(true);
 }
}

2) Add it to the form

3) Add to the onload 

   3.1) Function: ConvertN2N

   3.2) Parameters: N:N Relationship name, lookup attribute name, Related Entity Schema Name, Related Entity Primary Attribute Schema Name

(Example: "new_incident_new_problem", "new_problemid", "new_problem", "new_name")

That's it, everything else is inside the code. 

Plug and Play.