I need help guys.

First of all is it possible to call data from a URL web service and insert that back into a record from a trigger? If not how do I go about getting a single field from a web service and inserting it into a custom object record?

This what I have at the moment. I have data coming through the API which is where I get my merged fields from. Then I want this URL to return me a field called district which I then want inserting back into the record that has just ran the trigger.

Nothing happening although the code is being accepted. Any thoughts here? DO I need to upsert, update? SOmeone mentioned to me that I need the ID of the incident__c but if the trigger has just been launch form a specific record on Incident__c why would I need to do that? If I do need to do it what am I querying?

trigger LatLong on Incident__c (before update) {

    // Pass in the URL for the request  
    
    // For the purposes of this sample,assume that the URL  
    
    // returns the XML shown above in the response body  
    
    public void parseResponseDom(String url){
        Http h = new Http();
        HttpRequest req = new HttpRequest();
        // url that returns the XML in the response body  
    
        req.setEndpoint('http://www.uk-postcodes.com/latlng/{!latitude__c}.{!longitude__c}.xml');
        req.setMethod('GET');
        HttpResponse res = h.send(req);
        Dom.Document doc = res.getBodyDocument();
        
        //Retrieve the root element for this document.  
    
        Dom.XMLNode result = doc.getRootElement();
        
        String district = result.getChildElement('district', null).getText();
        // print out specific elements  
        
        System.debug('district: ' + district);

        for(Dom.XMLNode child : result.getChildElements()) {

        System.debug(child.getText());

        }
        
        Incident__c I = [select ID from Incident__c 
             ];
             
        I.Council_Name_Text__c = district;
       
        update I;
        
  
        }
    }