Argument cannot be null in Rest Apex class

Question

I am trying to send data from salesforce to external system and have written web service but even after properly encoding every parameter, i am getting argument cannot be null due to which data is not getting sent. Please help me with the possible cause of error.

below is the code snippet:

 @future(Callout=true)    
     public static void makePostCallout2(String first, String last, String em, String conID, String acctID, String utype, String prod, String expDate, String acctOwner, String lmd, String flag, String createdBy, String origin) {

        Http http = new Http();

        HttpRequest request = new HttpRequest();
         request.setEndpoint('***********************');
        request.setMethod('PUT');
       request.setHeader('Content-Type', 'application/x-www-form-urlencode');
        request.setHeader('Authorization', '*****************');
         request.setBody('firstname='+EncodingUtil.urlEncode(first,'UTF-8')+'&lastname='+EncodingUtil.urlEncode(last,'UTF-8')+'&email='+EncodingUtil.urlEncode(em,'UTF-8')+'&contactID='+EncodingUtil.urlEncode(conID,'UTF-8')+'&accountID='+EncodingUtil.urlEncode(acctID,'UTF-8')+'&userType='+EncodingUtil.urlEncode(uType,'UTF-8')+'&product='+EncodingUtil.urlEncode(prod,'UTF-8')+'&expiryDate='+EncodingUtil.urlEncode(expDate,'UTF-8')+'&accountOwner='+EncodingUtil.urlEncode(acctOwner,'UTF-8')+'&lastModifiedDate='+EncodingUtil.urlEncode(lmd,'UTF-8')+'&operation='+EncodingUtil.urlEncode(flag,'UTF-8')+'&createdBy='+EncodingUtil.urlEncode(createdBy,'UTF-8')+'&creationOrigin='+EncodingUtil.urlEncode(origin,'UTF-8'));        
        HttpResponse response = http.send(request);
         system.debug('this is after processing response');
        // Parse the JSON response
        if (response.getStatusCode() != 200) {
            System.debug('The status code returned was not expected: ' +response.getStatusCode() + ' ' + response.getStatus());
        } else {
            System.debug(response.getBody());
        }
    }       

the argument cannot be null is occuring in initializing end point and method in headers.. for privacy reason, endpoint and token has been masked.

Answer 1

You're receiving this error because you're providing null as values for encoding. To better handle these situations, you can either perform sanity checks on your parameters, or introduce some error handling.

An example of sanity checks would be

@future(Callout=true)    
public static void makePostCallout2(String first, String last, String em, String conID, String acctID, String utype, String prod, String expDate, String acctOwner, String lmd, String flag, String createdBy, String origin) {

    if (String.isBlank(first)) {
        //do something with "first"
    }

    if (String.isBlank(last)) {
        //do something with "last"
    }

This isn't the cleanest approach, but has its place. The more recommended approach would be to introduce some basic error handling:

@future(Callout=true)    
public static void makePostCallout2(String first, String last, String em, String conID, String acctID, String utype, String prod, String expDate, String acctOwner, String lmd, String flag, String createdBy, String origin) {
    try {
        Http http = new Http();

        HttpRequest request = new HttpRequest();
        request.setEndpoint('***********************');
        request.setMethod('PUT');
        request.setHeader('Content-Type', 'application/x-www-form-urlencode');
        request.setHeader('Authorization', '*****************');
        request.setBody('firstname='+EncodingUtil.urlEncode(first,'UTF-8')+'&lastname='+EncodingUtil.urlEncode(last,'UTF-8')+'&email='+EncodingUtil.urlEncode(em,'UTF-8')+'&contactID='+EncodingUtil.urlEncode(conID,'UTF-8')+'&accountID='+EncodingUtil.urlEncode(acctID,'UTF-8')+'&userType='+EncodingUtil.urlEncode(uType,'UTF-8')+'&product='+EncodingUtil.urlEncode(prod,'UTF-8')+'&expiryDate='+EncodingUtil.urlEncode(expDate,'UTF-8')+'&accountOwner='+EncodingUtil.urlEncode(acctOwner,'UTF-8')+'&lastModifiedDate='+EncodingUtil.urlEncode(lmd,'UTF-8')+'&operation='+EncodingUtil.urlEncode(flag,'UTF-8')+'&createdBy='+EncodingUtil.urlEncode(createdBy,'UTF-8')+'&creationOrigin='+EncodingUtil.urlEncode(origin,'UTF-8'));        
        HttpResponse response = http.send(request);
        system.debug('this is after processing response');
        // Parse the JSON response
        if (response.getStatusCode() != 200) {
            System.debug('The status code returned was not expected: ' +response.getStatusCode() + ' ' + response.getStatus());
        } else {
            System.debug(response.getBody());
        }
    } catch (IllegalArgumentException iae) {
        //do something with iae
    } catch (Exception e) {
        //do something with e
    }
}

Also, wherever this is being called from, you may also want to check why you're feeding in bad data to begin with.