Test Error & Trigger Null Pointer Exception

Question

I'm attempting to build a trigger that pulls the FullPhotoUrl from the User profile and set a field (FullPhotoUrl__c) on the SFDC_Employee__c object to the url. Here's the error I'm getting I'll paste the code underneath it.

System.NullPointerException: Attempt to de-reference a null object Trigger.EmployeeProfileImageHandler: line 16, column 1

trigger EmployeeProfileImageHandler on SFDC_Employee__c (before update) {
SFDC_Employee__c[] employees = (SFDC_Employee__c[])Trigger.new;

Set<String> employeelist = new Set<String>();
for (SFDC_Employee__c employee : employees) {
    employeelist.add(employee.User_ID__c);
}

User[] photos = [Select Name, FullPhotoUrl From User where ID IN :employeelist];
Map<String, User> photomap = new Map<String, User>();
for (User photo : photos) {
    photomap.put(photo.Name,photo);
}

for (SFDC_Employee__c employee : employees) {
    employee.FullPhotoUrl__c = photomap.get(employee.Name).FullPhotoUrl;
   }
}

I'm also getting an error on the test class which I've never run into

System.DmlException: Insert failed. First exception on row 0; first error: MIXED_DML_OPERATION, DML operation on setup object is not permitted after you have updated a non-setup object (or vice versa): SFDC_Employee__c, original object: UserRole: []

Here's the test class code.

@IsTest
public class EmployeeProfileTest {
@TestSetup
static void TestEmployeeProfile() {
    UserRole r = new UserRole(DeveloperName = 'MyCustomRole', Name = 'My Role');
    insert r;

    Profile profileId = [SELECT Id FROM Profile WHERE Name = 'Standard User' LIMIT 1];

    User u = new User();
    u.FirstName = 'Test';
    u.LastName = 'UserLastName';
    u.ProfileId = profileId.Id;
    u.Email = '[email protected]';
    u.Username = '[email protected]' + System.currentTimeMillis();
    u.CompanyName = 'TEST';
    u.Title = 'title';
    u.Alias = 'alias';
    u.TimeZoneSidKey = 'America/Los_Angeles';
    u.EmailEncodingKey = 'UTF-8';
    u.LanguageLocaleKey = 'en_US';
    u.LocaleSidKey = 'en_US';
    u.UserRoleId = r.Id;
    insert u;       

    SFDC_Employee__c e = new SFDC_Employee__c();
    e.Name = 'Test UserLastName';
    e.Employee_User__c = u.Id;
    e.User_ID__c = u.Id;
    insert e;


    }
@IsTest
static void methodTest() {
    Test.startTest();
    Test.stopTest();
    }
}

Answer 1

You are getting exception here photomap.get(employee.Name) if your map doesn't contains the key then it gives you null as return and you are referring field value from it. So you need to put a null check here.

for (SFDC_Employee__c employee : employees) {
     if(photomap.containskey(employee.Name))
         employee.FullPhotoUrl__c = photomap.get(employee.Name).FullPhotoUrl;
   }
}

for your second operation Mixed DMl its related to DML operations on certain sObjects, sometimes referred to as setup objects, can’t be mixed with DML on other sObjects in the same transaction. This restriction exists because some sObjects affect the user’s access to records in the org. You must insert or update these types of sObjects in a different transaction to prevent operations from happening with incorrect access-level permissions. For example, you can’t update an account and a user role in a single transaction.

Mixed DML in Test class

Here are some workarounds to avoid this.

Answer 2

Well your null pointer exception is because in your photomap you are using the key as photo.name (here - photomap.put(photo.Name,photo);) and then you are trying to access a value from this map by passing it a key of employee.Name (here - photomap.get(employee.Name).FullPhotoUrl;) which does not exist in the map and hence you get a null pointer exception when you try to access the FullPhotoUrl field. Your map key should be of same type and should exist in the map in order to access it.

If I think what your trying to achieve is to get the FullPhotoUrl for each employee then you should try this -

trigger EmployeeProfileImageHandler on SFDC_Employee__c (before update) {
SFDC_Employee__c[] employees = (SFDC_Employee__c[])Trigger.new;

Set<String> employeelist = new Set<String>();

for (SFDC_Employee__c employee : employees) {
        employeelist.add(employee.User_ID__c);
    }

User[] photos = [Select Name, FullPhotoUrl From User where ID IN :employeelist];
Map<String, User> photomap = new Map<String, User>();
for (User photo : photos) {
    photomap.put(photo.Name,photo);
}

for (SFDC_Employee__c employee : employees) {
    for (User photo : photos) {
        if(photo.Id==employee.User_Id__c){
            if(photomap.containsKey(photo.Name)){
                employee.FullPhotoUrl__c = photomap.get(photo.Name).FullPhotoUrl;
            }
        }
    }
}

Here I am matching to check if the User Id is same for the employee as well as the User (photo) (ie. the both records belong to the same User) and then if the value exists in the map or not, otherwise I would still get the null pointer exception if the value did not exist in the map. And after that we assign the value.

I would also suggest to change the map key to photo.Id as it will always be unique and is a better practise then using a name field.

Lastly, your second question already has an answer here.