Trigger on acc deletion if one of two criterias is true [duplicate]

Question

I am new to triggers, and I have tried creating a trigger to prevent deleting account if :

1. a string field Ninja_store_ID is NOT blank
2. a Boolean field (check box ) is not checked (False)

The trigger I created below is preventing the deletion but not checking either of the criterias, because we want to allow the acc deletion if one of the criterias is false.

so if the string field is blank allow deletion OR if the boolean field is TRUE, allow deletion

Here is the demo trigger:

trigger Demo on account(before delete){ 
     for(Account acc: Trigger.old){ 
         if(Acc.deleted__c != true && Acc.Ninja_Store_Id__c != '' ){ 
             acc.AddError('not able to delete'); 
        } 
    } 
}

Answer 1

I think your trigger is pretty close to what you're looking for, you just don't have the correct conditions in your if statement.

Right now, your code says "prevent deletion (by adding an error) when deleted__c is false and Ninja_Store_Id__c is not an empty string"

An empty string is not the same as blank. Salesforce doesn't store completely empty strings '' in SObject records (except, and instead converts the value to null. null != '').

Salesforce gives us String.isBlank() and String.isNotBlank() to handle such situations.

Also, <boolean value> == true can be reduced to simply <boolean value>. Likewise, <boolean value> != true can be reduced to !<boolean value>.

So given what you've told us, your if statement should be
if(!acc.deleted__c && String.isNotBlank(acc.Ninja_Store_Id__c))

Running through the various possible scenarios, writing down what they are and what result they give (not what you want to happen, what actually does happen given the code you have) can be a helpful tool. If I were to do that, this is what that would look like:

• deleted__c == true
  • then the first condition is false. false && anything = false, so we don't need to evaluate the other condition
  • don't enter the if block.
  • Deletion is allowed
• deleted__c == false, Ninja Store is blank.
  • we satisfy the first condition
  • Ninja Store is blank, so the second condition results in false
  • true && false = false, so we don't enter the if block
  • Deletion is allowed
• deleted__c == false, Ninja Store has a value
  • Both conditions are satisfied, and we enter the if block
  • Deletion is not allowed