Can't change picklist-field value in apex

Question

I have to insert a new record that has a field with of type Picklist (Multi Select), and I get this error trying to insert:

TestValue is a value already added in the values list.

bad value for restricted picklist field: TestValue
System.DmlException: Insert failed. First exception on row 0; first error: INVALID_OR_NULL_FOR_RESTRICTED_PICKLIST, bad value for restricted picklist field: TestValue: [Categories__c]
System.DmlException: Insert failed. First exception on row 0; first error: INVALID_OR_NULL_FOR_RESTRICTED_PICKLIST, bad value for restricted picklist field: TestValue: [Categories__c]

The field data type in IDE "Categories__c" is showing String.

I have to run it in a Test Class (@IsTest)

I also found:

Product2.Categories__c.getDescribe().getPicklistValues();

Don't know how I can use it tho.

Thanks in advance.

Answer 1

Mac, looks like you're trying to insert the value TestValue into a field of type picklist. The error really means this:

"TestValue" is not an option available on your picklist.

The easiest thing to do is to just choose a correct value. The method you found will help like this

List<Schema.PicklistEntry> values = Product2.Categories__c.getDescribe().getPicklistValues();
String myValue = '';
if (! values.isEmpty() ) { //this should not happen, but...
  myValue = values[0].getValue();
}
<YourObject>.Categories__c = myValue

If #1 didn't work, make sure that the recordtype your product2 record is under will accept the value you selected. This is something configurable via the GUI

PS: you can always just add "TestValue" to the list of available values in the picklist... but that's likely a horrible idea and you should never add a test value to a prod picklist just to make your tests pass. I am only providing this option here because perhaps your code does not use "TestValue" and instead uses a value that actually should show up in the picklist.