Workshop 201, Tutorial 3, Step 4.3, Apex

InvoiceUtilities.cls

public class InvoiceUtilities {

    // class method to renumber Line Items for a given Invoice number
    // returns a string that indicates success or failure
    public static String renumberLineItems(String invoiceName) {

    // create a copy of the target Invoice object and it's Line Items
    Invoice__c invoice = [Select i.Name, (Select Name From Line_Items__r ORDER BY Name) 
                            From Invoice__c i 
                           Where i.Name = :invoiceName LIMIT 1];

    // loop through each Line Item, renumbering as you go
    Integer i = 1;
    for (Line_Item__c item : invoice.Line_Items__r) {
      item.Name = String.valueOf(i);
      System.debug(item.Name);
      i++;
    }

    // update the Line Items in one transaction, rollback if any problems
    // and return error messages to the calling environment
    try {
      database.update(invoice.Line_Items__r);
    }
    catch (DmlException e) {
      return e.getMessage();
    }

    // on success, return a message to the calling program
    return 'Line items renumbered successfully.'; 
  }
}

i couldn't get this to give back any records until i changed the SELECT statement to use "LIKE" as in:
Invoice__c invoice = [Select i.Name, (Select Name From Line_Items__r ORDER BY Name)
From Invoice__c i
Where i.Name LIKE :invoiceName LIMIT 1];
However, then the input parameter had to change to use % instead of - so the "INV-0004" had to become "INV%0004" and that messed up the rest of the workbook exercises.
DId anyone else have this trouble? How did you solve it?

I'm having issues with the reference to the Arrays in the app. invoice.Line_Items__r does not work at all. I double check if the Object had some misspelling or something but it doesn't. Can't reference the Line Items per invoice :(

@cindynor I had the same trouble. Here is my solution:

List<Invoice__c> invoices =     
            [Select i.Name,(Select Name From Line_Items__r ORDER BY Name)
            From Invoice__c i
            Where i.Name =  'INV–0004'];//It work (dash copied from Debug Log from Developer Console) 
        //                  'INV-0004'];//It doesn't work (dash typed from keyboard or copied from sample code)
        //  look at the different length of dashes

Dash from Debug Dev Console you can get in this way:

List<Invoice__c> invoices =     
            [Select i.Name,(Select Name From Line_Items__r ORDER BY Name)
            From Invoice__c i ];
for (Invoice__c invoice : invoices) {
        System.debug(invoice.Name);
        }

My code executed pretty ok. I noticed after the execution however that my "Invoice Number" field format is without the dash so that's INV0004 for me.

thanks rafal00785 I have also noted your approach.

Hi Faced same issue..Here is my solution.
My code executed.I just copied the Invoice number from Record and used in code. The dash length is same as developer console.

String s = InvoiceUtilities.renumberLineItems('INV–0011');

Srilaxmi15 is correct, copy and paste the invoice number from the application; for some reason it's a different dash. In the workbook, they use U+2013, En Dash, instead of what's in the record, a simple U+002D, Hyphen Minus sign.