Question

I am working on the source code of a restaurant POS (Samba pos), and I have 2 problems how the output is formatted when printing a ticket.

The code below collects the tags of products, make headers of them, and sort the products below the header.

Problem 1: I have no influence in the order of headers so the output looks like:

Main course

Steak 22,50

Drinks

Cola 2,00

Starters

Soup 3,50

The right order should be Starters –> Main course –> Desserts –> Drinks
If I could sort the headers alphabetically I would be helped very much. I would change the group tags into: 1 Starters, 2 Maincourse etc etc

Problem 2:

The products are grouped in an earlier stage of the program. Due to choices of the programmer the grouping doesn’t work well for me. I have a long list on the ticket like:

1 x Cola 2,00

2 x Cola 4,00

Is there a way to group products here so that I will have:

3 x cola 6,00

Here is the piece of code:

if (template.GroupTemplate.Contains("{PRODUCT TAG}"))
{
    var groups = lines.GroupBy(GetMenuItemTag);
    var result = new List<string>();
    foreach (var grp in groups)
    {
        var grpSep = template.GroupTemplate.Replace("{PRODUCT TAG}", grp.Key);
        result.AddRange(grpSep.Split(new[] { '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries));
        result.AddRange(grp.SelectMany(x => FormatLines(template, x).Split(new[] { '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries)));
    }
    return result;
}

I have to sort var groups. The problem is that the text {PRODUCT TAG} is replaced with grp.Key within the loop, so ordering var groups before the loop probably won’t work (do I need an extra loop?).

Adding the products to the headers is done on the 3 line of the loop. Is it possible to group items here?

I have dumped the whole file here:
http://pastebin.com/qFr5wN28

Edit:

This piece of code is for producing a ticket on a ticketprinter. A ticket would look like this:

BON
Datum: 2-2-2013
Tijd: 18:35    
Tafel nr.: B22    
Bon nr: 2    
------------------------------------------    
Breakfast    
- 1 Toast and Jam 1,50    
- 1 Egg, Bacon Cheese 3,99    
- 1 Toasted Bagel Cheese 2,25    
- 1 Toasted Bagel Jam 1,50    
- 2 Toast and Jam 1,50    
- 1 Egg, Bacon Cheese 3,99    
- 1 Bacon and Cheese 3,49    
- 1 Bacon and Tomato 3,49    
Deserts    
- 1 Rice Pudding 2,25    
- 1 Fruit Danish 1,50    
Main course    
- 1 Chicken Garden Wrap 5,25    
- 1 Chicken Caesar Wrap 5,75    
- 1 Canadian Wrap 6,99    
- 1 Chicken Greek Wrap 6,99

The headers are tags that I can add to products.
There are several things wrong: the headers above the articles (Deserts, Main Course) appear randomly. I would like to sort them. Not all articles are grouped, for example "toast and jam". If I could sort the headers, I would change the tags a bit. A desired output would be like this:

------------------------------------------    
1 Breakfast    
- 3 Toast and Jam 1,50    
- 2 Egg, Bacon Cheese 3,99    
- 1 Toasted Bagel Cheese 2,25    
- 1 Toasted Bagel Jam 1,50    
- 1 Bacon and Cheese 3,49    
- 1 Bacon and Tomato 3,49    
2 Main course    
- 1 Chicken Garden Wrap 5,25    
- 1 Chicken Caesar Wrap 5,75    
- 1 Canadian Wrap 6,99    
- 1 Chicken Greek Wrap 6,99    
3 Deserts    
- 1 Rice Pudding 2,25    
- 1 Fruit Danish 1,50

Answer 1

You can order your lines using OrderBy like so:

var groups = lines.GroupBy(GetMenuItemTag).OrderBy(l => l.Key);

You also loop through the groups and amend the value of your key. This could be done by adding a Select projection to your group.

var groups = lines.GroupBy(GetMenuItemTag)
                  .Select(l => new { Key = template.GroupTemplate.Replace("{PRODUCT TAG}", grp.Key)
                                   , l.Value } )
                  .OrderBy(l => l.Key);

EDIT:

After thinking about this I realised I was being a little dumb yesterday. I think the following will help you:

//dummy data for testing purposes
List<Tuple<string, string>> items = new List<Tuple<string, string>>();
items.Add(new Tuple<string, string>("Dinner", "steak"));
items.Add(new Tuple<string, string>("Dinner", "chicken"));
items.Add(new Tuple<string, string>("Dinner", "chicken"));
items.Add(new Tuple<string, string>("Desert", "chocolate"));

var groups = (from t in items
             group t by new {Course = t.Item1, Item = t.Item2}
             into grp
                 select new
                 {
                     grp.Key.Course,
                     grp.Key.Item,
                     Quantity = grp.Count()
                 })
             .OrderBy(g => g.Course);

foreach (var g in groups)
          Console.WriteLine(string.Format("{0} {1} {2}", g.Course, g.Item, g.Quantity));

OUTPUT:

Dinner steak 1
Dinner chicken 2
Desert chocolate 1

Obviously you will need to modify the datatypes, etc, but the query itself should give you what you need.