Sort a list and all its nested objects using LINQ

Question

There is an organisation with several departments and each department has a few employees.

I have created the following object model:

public class Organisation
{
    public int Code { get; set; }
    public string Type { get; set; }
    public string Name { get; set; }
    public List<Department> Departments { get; set; }
}

public class Department
{
    public int Code { get; set; }
    public string Name { get; set; }
    public List<Employee> Employees { get; set; }
}

public class Employee
{
    public int Code { get; set; }
    public string Name { get; set; }
}

Now, I have a list of these organisations and using LINQ, I would like to sort/order the output as follows:

1) Organisations: Ordered by Code and Name

2) Departments: Ordered by Code and Name

3) Employees: Ordered by Code and Name

Below is some test data that I have populated:

var britishTelecomLtd = new Organisation
            {
                Code = 8,
                Name = "British Telecom Ltd",
                Type = "Institutional",
                Departments =  new List<Department>
                    {
                        new Department
                            {
                                Code = 6,
                                Name = "Finance",
                                Employees = new List<Employee>
                                    {
                                        new Employee
                                            {
                                                Code = 5,
                                                Name = "Peter"
                                            },
                                            new Employee
                                            {
                                                Code = 2,
                                                Name = "James"
                                            },
                                            new Employee
                                            {
                                                Code = 6,
                                                Name = "Andrew"
                                            }
                                    }
                            },
                            new Department
                            {
                                Code = 5,
                                Name = "Accounts",
                                Employees = new List<Employee>
                                    {
                                        new Employee
                                            {
                                                Code = 15,
                                                Name = "Jane"
                                            },
                                            new Employee
                                            {
                                                Code = 22,
                                                Name = "John"
                                            },
                                            new Employee
                                            {
                                                Code = 16,
                                                Name = "Mark"
                                            }
                                    }
                            }

                    } 

            };

        var virginMediaLtd = new Organisation
        {
            Code = 5,
            Name = "Virgin Media Ltd",
            Type = "Institutional",
            Departments = new List<Department>
                    {
                        new Department
                            {
                                Code = 6,
                                Name = "Sales",
                                Employees = new List<Employee>
                                    {
                                       new Employee
                                            {
                                                Code = 5,
                                                Name = "Peter"
                                            },
                                            new Employee
                                            {
                                                Code = 2,
                                                Name = "James"
                                            },
                                            new Employee
                                            {
                                                Code = 6,
                                                Name = "Andrew"
                                            }
                                    }
                            },
                            new Department
                            {
                                Code = 5,
                                Name = "Support",
                                Employees = new List<Employee>
                                    {
                                        new Employee
                                            {
                                                Code = 15,
                                                Name = "Jane"
                                            },
                                            new Employee
                                            {
                                                Code = 22,
                                                Name = "John"
                                            },
                                            new Employee
                                            {
                                                Code = 16,
                                                Name = "Mark"
                                            }
                                    }
                            }

                    }

        };

        var pcWorldLtd = new Organisation
        {
            Code = 18,
            Name = "PC World Ltd",
            Type = "Retail",
            Departments = new List<Department>
                    {
                        new Department
                            {
                                Code = 6,
                                Name = "Marketing",
                                Employees = new List<Employee>
                                    {
                                          new Employee
                                            {
                                                Code = 15,
                                                Name = "Jane"
                                            },
                                            new Employee
                                            {
                                                Code = 22,
                                                Name = "John"
                                            },
                                            new Employee
                                            {
                                                Code = 16,
                                                Name = "Mark"
                                            }
                                    }
                            },
                            new Department
                            {
                                Code = 5,
                                Name = "Customer Services",
                                Employees = new List<Employee>
                                    {
                                         new Employee
                                            {
                                                Code = 5,
                                                Name = "Kelly"
                                            },
                                            new Employee
                                            {
                                                Code = 2,
                                                Name = "Jenny"
                                            },
                                            new Employee
                                            {
                                                Code = 6,
                                                Name = "Tricia"
                                            }
                                    }
                            }

                    }

        };

        var blueCatLtd = new Organisation
            {
                Code = 3,
                Name = "Blue Cat Music Ltd",
                Type = "Retail",
                Departments = new List<Department>
                    {
                        new Department
                            {
                                Code = 6,
                                Name = "Sales",
                                Employees = new List<Employee>
                                    {
                                         new Employee
                                            {
                                                Code = 5,
                                                Name = "Peter"
                                            },
                                            new Employee
                                            {
                                                Code = 2,
                                                Name = "James"
                                            },
                                            new Employee
                                            {
                                                Code = 6,
                                                Name = "Andrew"
                                            }
                                    }
                            },
                        new Department
                            {
                                Code = 5,
                                Name = "Warehouse",
                                Employees = new List<Employee>
                                    {
                                        new Employee
                                            {
                                                Code = 5,
                                                Name = "Andy"
                                            },
                                        new Employee
                                            {
                                                Code = 2,
                                                Name = "Robert"
                                            },
                                        new Employee
                                            {
                                                Code = 6,
                                                Name = "Dave"
                                            }
                                    }
                            }

                    }
            };

        var organisations = new List<Organisation>
            {
                britishTelecomLtd,
                virginMediaLtd,
                pcWorldLtd,
                blueCatLtd
            };

Here I am adding the data to a dictionary:

   var legalEntitiesCollectionByType = new Dictionary<string, ICollection<Organisation>>
            {
                {
                    "Institutional", organisations
                        .Where(x => x.Type == "Institutional")
                        .OrderBy(x => x.Code).ThenBy(x => x.Name)
                        .ToList()
                },
                {
                    "Retail", organisations
                        .Where(x => x.Type == "Retail")
                        .OrderBy(x => x.Code).ThenBy(x => x.Name)
                        .ToList()
                }
            };

doing it this way the sorting only happens at the Organisation level and not on the department or the employee level.

My question is, how can I achieve sorting on all 3 levels within the object hierarchy while populating the dictionary above?

Cheers

Answer 1

You can sort before :

    organisations.ToList().ForEach(o => o.Departments = o.Departments.OrderBy(d => d.Code).ToList());
    organisations.SelectMany(o => o.Departments).ToList().ForEach(d => d.Employees = d.Employees.OrderBy(e => e.Name).ToList());

And then use the list already sorted

        var legalEntitiesCollectionByType = new Dictionary<string, ICollection<Organisation>>
        {
            {
                "Institutional", organisations
                    .Where(x => x.Type == "Institutional")
                    .ToList()
            },
            {
                "Retail", organisations
                    .Where(x => x.Type == "Retail")
                    .ToList()
            }
        };

NB : the sort is not in place, you can achieve this using a comparer

        organisations.ToList().ForEach(o => o.Departments.Sort(CreateCustomComparison));
        organisations.SelectMany(o => o.Departments).ToList().ForEach(d => d.Employees.Sort(CreateCustomComparison));

Answer 2

If Employees ever need to be sorted by code and name then you can make that property a SortedList<>.

public class Department
{
    ...
    public SortedList<Tuple<int, string>, Employee> Employees { get; set; }
}

Prior to .NET 4 you could use KeyValuePair instead of Tuple.

When creating Employees object you'd need to provide IComparer object for sorted list's key.

Employees = new SortedList<Tuple<int, string>, Employee>(new EmployeeKeyComparer());

where EmployeeKeyComparer could be defined as

public class EmployeeKeyComparer : IComparer<Tuple<int, string>>
{
    public int Compare(Tuple<int, string> x, Tuple<int, string> y)
    {
        if (x.First == y.First)
            return StringComparer.Ordinal.Compare(x.Second, y.Second);
        else
            return x.First.CompareTo(y.First);
    }
}