Collections within a collection?

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Hi All,
Hoping someone can point me in the right direction (or at least the key words so I can google it without getting bamboozled with it!).

The (hypothetical) scenario is this:
I have a collection of person objects but within the person object is a collection of fruit objects.

The fruit object contains information on name, country of origin and where bought.

Question 1 - should I have the collection of fruits within the person object, or, thinking about it from a database point of view, have a separate collection of fruits linked up to the person (note, I can't use a database to store all the information, hence my conundrum)?

Question 2 - One of the main requirements will be to select all people who buy the same collection of fruits (i.e. the number of fruits in the collection is the same and the type/country of origin is this same - where bought is just an additional piece of info but not used for matching). Any pointers on the best way around to achieve this?

If someone could please point me in the right direction, I'd appreciate it. No hurry as I'm just wondering if this hypothetical scenario is achievable in an easy way!

Thanks in Advance.

Posted 13-Jun-11 0:08am

Nebula2028

Updated 13-Jun-11 0:24am

Ramalinga Koushik

v2

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Nebula2028 14-Jun-11 5:40am

Thanks for the idea's and help all. I can see ideas from both solutions which I can use but Bob's solution does feel closer to what I'm after. Next steps for me will be digging deeper into LINQ queries I think! Thanks again.

2 solutions

Solution 2

class Person
{
    public string Name { get; set; }
    public Fruits FruitsItem { get; set; }
    //now you can get the details like this....
    List<Person> _allPerson = new List<Person>();
    private List<Person> CreateCollection()
    {
        _allPerson.Add(new Person { Name = "person1", FruitsItem = new Fruits { Name = "Mango", Country="India", Origin="origin", PurchaseLocation="Banglure" } });
        _allPerson.Add(new Person { Name = "person2", FruitsItem = new Fruits { Name = "Orange", Country = "India", Origin = "origin", PurchaseLocation = "Banglure" } });
        _allPerson.Add(new Person { Name = "person3", FruitsItem = new Fruits { Name = "Mango", Country = "India", Origin = "origin", PurchaseLocation = "Banglure" } });
        _allPerson.Add(new Person { Name = "person4", FruitsItem = new Fruits { Name = "Apple", Country = "India", Origin = "origin", PurchaseLocation = "Banglure" } });
        _allPerson.Add(new Person { Name = "person5", FruitsItem = new Fruits { Name = "Mango", Country = "India", Origin = "origin", PurchaseLocation = "Banglure" } });
        return _allPerson;
    }
    private List<Person> GetCollection()
    {
        var temp = CreateCollection().ToArray();
        var item = from t in temp
                    where t.FruitsItem.Name = "Apple" //your choicc
                    select t;
        return item;
    }
}
class Fruits
{
    public string Name { get; set; }
    public string Origin { get; set; }
    public string Country { get; set; }
    public string PurchaseLocation { get; set; }
}

Posted 13-Jun-11 1:14am

parmar_punit

Comments

BobJanova 13-Jun-11 9:22am

This solution will give people 1 and 5 a different instance of 'Mango/India'. In database terms, it is not normalised.

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BobJanova · Accepted Answer · 2011-06-13T01:06:00

The collection should be within the parent object when that tree relationship makes sense – i.e., if a fruit is associated with exactly one person. For any individual item of fruit that may be the case, but for fruit types, it is not. So I would go for something like

class Person {
 List<FruitItem> Fruits;

 string Name, Address; // etc
}

class FruitItem {
 FruitType Type;
 int Mass;
 Location WhereBought;
 // Anything else that applies to THIS PARTICULAR piece of fruit
 // e.g. condition, ID number
}

class FruitType {
 string Name;
 string CountryOfOrigin;
 // Anything else that applies to THIS TYPE of fruit
 // e.g. supplier, class, maybe batch number
}

class DataModel {
 List<Person> People;
 List<FruitType> FruitTypes;
}

Question 2 is then just comparing collections. Add equality functions to FruitType to test what you want as 'equal':

class FruitItem {
 ...

 public override Equals(object other){
  FruitItem otherFruit = other as FruitItem;
  return otherFruit != null && otherFruit.FruitType == FruitType;
 }

 public override int GetHashCode() { return FruitType.GetHashCode(); }
}

... and then write some code to compare the lists in the two people you want to check. (Is there a clever way, or is this 'sort and then compare items'?) Or if you want to do a grouping, make sure that the hash codes for a collection are calculated based on only their contents, and then use Linq to group on Fruits.GetHashCode().