user defined collection

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I am creating a user defined collection.

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace CompanyDocs
{
    public class Documents
    {
        public string Name;
        public string Surname;
        public string Title;
        //Constructors
        public Documents()
        {}
        public Documents(string iName, string iSurname, string iTitle)
        {
            Name = iName;
            Surname = iSurname;
            Title = iTitle;
        }
        public virtual string GetData()
        {
            return Name + " - " + Surname + " : " + Title;
        }
    }
}

This is my Collection:

C#

namespace CompanyDocs
{
    public class StoreObjects:List<Documents>
    {
        
        public StoreObjects() { } //Constructor

        public void GetDataOfAll()
        {
            foreach (Documents d in this)
                Console.WriteLine(d.GetData());
        }
    }
}

I have 2 forms: 1 is where I am inputting data, where I have 3 text boxes (i.e. Name Surname Title), and have to buttons one is to show all the data in a RichTextBox within the same form. The other button calls another form where I have a button and textbox to be able to search for a Document by Title, and display the result in another RichTextBox within Form2.

I am getting stuck of how to display this data

What I need is that :
1. the method GetDataOfAll() returns a string instead of void
2. how can i implement the search facility.

Thanks

Posted 22-Jan-11 20:58pm

datt265

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2 solutions

Solution 1

This is what I was asked to do:

A) The IT section of a company is using a collection to store objects containing information about
company's documents. The types of Documents to be stored on the collection are:
- Each document has the Surname and Name of the author and Title

The following are queries / operations to be carried out:
- listing of all company’s documents while displaying all details of a particular document
- searching the collection for a particular document by surname of author

- each class must have or inherit the method GetData() returning string composed of ALL
class’s data

B) Implement the classes in a C# Windows application program
- a constructor of an upmost ancestor of the class hierarchy which, apart from the
construction, initializes ALL its data fields
the method GetData() for class Documents

C) a collection class dedicated to store all objects of company documents
as per the class hierarchy, inheriting from any .NET suitable collection class (e.g. the ArrayList
class, or generic List). The collection is to implement a single method GetDataOfAll() returning
a string which concatenates data of all objects with suitable separators. (The method will later
be used to display data in a suitable output placeholder)

D) Extend the functionality of the collection by the following method:
SearchByTitle(string aTitle)
which searches the collection for a matching title, returning the reference to the document
object or null, if not found.

Posted 22-Jan-11 21:18pm

datt265

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OriginalGriff · Accepted Answer · 2011-01-22T21:30:00

Firstly, change the name of your class from "Documents" to "Document": the plural implies it contains more than one document, which it doesn't. What could you call an array of "Documents"? If you do not use plurals for singular objects you can write code which is immediately obvious:

C#

Document[] documents = myLibrary.GetAll("Hamsters");
foreach (Document document in documents)
   {
   ...
   }

Additionally, consider changing the name of your StoreObjects class: Does it store "Object" items? or "Document" items?

Secondly, to return a string instead of a void:

C#

public string GetDataOfAll()
   {
   StringBuilder sb = new Stringbuilder();
   foreach (Documents d in this)
      {
      sb.Append(d.GetData() + "\n");
      Console.WriteLine(d.GetData());
      }
   return sb.ToString();
   }

You don't have to use a StringBuilder, you could just concatenate the strings with

C#

myReturnString += d.GetData();

But StringBuilder is a lot more efficient.

Thirdly, to search, provide two routines:
In StoreObjects:

C#

public Document Find(string searchText)
   {
   foreach (Document document in this)
      {
      if (document.Find(searchText))
         {
         return document;
         }
      }
   return null;
   }

In Document:

C#

public bool Find(string searchText)
   {
   bool found = false;
   // Do your document search here, and set "found" to "true" if you find the text
   return found;
   }

I leave the document search to you, as I have no idea of your document content!

"Should I call which method from my Form? the method in Document or the one in myLibrary?"

In your form, you only need to call the method in your library, you don't need the foreach loop as it is inside the library method:

C#

Document d = myLib.Find(txtTitle.Text);
if (d != null)
   {
   // Found the document!
   richTextBox1.AppendText(d.GetData() + "\n");
   ...
   }

This way it is kept cleaner: your form doesn't need to know what your library does to store the documents: you just say "Give me this document" and it does all the work. That way, the Library can change in future, without the form having to change to keep up.

For that reason, I wouldn't derive the Library from the List directly, but would embed the list in the library as a private class variable. It means you have to add the "Add" and "Remove" methods yourself, but it abstracts your data store so it is easier to change in future if you need to. The Add and Remove just call the appropriate methods of the private list.