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lightweight readonly datasource for combo/grid

Posted on 2006-06-09
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Last Modified: 2010-04-16
Hi!

We're looking for the most lightweight solution (memory/speed) for the implementation of a readonly datasource that can be used as a source for single/multi column comboboxes and grids.

Currently we are looking at  deriving from collectionbase thats stores objects made up of a few strings that are accessible using properties, which hence makes them useable as valuemember/displaymember.

2 questions about this:
-is this the best solution we can go at considering our needs? Can we go further so that boxing/unboxing is avoided(other collections?)
-Right now we work with objects that have a property for each member, but if we get the data from a database we do not know the number of columns so: how do we make an object that will dynamically have a property for each column that is stored?

500 points are awarded to whoever provides a helpful answer and some example code.

greetings

Secuteamers
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Question by:secuteamers
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existenz2 earned 500 total points
ID: 16869199
The most lightweight option i think is using an array of structs, possible enhanced with some extra functionality (if needed).

-Right now we work with objects that have a property for each member, but if we get the data from a database we do not know the number of columns so: how do we make an object that will dynamically have a property for each column that is stored?

That is a very tricky one. You have a few options:
Option 1:
Use Reflection to create classes with the approriate methods. Pro: 1 property foreach column, Cons: Very slow and not very lightweight.

Option 2:
Create a class which implements a enumerator and which loops through all columns, sorta like:
public class ExampleData : IEnumerator
      {
            DataRow dataRow = null;
            DataColumn dc = new DataColumn();
            int index = 0;

            public ExampleData(DataRow row)
            {
                  dataRow = row;
            }

            public bool MoveNext()
            {
                  bool next = false;
                  index++;
                  if(index <= (dataRow.ItemArray.Length-1))
                        next = true;
                  return next;
            }

            public void Reset()
            {
                  index = 0;
            }

            public object Current
            {
                  get { return dataRow[index]; }
            }

            public object[] All
            {
                  get
                  {
                        object[] data = new object[dataRow.ItemArray.Length];
                        for(int i = 0; i < dataRow.ItemArray.Length; i++)
                        {
                              data[i] = dataRow[i];
                        }
                        return data;
                  }
            }
      }
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Author Comment

by:secuteamers
ID: 16869423
been doing some further research, looking into Ilistsource interface, which should do the trick as far as i have read? Continuing...
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LVL 14

Expert Comment

by:existenz2
ID: 16869478
Yes, implementing IListSource would be a tider solution then my second option, with the same result.
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