C＃以单一方法将通用接口派生的对象添加到集合中

Question

I have two types of objects, sharing a common interface. I need to create these objects from data stored in two different tables in a database and formatted into two separate .NET DataTables.

These objects are fundamentally the same, with some distinct properties for each.

 public interface IRecord
{
     int Record_ID { get; set; }
     //Other Properties
}

Class TypeA: IRecord
Class TypeB: IRecord

DataTable TypeARecords
DataTable TypeBRecords

The Problem

I need these objects in a single collection of type IRecord, which is of class scope.

I currently have two methods that handle the creation of each type of object and add it to the collection. These methods are identical with the exception of the objects being worked with. I would like to combine these into a single method that accomplishes the following:

1. Determine what type of object should be created.
2. Determine if that object already exists in the collection using the type of the object and the 'RECORD_ID'
3. Add the objects to a single collection of type IRecord

Here is an example of the method that acts on objects of TypeA

List<IRecord> records; //This may or may not have anything in it, initially.

private void CreateTypeAObjects()
{

     DataTable TypeARecords = GetDataMethod();


        foreach (DataRow row in TypeARecords.Rows)
        {
            int recordID = int.Parse(row["Record_ID"].ToString());


            if (records != null && records.Count > 0)
            {
                //If the record is of TypeA and doesn't have an existing object in the collection, create it.
                if ((!records.Where(t => t is TypeA).Any(s => s.Record_ID == recordID)))
                {
                    records.Add(new TypeA
                    {
                        Record_ID = int.Parse(row["Record_ID"].ToString()),
                        //Initialize other properties
                    });

                }
            }
            else
            {
           //If the list is not instantiated, create it now and add record.
                records = new List<IRecord>();
                records.Add(new TypeA
                {
                    Record_ID = int.Parse(row["Record_ID"].ToString()),
                    //Initialize Other Properties

                });
            }

        }
}

Answer 1

You could pass in the DataTable and the Type into the GetDataMethod() function.

List<IRecord> records = new List<IRecord>();

private void CreateAllObjects(System.Type _type, DataTable table)
{

    foreach (DataRow row in table.Rows)
    {
        int recordID = int.Parse(row["Record_ID"].ToString());


        //If the record is of the passed in type and doesn't have an existing object in the collection, create it.
        if ((!records.Where(t => t is _type).Any(s => s.Record_ID == recordID)))
            {

                IRecord record = (IRecord)Activator.CreateInstance(_type);
                //initialize record
                records.Add(record);

            }  

    }
}

A DataTable is a DataTable and you can use the Activator to instantiate each type.

You call that function twice to get your data loaded. I took the liberty of simplifying your logic based on the assumption that I could initialize the records list when it is declared.

CreateAllObjects(TypeA, TypeARecords);
CreateAllObjects(TypeB, TypeBRecords);