Refactoring the set of Predicate with an Interpreter

To achieve this I first added two more properties to my Entity, Article. I
did not added new constructors because those two properties are not
mandatory:

1 private DateTime datePublished;
2
3 public DateTime DatePublished
4 {
5 get { return datePublished; }
6 set { datePublished = value; }
7 }
8
9 private DateTime dateModified;
10
11 public DateTime DateModified
12 {
13 get { return dateModified; }
14 set { dateModified = value; }
15 }

Then I modified my Data Access Layer to have it a bit more generic, starting with the interface :

1 interface IDataAccess
2 {
3 List GetAll();
4
5 List FindAll(Predicate match);
6 }
7

I removed the method “T Get(Guid uuid)” and “T Get(string uuid)” because that can be easily expressed with a Predicate.

I made a Generic implementation of my Data Access through a DataAccessor class:

1 namespace TechHeadBrothers.Portal.DAL
2 {
3 public class DataAccessor : IDataAccess where T : new()
4 {
5 List list = null;
6
7 public DataAccessor(string sp)
8 {
9 readFromDatabase(sp);
10 }
11
12 #region Protected Methods
13
14 protected void readFromDatabase(string sp)
15 {
16 // Create Instance of Connection and Command Object
17 SqlConnection myConnection =
18 new SqlConnection(ConfigurationManager.ConnectionStrings[“TechHeadBrothers”].ConnectionString);
19
20 SqlDataAdapter myCommand = new SqlDataAdapter(sp, myConnection);
21
22 // Mark the Command as a SPROC
23 myCommand.SelectCommand.CommandType = CommandType.StoredProcedure;
24
25 // Create and Fill the DataSet
26 DataSet ds = new DataSet();
27 myCommand.Fill(ds);
28
29 myConnection.Close();
30
31 this.list = DataAdapterFactory.createAdapter().Adapt(ds.Tables[0]);
32 }
33
34 #endregion
35
36 #region IDataAccess Members
37
38 public List GetAll()
39 {
40 return list;
41 }
42
43 public List FindAll(Predicate match)
44 {
45 return list.FindAll(match);
46 }
47
48 #endregion
49 }
50 }

I had to implement an Adapter to convert the data from the Database representation to the Entity :

1 abstract class DataAdapter
2 {
3 public List Adapt(DataTable table)
4 {
5 List list = new List(table.Rows.Count);
6
7 foreach (DataRow row in table.Rows)
8 {
9 list.Add(this.Adapt(row));
10 }
11
12 return list;
13 }
14
15 public abstract T Adapt(DataRow row);
16 }

And a Factory :

1 class DataAdapterFactory
2 {
3 public static DataAdapter createAdapter() where T : new()
4 {
5 string name = new T().GetType().Name.ToLower();
6
7 if ( name == “article”)
8 return new ArticleAdapter() as DataAdapter;
9 else if ( name == “author”)
10 return new AuthorAdapter() as DataAdapter;
11
12 return null;
13 }
14 }

Here is the concrete implementation for the Article Entity Adapter:

1 class ArticleAdapter : DataAdapter