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PORepository Pattern Implementation Experience
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  1. PORepository Pattern Implementation Experience
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    copied!<p>I am getting ready to start a new asp.net web project, and I am going to LINQ-to-SQL. I have done a little bit of work getting my data layer setup using some info I found by <a href="http://mikehadlow.blogspot.com/" rel="nofollow noreferrer" title="Mike Hadlow">Mike Hadlow</a> that uses an Interface and generics to create a Repository for each table in the database. I thought this was an interesting approach at first. However, now I think it might make more sense to create a base Repository class and inherit from it to create a TableNameRepository class for the tables I need to access. </p> <p>Which approach will be allow me to add functionality specific to a Table in a clean testable way? Here is my Repository implementation for reference.</p> <pre><code>public class Repository&lt;T&gt; : IRepository&lt;T&gt; where T : class, new() { protected IDataConnection _dcnf; public Repository() { _dcnf = new DataConnectionFactory() as IDataConnection; } // Constructor injection for dependency on DataContext // to actually connect to a database public Repository(IDataConnection dc) { _dcnf = dc; } /// &lt;summary&gt; /// Return all instances of type T. /// &lt;/summary&gt; /// &lt;returns&gt;IEnumerable&lt;T&gt;&lt;/returns&gt; public virtual IEnumerable&lt;T&gt; GetAll() { return GetTable; } public virtual T GetById(int id) { var itemParam = Expression.Parameter(typeof(T), "item"); var whereExp = Expression.Lambda&lt;Func&lt;T, bool&gt;&gt; ( Expression.Equal( Expression.Property(itemParam, PrimaryKeyName), Expression.Constant(id) ), new ParameterExpression[] { itemParam } ); return _dcnf.Context.GetTable&lt;T&gt;().Where(whereExp).Single(); } /// &lt;summary&gt; /// Return all instances of type T that match the expression exp. /// &lt;/summary&gt; /// &lt;param name="exp"&gt;&lt;/param&gt; /// &lt;returns&gt;IEnumerable&lt;T&gt;&lt;/returns&gt; public virtual IEnumerable&lt;T&gt; FindByExp(Func&lt;T, bool&gt; exp) { return GetTable.Where&lt;T&gt;(exp); } /// &lt;summary&gt;See IRepository.&lt;/summary&gt; /// &lt;param name="exp"&gt;&lt;/param&gt;&lt;returns&gt;&lt;/returns&gt; public virtual T Single(Func&lt;T, bool&gt; exp) { return GetTable.Single(exp); } /// &lt;summary&gt;See IRepository.&lt;/summary&gt; /// &lt;param name="entity"&gt;&lt;/param&gt; public virtual void MarkForDeletion(T entity) { _dcnf.Context.GetTable&lt;T&gt;().DeleteOnSubmit(entity); } /// &lt;summary&gt; /// Create a new instance of type T. /// &lt;/summary&gt; /// &lt;returns&gt;T&lt;/returns&gt; public virtual T Create() { //T entity = Activator.CreateInstance&lt;T&gt;(); T entity = new T(); GetTable.InsertOnSubmit(entity); return entity; } /// &lt;summary&gt;See IRepository.&lt;/summary&gt; public virtual void SaveAll() { _dcnf.SaveAll(); } #region Properties private string PrimaryKeyName { get { return TableMetadata.RowType.IdentityMembers[0].Name; } } private System.Data.Linq.Table&lt;T&gt; GetTable { get { return _dcnf.Context.GetTable&lt;T&gt;(); } } private System.Data.Linq.Mapping.MetaTable TableMetadata { get { return _dcnf.Context.Mapping.GetTable(typeof(T)); } } private System.Data.Linq.Mapping.MetaType ClassMetadata { get { return _dcnf.Context.Mapping.GetMetaType(typeof(T)); } } #endregion } </code></pre>
 

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