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POLinq to SQL Repository question
 

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    <p>I am working on a similar project like NerdDinner (www.nerddinner.com). I have similar tables, but I have used a generic repository (copied from here <a href="http://www.codeproject.com/KB/architecture/linqrepository.aspx" rel="nofollow noreferrer">http://www.codeproject.com/KB/architecture/linqrepository.aspx</a>). It seems working without any problem. Here are the codes.</p> <hr> <h2>IRepository.cs</h2> <pre><code>using System; using System.Collections.Generic; using System.Text; using System.Data.Linq; using System.Linq; namespace Listing.Repository { public interface IRepository&lt;T&gt; where T : class { /// &lt;summary&gt; /// Return all instances of type T. /// &lt;/summary&gt; /// &lt;returns&gt;&lt;/returns&gt; IEnumerable&lt;T&gt; GetAllRows(); /// &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;&lt;/returns&gt; IEnumerable&lt;T&gt; GetAllRowsWhere(Func&lt;T, bool&gt; exp); /// &lt;summary&gt;Returns the single entity matching the expression. Throws an exception if there is not exactly one such entity.&lt;/summary&gt; /// &lt;param name="exp"&gt;&lt;/param&gt;&lt;returns&gt;&lt;/returns&gt; T Single(Func&lt;T, bool&gt; exp); /// &lt;summary&gt;Returns the first element satisfying the condition.&lt;/summary&gt; /// &lt;param name="exp"&gt;&lt;/param&gt;&lt;returns&gt;&lt;/returns&gt; T First(Func&lt;T, bool&gt; exp); /// &lt;summary&gt; /// Mark an entity to be deleted when the context is saved. /// &lt;/summary&gt; /// &lt;param name="entity"&gt;&lt;/param&gt; void Delete(T entity); /// &lt;summary&gt; /// Adds new entity.. /// &lt;/summary&gt; /// &lt;param name="entity"&gt;&lt;/param&gt; void Insert(T entity); void Update(T entity); /// &lt;summary&gt; /// Create a new instance of type T. /// &lt;/summary&gt; /// &lt;returns&gt;&lt;/returns&gt; T New(); /// &lt;summary&gt;Persist the data context.&lt;/summary&gt; void SaveAll(); } } </code></pre> <hr> <h2>Repository.cs</h2> <pre><code>using System; using System.Data; using System.Data.Linq; using System.Data.Linq.Mapping; using System.Collections.Generic; using System.Reflection; using System.Linq; using System.Linq.Expressions; namespace Listing.Repository { public class Repository&lt;T&gt; : IRepository&lt;T&gt; where T : class { protected Listing.Data.IDataContextFactory _dataContextFactory; /// &lt;summary&gt; /// Return all instances of type T. /// &lt;/summary&gt; /// &lt;returns&gt;&lt;/returns&gt; public IEnumerable&lt;T&gt; GetAllRows() { return GetTable; } /// &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;&lt;/returns&gt; public IEnumerable&lt;T&gt; GetAllRowsWhere(Func&lt;T, bool&gt; exp) { return GetTable.Where&lt;T&gt;(exp); } /// &lt;summary&gt;See _vertexRepository.&lt;/summary&gt; /// &lt;param name="exp"&gt;&lt;/param&gt;&lt;returns&gt;&lt;/returns&gt; public T Single(Func&lt;T, bool&gt; exp) { return GetTable.SingleOrDefault(exp); } /// &lt;summary&gt;See _vertexRepository.&lt;/summary&gt; /// &lt;param name="exp"&gt;&lt;/param&gt;&lt;returns&gt;&lt;/returns&gt; public T First(Func&lt;T, bool&gt; exp) { return GetTable.First(exp); } /// &lt;summary&gt;See _vertexRepository.&lt;/summary&gt; /// &lt;param name="entity"&gt;&lt;/param&gt; public virtual void Delete(T entity) { _dataContextFactory.Context.GetTable&lt;T&gt;().DeleteOnSubmit(entity); } /// &lt;summary&gt; /// Create a new instance of type T. /// &lt;/summary&gt; /// &lt;returns&gt;&lt;/returns&gt; public virtual T New() { T entity = Activator.CreateInstance&lt;T&gt;(); GetTable.InsertOnSubmit(entity); return entity; } /// &lt;summary&gt; /// Adds an insance T. /// &lt;/summary&gt; /// &lt;returns&gt;&lt;/returns&gt; public virtual void Insert(T entity) { GetTable.InsertOnSubmit(entity); } /// &lt;summary&gt; /// Update entity. /// &lt;/summary&gt; /// &lt;returns&gt;&lt;/returns&gt; public virtual void Update(T entity) { _dataContextFactory.Context.Refresh(System.Data.Linq.RefreshMode.KeepCurrentValues, entity); } /// &lt;summary&gt;See _vertexRepository.&lt;/summary&gt; public void SaveAll() { _dataContextFactory.SaveAll(); } public Repository(Listing.Data.IDataContextFactory dataContextFactory) { _dataContextFactory = dataContextFactory; } #region Properties private string PrimaryKeyName { get { return TableMetadata.RowType.IdentityMembers[0].Name; } } private System.Data.Linq.Table&lt;T&gt; GetTable { get { return _dataContextFactory.Context.GetTable&lt;T&gt;(); } } private System.Data.Linq.Mapping.MetaTable TableMetadata { get { return _dataContextFactory.Context.Mapping.GetTable(typeof(T)); } } private System.Data.Linq.Mapping.MetaType ClassMetadata { get { return _dataContextFactory.Context.Mapping.GetMetaType(typeof(T)); } } #endregion } } </code></pre> <hr> <h2>IDataContext.cs</h2> <pre><code>using System; using System.Linq; namespace Listing.Data { public interface IDataContextFactory { System.Data.Linq.DataContext Context { get; } void SaveAll(); } public class DataContext : IDataContextFactory { #region IDataContextFactory Members private System.Data.Linq.DataContext dt; public System.Data.Linq.DataContext Context { get { if (dt == null) dt = new Listing.Data.ListingDataContext(); return dt; } } public void SaveAll() { dt.SubmitChanges(); } #endregion } } </code></pre> <hr> <p>Now I am in a stage where I have dropped a two functions DistanceBetween and NearestDinners(mine one's name is different), to my dbml file. I want to use these functions to do some calculation. </p> <p>Here are the codes used in nerddinner project </p> <pre><code>public IQueryable&lt;Dinner&gt; FindByLocation(float latitude, float longitude) { var dinners = from dinner in FindUpcomingDinners() join i in db.NearestDinners(latitude, longitude) on dinner.DinnerID equals i.DinnerID select dinner; return dinners; } </code></pre> <p>How would I achieve similar with my generic Repository. Help will be appreciated. </p> <p>Regards Paraminder</p>
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