From b63d205057af361b6bb0e5bacc031a735b273e8c Mon Sep 17 00:00:00 2001
From: Edgar Mesquita <edgarmesquita@Mindera-MBP.lan>
Date: Mon, 4 Sep 2023 22:17:50 +0100
Subject: [PATCH] feat: Implementing generic Get Entity By Id Specification

---
 .../Extensions/DbContextExtensions.cs         | 42 +++++++++++++++++++
 src/Repository/Set.cs                         | 30 +------------
 src/Repository/UnitOfWork.cs                  |  2 +
 .../GetEntityByIdSpecification.cs             | 25 +++++++++++
 src/eQuantic.Core.Data.EntityFramework.csproj |  6 +--
 5 files changed, 73 insertions(+), 32 deletions(-)
 create mode 100644 src/Repository/Extensions/DbContextExtensions.cs
 create mode 100644 src/Specifications/GetEntityByIdSpecification.cs

diff --git a/src/Repository/Extensions/DbContextExtensions.cs b/src/Repository/Extensions/DbContextExtensions.cs
new file mode 100644
index 0000000..95d95f8
--- /dev/null
+++ b/src/Repository/Extensions/DbContextExtensions.cs
@@ -0,0 +1,42 @@
+using System;
+using System.Linq;
+using System.Linq.Expressions;
+using Microsoft.EntityFrameworkCore;
+
+namespace eQuantic.Core.Data.EntityFramework.Repository.Extensions;
+
+public static class DbContextExtensions
+{
+    public static Expression<Func<TEntity, bool>> GetFindByKeyExpression<TEntity, TKey>(this DbContext dbContext, TKey id)
+    {
+        var primaryKey = dbContext.Model.FindEntityType(typeof(TEntity))!.FindPrimaryKey()!.Properties
+            .FirstOrDefault();
+        if (primaryKey == null)
+        {
+            return null;
+        }
+
+        var keyProperty = typeof(TEntity).GetProperty(primaryKey.Name);
+
+        if (keyProperty == null)
+        {
+            return null;
+        }
+
+        // Create entity => portion of lambda expression
+        var parameter = Expression.Parameter(typeof(TEntity), "entity");
+
+        // create entity.Id portion of lambda expression
+        var property = Expression.Property(parameter, keyProperty.Name);
+
+        // create 'id' portion of lambda expression
+        var equalsTo = Expression.Constant(id);
+
+        // create entity.Id == 'id' portion of lambda expression
+        var equality = Expression.Equal(property, equalsTo);
+
+        // finally create entire expression - entity => entity.Id == 'id'
+        var retVal = Expression.Lambda<Func<TEntity, bool>>(equality, new[] { parameter });
+        return retVal;
+    }
+}
\ No newline at end of file
diff --git a/src/Repository/Set.cs b/src/Repository/Set.cs
index a399640..18a744a 100644
--- a/src/Repository/Set.cs
+++ b/src/Repository/Set.cs
@@ -373,35 +373,7 @@ private async Task LoadCascadeAsync(string[] props, object obj, int index = 0)
 
     internal Expression<Func<TEntity, bool>> GetExpression<TKey>(TKey id)
     {
-        var primaryKey = _dbContext.Model.FindEntityType(typeof(TEntity))!.FindPrimaryKey()!.Properties
-            .FirstOrDefault();
-        if (primaryKey == null)
-        {
-            return null;
-        }
-
-        var keyProperty = typeof(TEntity).GetProperty(primaryKey.Name);
-
-        if (keyProperty == null)
-        {
-            return null;
-        }
-
-        // Create entity => portion of lambda expression
-        var parameter = Expression.Parameter(typeof(TEntity), "entity");
-
-        // create entity.Id portion of lambda expression
-        var property = Expression.Property(parameter, keyProperty.Name);
-
-        // create 'id' portion of lambda expression
-        var equalsTo = Expression.Constant(id);
-
-        // create entity.Id == 'id' portion of lambda expression
-        var equality = Expression.Equal(property, equalsTo);
-
-        // finally create entire expression - entity => entity.Id == 'id'
-        var retVal = Expression.Lambda<Func<TEntity, bool>>(equality, new[] { parameter });
-        return retVal;
+        return _dbContext.GetFindByKeyExpression<TEntity, TKey>(id);
     }
 
     private static TConfig GetConfig<TConfig>(Action<TConfig> configuration)
diff --git a/src/Repository/UnitOfWork.cs b/src/Repository/UnitOfWork.cs
index 242336e..25a0e5f 100644
--- a/src/Repository/UnitOfWork.cs
+++ b/src/Repository/UnitOfWork.cs
@@ -20,6 +20,8 @@ public abstract class UnitOfWork : SqlExecutor
     protected UnitOfWork(DbContext context) : base(context)
     {
     }
+    
+    internal DbContext GetDbContext() => Context;
 }
 
 public abstract class UnitOfWork<TUnitOfWork, TDbContext> : UnitOfWork<TDbContext>, ISqlUnitOfWork<TUnitOfWork>
diff --git a/src/Specifications/GetEntityByIdSpecification.cs b/src/Specifications/GetEntityByIdSpecification.cs
new file mode 100644
index 0000000..cf5cd53
--- /dev/null
+++ b/src/Specifications/GetEntityByIdSpecification.cs
@@ -0,0 +1,25 @@
+using System;
+using System.Linq.Expressions;
+using eQuantic.Core.Data.EntityFramework.Repository;
+using eQuantic.Core.Data.EntityFramework.Repository.Extensions;
+using eQuantic.Core.Data.Repository;
+using eQuantic.Linq.Specification;
+
+namespace eQuantic.Core.Data.EntityFramework.Specifications;
+
+public class GetEntityByIdSpecification<TEntity, TKey> : Specification<TEntity>
+    where TEntity : class, IEntity<TKey>, new()
+{
+    private readonly TKey _id;
+    private readonly UnitOfWork _unitOfWork;
+
+    public GetEntityByIdSpecification(TKey id, UnitOfWork unitOfWork)
+    {
+        _id = id;
+        _unitOfWork = unitOfWork;
+    }
+    public override Expression<Func<TEntity, bool>> SatisfiedBy()
+    {
+        return _unitOfWork.GetDbContext().GetFindByKeyExpression<TEntity, TKey>(_id);
+    }
+}
\ No newline at end of file
diff --git a/src/eQuantic.Core.Data.EntityFramework.csproj b/src/eQuantic.Core.Data.EntityFramework.csproj
index c1a4b5f..93fc1aa 100644
--- a/src/eQuantic.Core.Data.EntityFramework.csproj
+++ b/src/eQuantic.Core.Data.EntityFramework.csproj
@@ -4,7 +4,7 @@
 	<PropertyGroup>
 		<Description>Core Data library for Entity Framework</Description>
 		<AssemblyTitle>eQuantic.Core.Data.EntityFramework</AssemblyTitle>
-		<Version>4.0.3.0</Version>
+		<Version>4.0.4.0</Version>
 		<Authors>eQuantic Systems</Authors>
 		<TargetFrameworks>netstandard2.1;net6.0;net7.0</TargetFrameworks>
 		<AssemblyName>eQuantic.Core.Data.EntityFramework</AssemblyName>
@@ -23,8 +23,8 @@
 		<PackageLicenseFile>LICENSE</PackageLicenseFile>
 		<PackageReadmeFile>README.md</PackageReadmeFile>
 		<Copyright>Copyright ©  2016</Copyright>
-		<AssemblyVersion>4.0.3.0</AssemblyVersion>
-		<FileVersion>4.0.3.0</FileVersion>
+		<AssemblyVersion>4.0.4.0</AssemblyVersion>
+		<FileVersion>4.0.4.0</FileVersion>
 		<PackageIcon>Icon.png</PackageIcon>
 		<LangVersion>latest</LangVersion>
 	</PropertyGroup>