Modifying Entity Framework for use by a Repository and Unit of Work Pattern

Enabling Auto Code Generation of Entity Framework Database First for use with a Generic Repository

Introduction

In a related post, we discussed accessing data through a generic repository with Entity Framework. Here, we will elaborate further on this and show how to modify the the Model.Context.tt file to auto-generate the refactored Model.Context.cs code for use with a generic repository.

Background

We want to modify the Model.Context.tt file as any changes we make to Model.Context.cs will be overwritten by Entity Framework Database First.  If you wish, you can update the *.cs file directly, but be warned that those changes may be overwritten.

If you are not comfortable with overwriting the *.tt template, one suggestion I can make is to keep a separate copy of your code as a comment section in your project’s App.config file.

Updated Template (*.tt) Code

You can simply overwrite your Model.Context.tt code with the following and your Entity Framework data access will be compatible with a repository and unit of work pattern:


 

<#@ template language="C#" debug="false" hostspecific="true"#>
<#@ include file="EF.Utility.CS.ttinclude"#><#@
 output extension=".cs"#><#

const string inputFile = @"AtmsModel.edmx";
var textTransform = DynamicTextTransformation.Create(this);
var code = new CodeGenerationTools(this);
var ef = new MetadataTools(this);
var typeMapper = new TypeMapper(code, ef, textTransform.Errors);
var loader = new EdmMetadataLoader(textTransform.Host, textTransform.Errors);
var itemCollection = loader.CreateEdmItemCollection(inputFile);
var modelNamespace = loader.GetModelNamespace(inputFile);
var codeStringGenerator = new CodeStringGenerator(code, typeMapper, ef);

var container = itemCollection.OfType<EntityContainer>().FirstOrDefault();
if (container == null)
{
 return string.Empty;
}
#>
//------------------------------------------------------------------------------
// <auto-generated>
// <#=GetResourceString("Template_GeneratedCodeCommentLine1")#>
//
// <#=GetResourceString("Template_GeneratedCodeCommentLine2")#>
// <#=GetResourceString("Template_GeneratedCodeCommentLine3")#>
// </auto-generated>
//------------------------------------------------------------------------------

<#

var codeNamespace = code.VsNamespaceSuggestion();
if (!String.IsNullOrEmpty(codeNamespace))
{
#>
namespace <#=code.EscapeNamespace(codeNamespace)#>
{
<#
 PushIndent(" ");
}

#>
using System;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
<#
if (container.FunctionImports.Any())
{
#>
using System.Data.Objects;
using System.Data.Objects.DataClasses;
using System.Linq;
<#
}
#>

<#=Accessibility.ForType(container)#> partial class <#=code.Escape(container)#> : DbContext, IDbContext
{

 static <#=code.Escape(container)#>()
 {
 // if required, at this point we can check for a db's existance,
 // create a new database (code first), or seed the db with values
 Database.SetInitializer<<#=code.Escape(container)#>>(null);
 }
 public <#=code.Escape(container)#>()
 : base("name=<#=container.Name#>")
 {

 // To disable lazy loading, add the following to your Entity Container definition:
 // <EntityContainer Name="MyEntitiesContext" annotation:LazyLoadingEnabled="false">
 // This will automaticall add the following line when generating
 // this.Configuration.LazyLoadingEnabled = false;

<#
if (!loader.IsLazyLoadingEnabled(container))
{
#>
 this.Configuration.LazyLoadingEnabled = false;
<#
}
#>
 // Remove the following line if lazy loading has been disabled through the EntityContainer definition:
 Configuration.LazyLoadingEnabled = false;

}
 // Refactored for use by a generic repository
 public new IDbSet<T> Set<T>() where T : class
 {
 return base.Set<T>();
 }

public override int SaveChanges()
 {
 // this.ApplyStateChanges();
 return base.SaveChanges();
 }

protected override void OnModelCreating(DbModelBuilder modelBuilder)
 {
 throw new UnintentionalCodeFirstException();
 }

<#
 foreach (var entitySet in container.BaseEntitySets.OfType<EntitySet>())
 {
#>
 <#=codeStringGenerator.DbSet(entitySet)#>
<#
 }

foreach (var edmFunction in container.FunctionImports)
 {
 WriteFunctionImport(typeMapper, codeStringGenerator, edmFunction, modelNamespace, includeMergeOption: false);
 }
#>
}
<#

if (!String.IsNullOrEmpty(codeNamespace))
{
 PopIndent();
#>
}
<#
}
#>
<#+

private void WriteFunctionImport(TypeMapper typeMapper, CodeStringGenerator codeStringGenerator, EdmFunction edmFunction, string modelNamespace, bool includeMergeOption)
{
 if (typeMapper.IsComposable(edmFunction))
 {
#>

[EdmFunction("<#=edmFunction.NamespaceName#>", "<#=edmFunction.Name#>")]
 <#=codeStringGenerator.ComposableFunctionMethod(edmFunction, modelNamespace)#>
 {
<#+
 codeStringGenerator.WriteFunctionParameters(edmFunction, WriteFunctionParameter);
#>
 <#=codeStringGenerator.ComposableCreateQuery(edmFunction, modelNamespace)#>
 }
<#+
 }
 else
 {
#>

<#=codeStringGenerator.FunctionMethod(edmFunction, modelNamespace, includeMergeOption)#>
 {
<#+
 codeStringGenerator.WriteFunctionParameters(edmFunction, WriteFunctionParameter);
#>
 <#=codeStringGenerator.ExecuteFunction(edmFunction, modelNamespace, includeMergeOption)#>
 }
<#+
 if (typeMapper.GenerateMergeOptionFunction(edmFunction, includeMergeOption))
 {
 WriteFunctionImport(typeMapper, codeStringGenerator, edmFunction, modelNamespace, includeMergeOption: true);
 }
 }
}

public void WriteFunctionParameter(string name, string isNotNull, string notNullInit, string nullInit)
{
#>
 var <#=name#> = <#=isNotNull#> ?
 <#=notNullInit#> :
 <#=nullInit#>;

<#+
}

public const string TemplateId = "CSharp_DbContext_Context_EF5";

public class CodeStringGenerator
{
 private readonly CodeGenerationTools _code;
 private readonly TypeMapper _typeMapper;
 private readonly MetadataTools _ef;

public CodeStringGenerator(CodeGenerationTools code, TypeMapper typeMapper, MetadataTools ef)
 {
 ArgumentNotNull(code, "code");
 ArgumentNotNull(typeMapper, "typeMapper");
 ArgumentNotNull(ef, "ef");

_code = code;
 _typeMapper = typeMapper;
 _ef = ef;
 }

public string Property(EdmProperty edmProperty)
 {
 return string.Format(
 CultureInfo.InvariantCulture,
 "{0} {1} {2} {{ {3}get; {4}set; }}",
 Accessibility.ForProperty(edmProperty),
 _typeMapper.GetTypeName(edmProperty.TypeUsage),
 _code.Escape(edmProperty),
 _code.SpaceAfter(Accessibility.ForGetter(edmProperty)),
 _code.SpaceAfter(Accessibility.ForSetter(edmProperty)));
 }

public string NavigationProperty(NavigationProperty navigationProperty)
 {
 var endType = _typeMapper.GetTypeName(navigationProperty.ToEndMember.GetEntityType());
 return string.Format(
 CultureInfo.InvariantCulture,
 "{0} {1} {2} {{ {3}get; {4}set; }}",
 AccessibilityAndVirtual(Accessibility.ForProperty(navigationProperty)),
 navigationProperty.ToEndMember.RelationshipMultiplicity == RelationshipMultiplicity.Many ? ("ICollection<" + endType + ">") : endType,
 _code.Escape(navigationProperty),
 _code.SpaceAfter(Accessibility.ForGetter(navigationProperty)),
 _code.SpaceAfter(Accessibility.ForSetter(navigationProperty)));
 }

 public string AccessibilityAndVirtual(string accessibility)
 {
 return accessibility + (accessibility != "private" ? " virtual" : "");
 }

 public string EntityClassOpening(EntityType entity)
 {
 return string.Format(
 CultureInfo.InvariantCulture,
 "{0} {1}partial class {2}{3}",
 Accessibility.ForType(entity),
 _code.SpaceAfter(_code.AbstractOption(entity)),
 _code.Escape(entity),
 _code.StringBefore(" : ", _typeMapper.GetTypeName(entity.BaseType)));
 }

 public string EnumOpening(SimpleType enumType)
 {
 return string.Format(
 CultureInfo.InvariantCulture,
 "{0} enum {1} : {2}",
 Accessibility.ForType(enumType),
 _code.Escape(enumType),
 _code.Escape(_typeMapper.UnderlyingClrType(enumType)));
 }

 public void WriteFunctionParameters(EdmFunction edmFunction, Action<string, string, string, string> writeParameter)
 {
 var parameters = FunctionImportParameter.Create(edmFunction.Parameters, _code, _ef);
 foreach (var parameter in parameters.Where(p => p.NeedsLocalVariable))
 {
 var isNotNull = parameter.IsNullableOfT ? parameter.FunctionParameterName + ".HasValue" : parameter.FunctionParameterName + " != null";
 var notNullInit = "new ObjectParameter("" + parameter.EsqlParameterName + "", " + parameter.FunctionParameterName + ")";
 var nullInit = "new ObjectParameter("" + parameter.EsqlParameterName + "", typeof(" + parameter.RawClrTypeName + "))";
 writeParameter(parameter.LocalVariableName, isNotNull, notNullInit, nullInit);
 }
 }

 public string ComposableFunctionMethod(EdmFunction edmFunction, string modelNamespace)
 {
 var parameters = _typeMapper.GetParameters(edmFunction);

 return string.Format(
 CultureInfo.InvariantCulture,
 "{0} IQueryable<{1}> {2}({3})",
 AccessibilityAndVirtual(Accessibility.ForMethod(edmFunction)),
 _typeMapper.GetTypeName(_typeMapper.GetReturnType(edmFunction), modelNamespace),
 _code.Escape(edmFunction),
 string.Join(", ", parameters.Select(p => p.FunctionParameterType + " " + p.FunctionParameterName).ToArray()));
 }

 public string ComposableCreateQuery(EdmFunction edmFunction, string modelNamespace)
 {
 var parameters = _typeMapper.GetParameters(edmFunction);

 return string.Format(
 CultureInfo.InvariantCulture,
 "return ((IObjectContextAdapter)this).ObjectContext.CreateQuery<{0}>("[{1}].[{2}]({3})"{4});",
 _typeMapper.GetTypeName(_typeMapper.GetReturnType(edmFunction), modelNamespace),
 edmFunction.NamespaceName,
 edmFunction.Name,
 string.Join(", ", parameters.Select(p => "@" + p.EsqlParameterName).ToArray()),
 _code.StringBefore(", ", string.Join(", ", parameters.Select(p => p.ExecuteParameterName).ToArray())));
 }

 public string FunctionMethod(EdmFunction edmFunction, string modelNamespace, bool includeMergeOption)
 {
 var parameters = _typeMapper.GetParameters(edmFunction);
 var returnType = _typeMapper.GetReturnType(edmFunction);

var paramList = String.Join(", ", parameters.Select(p => p.FunctionParameterType + " " + p.FunctionParameterName).ToArray());
 if (includeMergeOption)
 {
 paramList = _code.StringAfter(paramList, ", ") + "MergeOption mergeOption";
 }

return string.Format(
 CultureInfo.InvariantCulture,
 "{0} {1} {2}({3})",
 AccessibilityAndVirtual(Accessibility.ForMethod(edmFunction)),
 returnType == null ? "int" : "ObjectResult<" + _typeMapper.GetTypeName(returnType, modelNamespace) + ">",
 _code.Escape(edmFunction),
 paramList);
 }

 public string ExecuteFunction(EdmFunction edmFunction, string modelNamespace, bool includeMergeOption)
 {
 var parameters = _typeMapper.GetParameters(edmFunction);
 var returnType = _typeMapper.GetReturnType(edmFunction);

var callParams = _code.StringBefore(", ", String.Join(", ", parameters.Select(p => p.ExecuteParameterName).ToArray()));
 if (includeMergeOption)
 {
 callParams = ", mergeOption" + callParams;
 }

 return string.Format(
 CultureInfo.InvariantCulture,
 "return ((IObjectContextAdapter)this).ObjectContext.ExecuteFunction{0}("{1}"{2});",
 returnType == null ? "" : "<" + _typeMapper.GetTypeName(returnType, modelNamespace) + ">",
 edmFunction.Name,
 callParams);
 }

 public string DbSet(EntitySet entitySet)
 {
 return string.Format(
 CultureInfo.InvariantCulture,
 "{0} DbSet<{1}> {2} {{ get; set; }}",
 Accessibility.ForReadOnlyProperty(entitySet),
 _typeMapper.GetTypeName(entitySet.ElementType),
 _code.Escape(entitySet));
 }

public string UsingDirectives(bool inHeader, bool includeCollections = true)
 {
 return inHeader == string.IsNullOrEmpty(_code.VsNamespaceSuggestion())
 ? string.Format(
 CultureInfo.InvariantCulture,
 "{0}using System;{1}" +
 "{2}",
 inHeader ? Environment.NewLine : "",
 includeCollections ? (Environment.NewLine + "using System.Collections.Generic;") : "",
 inHeader ? "" : Environment.NewLine)
 : "";
 }
}

public class TypeMapper
{
 private const string ExternalTypeNameAttributeName = @"http://schemas.microsoft.com/ado/2006/04/codegeneration:ExternalTypeName";

private readonly System.Collections.IList _errors;
 private readonly CodeGenerationTools _code;
 private readonly MetadataTools _ef;

public TypeMapper(CodeGenerationTools code, MetadataTools ef, System.Collections.IList errors)
 {
 ArgumentNotNull(code, "code");
 ArgumentNotNull(ef, "ef");
 ArgumentNotNull(errors, "errors");

_code = code;
 _ef = ef;
 _errors = errors;
 }

public string GetTypeName(TypeUsage typeUsage)
 {
 return typeUsage == null ? null : GetTypeName(typeUsage.EdmType, _ef.IsNullable(typeUsage), modelNamespace: null);
 }

public string GetTypeName(EdmType edmType)
 {
 return GetTypeName(edmType, isNullable: null, modelNamespace: null);
 }

public string GetTypeName(TypeUsage typeUsage, string modelNamespace)
 {
 return typeUsage == null ? null : GetTypeName(typeUsage.EdmType, _ef.IsNullable(typeUsage), modelNamespace);
 }

public string GetTypeName(EdmType edmType, string modelNamespace)
 {
 return GetTypeName(edmType, isNullable: null, modelNamespace: modelNamespace);
 }

public string GetTypeName(EdmType edmType, bool? isNullable, string modelNamespace)
 {
 if (edmType == null)
 {
 return null;
 }

var collectionType = edmType as CollectionType;
 if (collectionType != null)
 {
 return String.Format(CultureInfo.InvariantCulture, "ICollection<{0}>", GetTypeName(collectionType.TypeUsage, modelNamespace));
 }

var typeName = _code.Escape(edmType.MetadataProperties
 .Where(p => p.Name == ExternalTypeNameAttributeName)
 .Select(p => (string)p.Value)
 .FirstOrDefault())
 ?? (modelNamespace != null && edmType.NamespaceName != modelNamespace ?
 _code.CreateFullName(_code.EscapeNamespace(edmType.NamespaceName), _code.Escape(edmType)) :
 _code.Escape(edmType));

if (edmType is StructuralType)
 {
 return typeName;
 }

if (edmType is SimpleType)
 {
 var clrType = UnderlyingClrType(edmType);
 if (!IsEnumType(edmType))
 {
 typeName = _code.Escape(clrType);
 }

return clrType.IsValueType && isNullable == true ?
 String.Format(CultureInfo.InvariantCulture, "Nullable<{0}>", typeName) :
 typeName;
 }

throw new ArgumentException("edmType");
 }

 public Type UnderlyingClrType(EdmType edmType)
 {
 ArgumentNotNull(edmType, "edmType");

var primitiveType = edmType as PrimitiveType;
 if (primitiveType != null)
 {
 return primitiveType.ClrEquivalentType;
 }

if (IsEnumType(edmType))
 {
 return GetEnumUnderlyingType(edmType).ClrEquivalentType;
 }

return typeof(object);
 }

 public object GetEnumMemberValue(MetadataItem enumMember)
 {
 ArgumentNotNull(enumMember, "enumMember");

 var valueProperty = enumMember.GetType().GetProperty("Value");
 return valueProperty == null ? null : valueProperty.GetValue(enumMember, null);
 }

 public string GetEnumMemberName(MetadataItem enumMember)
 {
 ArgumentNotNull(enumMember, "enumMember");

 var nameProperty = enumMember.GetType().GetProperty("Name");
 return nameProperty == null ? null : (string)nameProperty.GetValue(enumMember, null);
 }

public System.Collections.IEnumerable GetEnumMembers(EdmType enumType)
 {
 ArgumentNotNull(enumType, "enumType");

var membersProperty = enumType.GetType().GetProperty("Members");
 return membersProperty != null
 ? (System.Collections.IEnumerable)membersProperty.GetValue(enumType, null)
 : Enumerable.Empty<MetadataItem>();
 }

 public bool EnumIsFlags(EdmType enumType)
 {
 ArgumentNotNull(enumType, "enumType");

 var isFlagsProperty = enumType.GetType().GetProperty("IsFlags");
 return isFlagsProperty != null && (bool)isFlagsProperty.GetValue(enumType, null);
 }

public bool IsEnumType(GlobalItem edmType)
 {
 ArgumentNotNull(edmType, "edmType");

return edmType.GetType().Name == "EnumType";
 }

public PrimitiveType GetEnumUnderlyingType(EdmType enumType)
 {
 ArgumentNotNull(enumType, "enumType");

return (PrimitiveType)enumType.GetType().GetProperty("UnderlyingType").GetValue(enumType, null);
 }

public string CreateLiteral(object value)
 {
 if (value == null || value.GetType() != typeof(TimeSpan))
 {
 return _code.CreateLiteral(value);
 }

return string.Format(CultureInfo.InvariantCulture, "new TimeSpan({0})", ((TimeSpan)value).Ticks);
 }

 public bool VerifyCaseInsensitiveTypeUniqueness(IEnumerable<string> types, string sourceFile)
 {
 ArgumentNotNull(types, "types");
 ArgumentNotNull(sourceFile, "sourceFile");

 var hash = new HashSet<string>(StringComparer.InvariantCultureIgnoreCase);
 if (types.Any(item => !hash.Add(item)))
 {
 _errors.Add(
 new CompilerError(sourceFile, -1, -1, "6023",
 String.Format(CultureInfo.CurrentCulture, GetResourceString("Template_CaseInsensitiveTypeConflict"))));
 return false;
 }
 return true;
 }

 public IEnumerable<SimpleType> GetEnumItemsToGenerate(IEnumerable<GlobalItem> itemCollection)
 {
 return GetItemsToGenerate<SimpleType>(itemCollection)
 .Where(e => IsEnumType(e));
 }

 public IEnumerable<T> GetItemsToGenerate<T>(IEnumerable<GlobalItem> itemCollection) where T: EdmType
 {
 return itemCollection
 .OfType<T>()
 .Where(i => !i.MetadataProperties.Any(p => p.Name == ExternalTypeNameAttributeName))
 .OrderBy(i => i.Name);
 }

public IEnumerable<string> GetAllGlobalItems(IEnumerable<GlobalItem> itemCollection)
 {
 return itemCollection
 .Where(i => i is EntityType || i is ComplexType || i is EntityContainer || IsEnumType(i))
 .Select(g => GetGlobalItemName(g));
 }

public string GetGlobalItemName(GlobalItem item)
 {
 if (item is EdmType)
 {
 return ((EdmType)item).Name;
 }
 else
 {
 return ((EntityContainer)item).Name;
 }
 }

public IEnumerable<EdmProperty> GetSimpleProperties(EntityType type)
 {
 return type.Properties.Where(p => p.TypeUsage.EdmType is SimpleType && p.DeclaringType == type);
 }

 public IEnumerable<EdmProperty> GetSimpleProperties(ComplexType type)
 {
 return type.Properties.Where(p => p.TypeUsage.EdmType is SimpleType && p.DeclaringType == type);
 }

 public IEnumerable<EdmProperty> GetComplexProperties(EntityType type)
 {
 return type.Properties.Where(p => p.TypeUsage.EdmType is ComplexType && p.DeclaringType == type);
 }

 public IEnumerable<EdmProperty> GetComplexProperties(ComplexType type)
 {
 return type.Properties.Where(p => p.TypeUsage.EdmType is ComplexType && p.DeclaringType == type);
 }

public IEnumerable<EdmProperty> GetPropertiesWithDefaultValues(EntityType type)
 {
 return type.Properties.Where(p => p.TypeUsage.EdmType is SimpleType && p.DeclaringType == type && p.DefaultValue != null);
 }

 public IEnumerable<EdmProperty> GetPropertiesWithDefaultValues(ComplexType type)
 {
 return type.Properties.Where(p => p.TypeUsage.EdmType is SimpleType && p.DeclaringType == type && p.DefaultValue != null);
 }

public IEnumerable<NavigationProperty> GetNavigationProperties(EntityType type)
 {
 return type.NavigationProperties.Where(np => np.DeclaringType == type);
 }

 public IEnumerable<NavigationProperty> GetCollectionNavigationProperties(EntityType type)
 {
 return type.NavigationProperties.Where(np => np.DeclaringType == type && np.ToEndMember.RelationshipMultiplicity == RelationshipMultiplicity.Many);
 }

 public FunctionParameter GetReturnParameter(EdmFunction edmFunction)
 {
 ArgumentNotNull(edmFunction, "edmFunction");

var returnParamsProperty = edmFunction.GetType().GetProperty("ReturnParameters");
 return returnParamsProperty == null
 ? edmFunction.ReturnParameter
 : ((IEnumerable<FunctionParameter>)returnParamsProperty.GetValue(edmFunction, null)).FirstOrDefault();
 }

public bool IsComposable(EdmFunction edmFunction)
 {
 ArgumentNotNull(edmFunction, "edmFunction");

var isComposableProperty = edmFunction.GetType().GetProperty("IsComposableAttribute");
 return isComposableProperty != null && (bool)isComposableProperty.GetValue(edmFunction, null);
 }

public IEnumerable<FunctionImportParameter> GetParameters(EdmFunction edmFunction)
 {
 return FunctionImportParameter.Create(edmFunction.Parameters, _code, _ef);
 }

public TypeUsage GetReturnType(EdmFunction edmFunction)
 {
 var returnParam = GetReturnParameter(edmFunction);
 return returnParam == null ? null : _ef.GetElementType(returnParam.TypeUsage);
 }

 public bool GenerateMergeOptionFunction(EdmFunction edmFunction, bool includeMergeOption)
 {
 var returnType = GetReturnType(edmFunction);
 return !includeMergeOption && returnType != null && returnType.EdmType.BuiltInTypeKind == BuiltInTypeKind.EntityType;
 }
}

public class EdmMetadataLoader
{
 private readonly IDynamicHost _host;
 private readonly System.Collections.IList _errors;

public EdmMetadataLoader(IDynamicHost host, System.Collections.IList errors)
 {
 ArgumentNotNull(host, "host");
 ArgumentNotNull(errors, "errors");

_host = host;
 _errors = errors;
 }

public IEnumerable<GlobalItem> CreateEdmItemCollection(string sourcePath)
 {
 ArgumentNotNull(sourcePath, "sourcePath");

if (!ValidateInputPath(sourcePath))
 {
 return new EdmItemCollection();
 }

var schemaElement = LoadRootElement(_host.ResolvePath(sourcePath));
 if (schemaElement != null)
 {
 using (var reader = schemaElement.CreateReader())
 {
 IList<EdmSchemaError> errors;
 var itemCollection = MetadataItemCollectionFactory.CreateEdmItemCollection(new[] { reader }, out errors);

ProcessErrors(errors, sourcePath);

return itemCollection;
 }
 }
 return new EdmItemCollection();
 }

public string GetModelNamespace(string sourcePath)
 {
 ArgumentNotNull(sourcePath, "sourcePath");

if (!ValidateInputPath(sourcePath))
 {
 return string.Empty;
 }

var model = LoadRootElement(_host.ResolvePath(sourcePath));
 if (model == null)
 {
 return string.Empty;
 }

var attribute = model.Attribute("Namespace");
 return attribute != null ? attribute.Value : "";
 }

private bool ValidateInputPath(string sourcePath)
 {
 if (sourcePath == "$" + "edmxInputFile" + "$")
 {
 _errors.Add(
 new CompilerError(_host.TemplateFile ?? sourcePath, 0, 0, string.Empty,
 GetResourceString("Template_ReplaceVsItemTemplateToken")));
 return false;
 }

return true;
 }

public XElement LoadRootElement(string sourcePath)
 {
 ArgumentNotNull(sourcePath, "sourcePath");

var root = XElement.Load(sourcePath, LoadOptions.SetBaseUri | LoadOptions.SetLineInfo);
 return root.Elements()
 .Where(e => e.Name.LocalName == "Runtime")
 .Elements()
 .Where(e => e.Name.LocalName == "ConceptualModels")
 .Elements()
 .Where(e => e.Name.LocalName == "Schema")
 .FirstOrDefault()
 ?? root;
 }

private void ProcessErrors(IEnumerable<EdmSchemaError> errors, string sourceFilePath)
 {
 foreach (var error in errors)
 {
 _errors.Add(
 new CompilerError(
 error.SchemaLocation ?? sourceFilePath,
 error.Line,
 error.Column,
 error.ErrorCode.ToString(CultureInfo.InvariantCulture),
 error.Message)
 {
 IsWarning = error.Severity == EdmSchemaErrorSeverity.Warning
 });
 }
 }

 public bool IsLazyLoadingEnabled(EntityContainer container)
 {
 string lazyLoadingAttributeValue;
 var lazyLoadingAttributeName = MetadataConstants.EDM_ANNOTATION_09_02 + ":LazyLoadingEnabled";
 bool isLazyLoading;
 return !MetadataTools.TryGetStringMetadataPropertySetting(container, lazyLoadingAttributeName, out lazyLoadingAttributeValue)
 || !bool.TryParse(lazyLoadingAttributeValue, out isLazyLoading)
 || isLazyLoading;
 }
}

public static void ArgumentNotNull<T>(T arg, string name) where T : class
{
 if (arg == null)
 {
 throw new ArgumentNullException(name);
 }
}

private static readonly Lazy<System.Resources.ResourceManager> ResourceManager =
 new Lazy<System.Resources.ResourceManager>(
 () => new System.Resources.ResourceManager("System.Data.Entity.Design", typeof(MetadataItemCollectionFactory).Assembly), isThreadSafe: true);

public static string GetResourceString(string resourceName)
{
 ArgumentNotNull(resourceName, "resourceName");

return ResourceManager.Value.GetString(resourceName, null);
}

#>

 

In the next section we will take a look at the output of this template.

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OData Using C#, MVC, WebAPI, Entity Framework, Dependency Injection (DI)/Inversion of Control (IoC) and Kendo UI

OData – Displaying Hierarchical Data with Kendo UI, MVC and a Queryable Entity Framework Repository

It is recommended that you are proficient with using .Net, dependency injection, MVC, Fiddler, and SQL Server Profiler – ie. good debugging skills, and can use the Kendo UI Grid extension for data display purposes. Otherwise, you can access the OData URL paths for viewing the raw data.

Introduction

As a part of this solution I created a generic queryable repository that I accessed Entity Framework Database First Entities through a repository and unit of work pattern: DOWNLOAD.

To modify your *.tt template to output a compatible context class, see the following article: Modifying Entity Framework for use by a Repository and Unit of Work Pattern

The starting point for this article was a requirement for a new UI POC, for which Kendo UI (http://www.kendoui.com/) was chosen. An existing SQL database was used as a data source and a RESTful OData (http://www.odata.org/) API endpoint was created for data access.

Explaining how to setup Kendo UI and what OData is are out of scope for this article.

The purpose of this article is to identify a clean-cut way of using OData and hierarchical data. One of the most commonly asked questions is, “How do I only return the rows needed from my database server, and not 100,000 records then filter?” (or variations there-of). This article will identify how to accomplish this.

We are using OData because it represents an efficient way of retrieving data, as requested directly from the client, without having to write specific associated controller action methods for things like paging and filtering.

For reads, the client sends query parameters that are received by a single Get() method. The query options are then handled on the server, and can be passed directly through to SQL Server (in this case, through Entity Framework).

All CRUD operations are quite simple through OData as well, but are out of scope of this article (other than Reads).

Note:  If you don’t want to use Dependency Injection, and the generic repository included – simply use Entity Framework directly, I include a controller action method at the end of this article that allows you to do this.

Background

The basis for any data-driven application is the DAL, and it’s important to know how the data is accessed and make sure it is done efficiently, as such, I have worked on several projects including rewriting a popular ORM to make use of SQL Server’s TVP’s (http://subsonic23tvp.codeplex.com/).

I am always cautious when controls automatically “do things”, especially when it comes to data access.

I initially setup a Kendo UI Grid with a details grid containing users. Everything looked fine – I expanded a group, and was able to navigate through a list of associated users.

In using the browser console and SQL Server Profiler, I noticed that all users were being returned from SQL Server, then filtering occurring before it reached the client.

In another attempt, I noticed that all records were returned to the client, an the control was paging through the entire data set.

What I wanted to see was that SQL Server was only returning, say 10 records at a time and applying the filtering options.

For this article I am using and making reference to two tables USERS and USERGROUPS. Use this article as a reference for your own data sets.

I typically put a lot of comments in my code to help others understand exactly what’s going on. These comments usually include some alternate examples and helpful URLs for additional background details.

Not everything is described in the text of this article, and most-likely some of your questions will be answered by actually reading through the code itself – highly recommend it.

Solution Setup

The ATMS.DAL project contains the auto-generated classes through Entity Framework Database First.

Here is what the basic solution structure looks like:

odata-solution1

Next, we see the differences between our two sets of control classes – we have two sets:

odata-solution2

We will be using Entity Framework Database First to generate our database entities. However, for testability, we will first use a generic repository pattern and dependency injection / IoC to access our entities through EF.

Explaining how this works and why it is important is out of scope of this article, but I have included the Repository project as a part of the article’s code. The Repository uses generics and as such is not tightly-coupled on either end. Use freely as needed.

The repository project can be added to any .Net solution and referenced in your associated projects.

Simple Injector (http://simpleinjector.codeplex.com/) was used for our DI container, which can be added through a Nuget package to your solution.