[Entity Framework 6] DB First - Create Metadata class and services with T4

 C#   Entity Framework   Code-first

▌Introduction

---

This articles was inspired by WASICHRIS’ article:

[Entity Framework] 利用T4快速建立Entity Data Model之MetaData類別

Since I have a UOW (Unit of work) pattern on my Entity Framework 6 library, every POCO entity should inherits the base entity class and has its own CRUD service class as following,

PS. We need to create a Partial class which inherits UowEntity in DB-first.

However the time for creating the Partial classes and Service classes for a whole new DB-first data model (ADO.NET Entity Data Model) is expensive, so that we will use T4 to generate them automatically.

▋Related articles

[Entity Framework 6] Use MetadataType to define the attribure of DAO properties

[Visual Studio 2015] Create and distribute a Poject Template with Wizard (1)

[Visual Studio 2015] Create and distribute a Poject Template with Wizard (2)

▌Environment

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▋Visual Studio 2017 community

▋Entity Framework 6.1.3

▌Implement

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▋T4 for Models

OK, the code is complex and I won’t give too much explanation on it.

The flow is,

1.  Load .edmx and get all entity types (EntityType) from it

2.  For every EntityType, generate a .cs file with same class name (if not exists)

3.  Write namespaces and partial class structure into the .cs file

Gist for EdmxModel-metadata.tt

	<#@ template language="C#" debug="true" hostspecific="true"#>
	<#@ assembly name="System.Core" #>
	<#@ import namespace="System.IO" #>
	<#@ import namespace="System.Diagnostics" #>
	<#@ import namespace="System.Linq" #>
	<#@ import namespace="System.Text" #>
	<#@ import namespace="System.Text.RegularExpressions" #>
	<#@ import namespace="System.Collections.Generic" #>
	<#@ include file="EF.Utility.CS.ttinclude"#>
	<#@ output extension=".cs" #>
	<#
	// Formatting helper for code
	CodeGenerationTools code = new CodeGenerationTools(this);
	// object for creating entity information
	MetadataLoader loader = new MetadataLoader(this);
	// TODO: NEED TO PROVIDE EDMX FILE LOCATION
	string inputFile = string.Empty;
	var currentPath = this.Host.ResolvePath("");
	string[] files = System.IO.Directory.GetFiles(currentPath, "*.edmx");
	if(files==null || files.Length <=0)
	return string.Empty;
	else
	inputFile = files[0];
	// File generation suffix
	string suffix = "Metadata";
	// Meta data information for the conceptual model
	EdmItemCollection ItemCollection = loader.CreateEdmItemCollection(inputFile);
	// Suggested namespace
	string namespaceName = code.VsNamespaceSuggestion();// + suffix;
	// File generator according to different section
	EntityFrameworkTemplateFileManager fileManager =
	EntityFrameworkTemplateFileManager.Create(this);
	// Loop through each entity type
	foreach (EntityType entity in
	ItemCollection.GetItems<EntityType>().OrderBy(e => e.Name))
	{
	// File name for data annotation file
	string fileName = entity.Name + suffix + ".cs";
	// Check for file existence, If it does not
	// exist create new file for data annotation
	if (!DoesFileExist(fileName))
	{
	// Header for file
	writeHeader(fileManager);
	// Create new file
	fileManager.StartNewFile(fileName);
	// Add namespaces into file
	BeginNamespace(namespaceName, code);
	#>
	/// <summary>
	/// <#=code.Escape(entity)#> class
	/// </summary>
	[Description("<#=GetFriendlyName(code.Escape(entity))#>")]
	[MetadataType(typeof(<#=code.Escape(entity) + suffix#>))]
	<#= Accessibility.ForType(entity)#> <#=code.SpaceAfter(code.AbstractOption(entity))#> partial class <#=code.Escape(entity)#> : UowEntity
	{
	}
	/// <summary>
	/// <#=code.Escape(entity)#> Metadata class
	/// </summary>
	internal <#=code.SpaceAfter(code.AbstractOption(entity))#> class <#=code.Escape(entity) + suffix#>
	{
	<#
	// Loop through each primitive property of entity
	foreach (EdmProperty edmProperty in entity.Properties.Where(p =>
	p.TypeUsage.EdmType is PrimitiveType && p.DeclaringType == entity))
	{
	#>
	<#= CodeRegion.GetIndent(1) #>
	/// <summary>
	/// <#=GetFriendlyName(code.Escape(edmProperty))#>
	/// </summary>
	<#
	// Write display name data annotation
	writeDisplayName(edmProperty);
	// Write description data annotation
	writeDescriptionAttribute(edmProperty);
	// Write required field data annotation
	writeRequiredAttribute(edmProperty);
	// Write string length annotation
	writeStringLengthAttribute(edmProperty);
	#>
	<#=Accessibility.ForProperty(edmProperty)#> <#=code.Escape(edmProperty.TypeUsage)#> <#=code.Escape(edmProperty)#> { <#=Accessibility.ForGetter(edmProperty)#>get; <#=Accessibility.ForSetter(edmProperty)#>set; }
	<#
	}
	#>
	<#= CodeRegion.GetIndent(1) #>
	}
	<#
	// End namespace
	EndNamespace(namespaceName);
	}
	else
	{
	// Write with original file
	fileManager.StartNewFile(fileName);
	this.Write(OutputFile(fileName));
	}
	}
	fileManager.Process();
	#>
	<#+
	// Write display name data annotation
	void writeDisplayName(EdmProperty edmProperty) {
	string displayName = edmProperty.Name;
	// Check for property name
	if (!string.IsNullOrEmpty(displayName))
	{
	// Generate user friendly name
	displayName = GetFriendlyName(edmProperty.Name);
	// Populate actual string to be written
	WriteLine("{0}[DisplayName(\"{1}\")]", CodeRegion.GetIndent(1), displayName);
	}
	}
	//Write description attribute
	void writeDescriptionAttribute(EdmProperty edmProperty) {
	string displayName = edmProperty.Name; //Use Name as description
	// Check for property name
	if (!string.IsNullOrEmpty(displayName))
	{
	// Generate user friendly name
	displayName = GetFriendlyName(edmProperty.Name);
	// Populate actual string to be written
	WriteLine("{0}[Description(\"{1}\")]", CodeRegion.GetIndent(1), displayName);
	}
	}
	//Write required attribute
	void writeRequiredAttribute(EdmProperty edmProperty) {
	// Check for required property
	if (!edmProperty.Nullable)
	{
	WriteLine("{0}[Required(ErrorMessage = \"{1} is required\")]",
	CodeRegion.GetIndent(2),GetFriendlyName(edmProperty.Name));
	}
	}
	//Write max string length
	void writeStringLengthAttribute(EdmProperty edmProperty) {
	// Object for retrieving additional information from property
	Facet maxLengthfacet;
	// Try to get max length from property
	if (edmProperty.TypeUsage.Facets.TryGetValue("MaxLength", true, out maxLengthfacet))
	{
	// Max length for property
	double lengthAttribute;
	// Try to parse max length value
	if (double.TryParse(maxLengthfacet.Value.ToString(), out lengthAttribute))
	{
	// Generate actual string for attribute
	WriteLine("{0}[MaxLength({1}, ErrorMessage = \"{2} cannot " +
	"be longer than {1} characters\")]",
	CodeRegion.GetIndent(2),lengthAttribute,GetFriendlyName(edmProperty.Name));
	}
	}
	}
	// Initialize header
	void writeHeader(EntityFrameworkTemplateFileManager fileManager, params string[] extraUsings)
	{
	fileManager.StartHeader();
	#>
	using System;
	using System.ComponentModel;
	using System.ComponentModel.DataAnnotations;
	using JB.Infra.Util.EF.Entity;
	<#=String.Join(String.Empty, extraUsings.Select(u => "using " + u + ";" + Environment.NewLine).ToArray())#>
	<#+
	fileManager.EndBlock();
	}
	// Add namespace
	void BeginNamespace(string namespaceName, CodeGenerationTools code)
	{
	// Generate region
	CodeRegion region = new CodeRegion(this);
	// Check for namespace value
	if (!String.IsNullOrEmpty(namespaceName))
	{
	#>
	namespace <#=code.EscapeNamespace(namespaceName)#>
	{
	<#+
	// Add indent
	PushIndent(CodeRegion.GetIndent(1));
	}
	}
	// End namespace
	void EndNamespace(string namespaceName)
	{
	if (!String.IsNullOrEmpty(namespaceName))
	{
	PopIndent();
	#>
	}
	<#+
	}
	}
	#>
	<#+
	// Check for file existence
	bool DoesFileExist(string filename)
	{
	return File.Exists(Path.Combine(GetCurrentDirectory(),filename));
	}
	// Get current folder directory
	string GetCurrentDirectory()
	{
	return System.IO.Path.GetDirectoryName(this.Host.TemplateFile);
	}
	// Get content of file name
	string OutputFile(string filename)
	{
	using(StreamReader sr =
	new StreamReader(Path.Combine(GetCurrentDirectory(),filename)))
	{
	return sr.ReadToEnd();
	}
	}
	// Get friendly name for property names
	string GetFriendlyName(string value)
	{
	return Regex.Replace(value,
	"([A-Z]+)", " $1",
	RegexOptions.Compiled).Trim();
	}
	#>

view raw EdmxModel-metadata.tt hosted with ❤ by GitHub

Gist for EdmxModel-simple.tt

	<#@ template language="C#" debug="true" hostspecific="true"#>
	<#@ assembly name="System.Core" #>
	<#@ import namespace="System.IO" #>
	<#@ import namespace="System.Diagnostics" #>
	<#@ import namespace="System.Linq" #>
	<#@ import namespace="System.Text" #>
	<#@ import namespace="System.Text.RegularExpressions" #>
	<#@ import namespace="System.Collections.Generic" #>
	<#@ include file="EF.Utility.CS.ttinclude"#>
	<#@ output extension=".cs" #>
	<#
	// Formatting helper for code
	CodeGenerationTools code = new CodeGenerationTools(this);
	// object for creating entity information
	MetadataLoader loader = new MetadataLoader(this);
	// TODO: NEED TO PROVIDE EDMX FILE LOCATION
	string inputFile = string.Empty;
	var currentPath = this.Host.ResolvePath("");
	string[] files = System.IO.Directory.GetFiles(currentPath, "*.edmx");
	if(files==null || files.Length <=0)
	return string.Empty;
	else
	inputFile = files[0];
	// File generation suffix
	string suffix = "Metadata";
	// Meta data information for the conceptual model
	EdmItemCollection ItemCollection = loader.CreateEdmItemCollection(inputFile);
	// Suggested namespace
	string namespaceName = code.VsNamespaceSuggestion();// + suffix;
	// File generator according to different section
	EntityFrameworkTemplateFileManager fileManager =
	EntityFrameworkTemplateFileManager.Create(this);
	// Loop through each entity type
	foreach (EntityType entity in
	ItemCollection.GetItems<EntityType>().OrderBy(e => e.Name))
	{
	// File name for data annotation file
	string fileName = entity.Name + suffix + ".cs";
	// Check for file existence, If it does not
	// exist create new file for data annotation
	if (!DoesFileExist(fileName))
	{
	// Header for file
	writeHeader(fileManager);
	// Create new file
	fileManager.StartNewFile(fileName);
	// Add namespaces into file
	BeginNamespace(namespaceName, code);
	#>
	/// <summary>
	/// <#=code.Escape(entity)#> class
	/// </summary>
	[Description("<#=GetFriendlyName(code.Escape(entity))#>")]
	<#= Accessibility.ForType(entity)#> <#=code.SpaceAfter(code.AbstractOption(entity))#> partial class <#=code.Escape(entity)#> : UowEntity
	{
	}
	<#
	// End namespace
	EndNamespace(namespaceName);
	}
	else
	{
	// Write with original file
	fileManager.StartNewFile(fileName);
	this.Write(OutputFile(fileName));
	}
	}
	fileManager.Process();
	#>
	<#+
	// Write display name data annotation
	void writeDisplayName(EdmProperty edmProperty) {
	string displayName = edmProperty.Name;
	// Check for property name
	if (!string.IsNullOrEmpty(displayName))
	{
	// Generate user friendly name
	displayName = GetFriendlyName(edmProperty.Name);
	// Populate actual string to be written
	WriteLine("{0}[DisplayName(\"{1}\")]", CodeRegion.GetIndent(1), displayName);
	}
	}
	//Write description attribute
	void writeDescriptionAttribute(EdmProperty edmProperty) {
	string displayName = edmProperty.Name; //Use Name as description
	// Check for property name
	if (!string.IsNullOrEmpty(displayName))
	{
	// Generate user friendly name
	displayName = GetFriendlyName(edmProperty.Name);
	// Populate actual string to be written
	WriteLine("{0}[Description(\"{1}\")]", CodeRegion.GetIndent(1), displayName);
	}
	}
	//Write required attribute
	void writeRequiredAttribute(EdmProperty edmProperty) {
	// Check for required property
	if (!edmProperty.Nullable)
	{
	WriteLine("{0}[Required(ErrorMessage = \"{1} is required\")]",
	CodeRegion.GetIndent(2),GetFriendlyName(edmProperty.Name));
	}
	}
	//Write max string length
	void writeStringLengthAttribute(EdmProperty edmProperty) {
	// Object for retrieving additional information from property
	Facet maxLengthfacet;
	// Try to get max length from property
	if (edmProperty.TypeUsage.Facets.TryGetValue("MaxLength", true, out maxLengthfacet))
	{
	// Max length for property
	double lengthAttribute;
	// Try to parse max length value
	if (double.TryParse(maxLengthfacet.Value.ToString(), out lengthAttribute))
	{
	// Generate actual string for attribute
	WriteLine("{0}[MaxLength({1}, ErrorMessage = \"{2} cannot " +
	"be longer than {1} characters\")]",
	CodeRegion.GetIndent(2),lengthAttribute,GetFriendlyName(edmProperty.Name));
	}
	}
	}
	// Initialize header
	void writeHeader(EntityFrameworkTemplateFileManager fileManager, params string[] extraUsings)
	{
	fileManager.StartHeader();
	#>
	using System;
	using System.ComponentModel;
	using System.ComponentModel.DataAnnotations;
	using JB.Infra.Util.EF.Entity;
	<#=String.Join(String.Empty, extraUsings.Select(u => "using " + u + ";" + Environment.NewLine).ToArray())#>
	<#+
	fileManager.EndBlock();
	}
	// Add namespace
	void BeginNamespace(string namespaceName, CodeGenerationTools code)
	{
	// Generate region
	CodeRegion region = new CodeRegion(this);
	// Check for namespace value
	if (!String.IsNullOrEmpty(namespaceName))
	{
	#>
	namespace <#=code.EscapeNamespace(namespaceName)#>
	{
	<#+
	// Add indent
	PushIndent(CodeRegion.GetIndent(1));
	}
	}
	// End namespace
	void EndNamespace(string namespaceName)
	{
	if (!String.IsNullOrEmpty(namespaceName))
	{
	PopIndent();
	#>
	}
	<#+
	}
	}
	#>
	<#+
	// Check for file existence
	bool DoesFileExist(string filename)
	{
	return File.Exists(Path.Combine(GetCurrentDirectory(),filename));
	}
	// Get current folder directory
	string GetCurrentDirectory()
	{
	return System.IO.Path.GetDirectoryName(this.Host.TemplateFile);
	}
	// Get content of file name
	string OutputFile(string filename)
	{
	using(StreamReader sr =
	new StreamReader(Path.Combine(GetCurrentDirectory(),filename)))
	{
	return sr.ReadToEnd();
	}
	}
	// Get friendly name for property names
	string GetFriendlyName(string value)
	{
	return Regex.Replace(value,
	"([A-Z]+)", " $1",
	RegexOptions.Compiled).Trim();
	}
	#>

view raw EdmxModel-uow.tt hosted with ❤ by GitHub

The difference between EdmxModel-metadata.tt and EdmxModel-simple.tt:

1.   The partial class created from EdmxModel-metadata.tt inherits UowEntity and defines the MetadataType

2.   The partial class created from EdmxModel-simple.tt only inherits UowEntity

Assume that there is a POCO: MyModel in EDMX, the above T4 will generate:

1.  MyModels.cs (by EdmxModel-simple.tt)

2.  MyModelsMetadata.cs (by EdmxModel-metadata.tt)

And their contents:

▋MyModels.cs

namespace JB.Infra.Util.EF.Models

{

    using System;

    using System.Collections.Generic;

   

    public partial class MyModels

    {

        public int Id { get; set; }

        public string Name { get; set; }

        public string Department { get; set; }

    }

}

▋MyModelsMetadata.cs

using System;

using System.ComponentModel;

using System.ComponentModel.DataAnnotations;

using JB.Infra.Util.EF.Entity;

namespace JB.Infra.Utility.EF.DbFirst.UnitTest.Models

{

    /// <summary>

    /// MyModels class

    /// </summary>

    [Description("My Models")]

    [MetadataType(typeof(MyModelsMetadata))]

    public partial class MyModels : UowEntity

    {

    }

    /// <summary>

    /// MyModels Metadata class

    /// </summary>

    internal class MyModelsMetadata

    {

        /// <summary>

        /// Id

        /// </summary>       

        [DisplayName("Id")]

        [Description("Id")]

        [Required(ErrorMessage = "Id is required")]

        public int Id { get; set; }

        /// skip ...

▋T4 for Services

Same process on generating CRUD Service class.

Notice the relative path of .edmx is updated to “../Models”

Gist for EdmxService.tt

	<#@ template language="C#" debug="true" hostspecific="true"#>
	<#@ assembly name="System.Core" #>
	<#@ import namespace="System.IO" #>
	<#@ import namespace="System.Diagnostics" #>
	<#@ import namespace="System.Linq" #>
	<#@ import namespace="System.Text" #>
	<#@ import namespace="System.Text.RegularExpressions" #>
	<#@ import namespace="System.Collections.Generic" #>
	<#@ include file="EF.Utility.CS.ttinclude"#>
	<#@ output extension=".cs" #>
	<#
	// Formatting helper for code
	CodeGenerationTools code = new CodeGenerationTools(this);
	// object for creating entity information
	MetadataLoader loader = new MetadataLoader(this);
	// TODO: NEED TO PROVIDE EDMX FILE LOCATION
	string inputFile = string.Empty;
	var currentPath = this.Host.ResolvePath("../Models");
	string[] files = System.IO.Directory.GetFiles(currentPath, "*.edmx");
	if(files==null || files.Length <=0)
	return string.Empty;
	else
	inputFile = files[0];
	// File generation suffix
	string suffix = "Service";
	// Meta data information for the conceptual model
	EdmItemCollection ItemCollection = loader.CreateEdmItemCollection(inputFile);
	// Suggested namespace
	string namespaceName = code.VsNamespaceSuggestion();// + suffix;
	// File generator according to different section
	EntityFrameworkTemplateFileManager fileManager =
	EntityFrameworkTemplateFileManager.Create(this);
	// Loop through each entity type
	foreach (EntityType entity in
	ItemCollection.GetItems<EntityType>().OrderBy(e => e.Name))
	{
	// File name for data annotation file
	string fileName = entity.Name + suffix + ".cs";
	// Check for file existence, If it does not
	// exist create new file for data annotation
	if (!DoesFileExist(fileName))
	{
	// Header for file
	string modelNamespace= string.Concat(code.EscapeNamespace(namespaceName).ToString().Replace(".Service",".Models"));
	writeHeader(fileManager, modelNamespace);
	// Create new file
	fileManager.StartNewFile(fileName);
	// Add namespaces into file
	BeginNamespace(namespaceName, code);
	#>
	/// <summary>
	/// <#=code.Escape(entity)#> Service
	/// </summary>
	<#=Accessibility.ForType(entity)#> class <#=code.Escape(entity)#>Service<T> : JB.Infra.Util.EF.Service.BaseDalService<T> where T : <#=code.Escape(entity)#>
	{
	public <#=code.Escape(entity)#>Service(DbContext dbContext):base(dbContext)
	{
	}
	}
	<#
	// End namespace
	EndNamespace(namespaceName);
	}
	else
	{
	// Write with original file
	fileManager.StartNewFile(fileName);
	this.Write(OutputFile(fileName));
	}
	}
	fileManager.Process();
	#>
	<#+
	// Initialize header
	void writeHeader(EntityFrameworkTemplateFileManager fileManager, params string[] extraUsings)
	{
	fileManager.StartHeader();
	#>
	using System.Data.Entity;
	<#=String.Join(String.Empty, extraUsings.Select(u => "using " + u + ";" + Environment.NewLine).ToArray())#>
	<#+
	fileManager.EndBlock();
	}
	// Add namespace
	void BeginNamespace(string namespaceName, CodeGenerationTools code)
	{
	// Generate region
	CodeRegion region = new CodeRegion(this);
	// Check for namespace value
	if (!String.IsNullOrEmpty(namespaceName))
	{
	#>
	namespace <#=code.EscapeNamespace(namespaceName)#>
	{
	<#+
	// Add indent
	PushIndent(CodeRegion.GetIndent(1));
	}
	}
	// End namespace
	void EndNamespace(string namespaceName)
	{
	if (!String.IsNullOrEmpty(namespaceName))
	{
	PopIndent();
	#>
	}
	<#+
	}
	}
	#>
	<#+
	// Check for file existence
	bool DoesFileExist(string filename)
	{
	return File.Exists(Path.Combine(GetCurrentDirectory(),filename));
	}
	// Get current folder directory
	string GetCurrentDirectory()
	{
	return System.IO.Path.GetDirectoryName(this.Host.TemplateFile);
	}
	// Get content of file name
	string OutputFile(string filename)
	{
	using(StreamReader sr =
	new StreamReader(Path.Combine(GetCurrentDirectory(),filename)))
	{
	return sr.ReadToEnd();
	}
	}
	// Get friendly name for property names
	string GetFriendlyName(string value)
	{
	return Regex.Replace(value,
	"([A-Z]+)", " $1",
	RegexOptions.Compiled).Trim();
	}
	#>

view raw EdmxService-uow.tt hosted with ❤ by GitHub

Result:

▌Reference

---

▋ [Entity Framework] 利用T4快速建立Entity Data Model之MetaData類別