我首先使用Entity Framework 4.3.1代码进行显式迁移。如何在实体配置类或迁移中添加列的描述，以便最终作为SQL Server中列的描述（例如2008 R2）？
我知道我可以编写一个DbMigration类的扩展方法，它将sp_updateextendedproperty或sp_addextendedproperty过程调用注册为迁移事务中的sql迁移操作并调用该扩展在迁移Up方法中创建表之后。但是，我还没有发现一种优雅的内置方式吗？很高兴拥有一个迁移变更检测逻辑可以获取的属性，并在scaffolded迁移中生成appropritate方法调用。
答案 0 :(得分：14)
我也需要这个。所以我花了一天时间在这里：
守则
public class DbDescriptionUpdater<TContext>
where TContext : System.Data.Entity.DbContext
{
public DbDescriptionUpdater(TContext context)
{
this.context = context;
}
Type contextType;
TContext context;
DbTransaction transaction;
public void UpdateDatabaseDescriptions()
{
contextType = typeof(TContext);
this.context = context;
var props = contextType.GetProperties(System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.Public);
transaction = null;
try
{
context.Database.Connection.Open();
transaction = context.Database.Connection.BeginTransaction();
foreach (var prop in props)
{
if (prop.PropertyType.InheritsOrImplements((typeof(DbSet<>))))
{
var tableType = prop.PropertyType.GetGenericArguments()[0];
SetTableDescriptions(tableType);
}
}
transaction.Commit();
}
catch
{
if (transaction != null)
transaction.Rollback();
throw;
}
finally
{
if (context.Database.Connection.State == System.Data.ConnectionState.Open)
context.Database.Connection.Close();
}
}
private void SetTableDescriptions(Type tableType)
{
string fullTableName = context.GetTableName(tableType);
Regex regex = new Regex(@"(\[\w+\]\.)?\[(?<table>.*)\]");
Match match = regex.Match(fullTableName);
string tableName;
if (match.Success)
tableName = match.Groups["table"].Value;
else
tableName = fullTableName;
var tableAttrs = tableType.GetCustomAttributes(typeof(TableAttribute), false);
if (tableAttrs.Length > 0)
tableName = ((TableAttribute)tableAttrs[0]).Name;
foreach (var prop in tableType.GetProperties(System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance))
{
if (prop.PropertyType.IsClass && prop.PropertyType != typeof(string))
continue;
var attrs = prop.GetCustomAttributes(typeof(DisplayAttribute), false);
if (attrs.Length > 0)
SetColumnDescription(tableName, prop.Name, ((DisplayAttribute)attrs[0]).Name);
}
}
private void SetColumnDescription(string tableName, string columnName, string description)
{
string strGetDesc = "select [value] from fn_listextendedproperty('MS_Description','schema','dbo','table',N'" + tableName + "','column',null) where objname = N'" + columnName + "';";
var prevDesc = RunSqlScalar(strGetDesc);
if (prevDesc == null)
{
RunSql(@"EXEC sp_addextendedproperty
@name = N'MS_Description', @value = @desc,
@level0type = N'Schema', @level0name = 'dbo',
@level1type = N'Table', @level1name = @table,
@level2type = N'Column', @level2name = @column;",
new SqlParameter("@table", tableName),
new SqlParameter("@column", columnName),
new SqlParameter("@desc", description));
}
else
{
RunSql(@"EXEC sp_updateextendedproperty
@name = N'MS_Description', @value = @desc,
@level0type = N'Schema', @level0name = 'dbo',
@level1type = N'Table', @level1name = @table,
@level2type = N'Column', @level2name = @column;",
new SqlParameter("@table", tableName),
new SqlParameter("@column", columnName),
new SqlParameter("@desc", description));
}
}
DbCommand CreateCommand(string cmdText, params SqlParameter[] parameters)
{
var cmd = context.Database.Connection.CreateCommand();
cmd.CommandText = cmdText;
cmd.Transaction = transaction;
foreach (var p in parameters)
cmd.Parameters.Add(p);
return cmd;
}
void RunSql(string cmdText, params SqlParameter[] parameters)
{
var cmd = CreateCommand(cmdText, parameters);
cmd.ExecuteNonQuery();
}
object RunSqlScalar(string cmdText, params SqlParameter[] parameters)
{
var cmd = CreateCommand(cmdText, parameters);
return cmd.ExecuteScalar();
}
}
public static class ReflectionUtil
{
public static bool InheritsOrImplements(this Type child, Type parent)
{
parent = ResolveGenericTypeDefinition(parent);
var currentChild = child.IsGenericType
? child.GetGenericTypeDefinition()
: child;
while (currentChild != typeof(object))
{
if (parent == currentChild || HasAnyInterfaces(parent, currentChild))
return true;
currentChild = currentChild.BaseType != null
&& currentChild.BaseType.IsGenericType
? currentChild.BaseType.GetGenericTypeDefinition()
: currentChild.BaseType;
if (currentChild == null)
return false;
}
return false;
}
private static bool HasAnyInterfaces(Type parent, Type child)
{
return child.GetInterfaces()
.Any(childInterface =>
{
var currentInterface = childInterface.IsGenericType
? childInterface.GetGenericTypeDefinition()
: childInterface;
return currentInterface == parent;
});
}
private static Type ResolveGenericTypeDefinition(Type parent)
{
var shouldUseGenericType = true;
if (parent.IsGenericType && parent.GetGenericTypeDefinition() != parent)
shouldUseGenericType = false;
if (parent.IsGenericType && shouldUseGenericType)
parent = parent.GetGenericTypeDefinition();
return parent;
}
}
public static class ContextExtensions
{
public static string GetTableName(this DbContext context, Type tableType)
{
MethodInfo method = typeof(ContextExtensions).GetMethod("GetTableName", new Type[] { typeof(DbContext) })
.MakeGenericMethod(new Type[] { tableType });
return (string)method.Invoke(context, new object[] { context });
}
public static string GetTableName<T>(this DbContext context) where T : class
{
ObjectContext objectContext = ((IObjectContextAdapter)context).ObjectContext;
return objectContext.GetTableName<T>();
}
public static string GetTableName<T>(this ObjectContext context) where T : class
{
string sql = context.CreateObjectSet<T>().ToTraceString();
Regex regex = new Regex("FROM (?<table>.*) AS");
Match match = regex.Match(sql);
string table = match.Groups["table"].Value;
return table;
}
}
如何使用
在Migrations/Configuration.cs文件中，在Seed方法的末尾添加：
DbDescriptionUpdater<ContextClass> updater = new DbDescriptionUpdater<ContextClass>(context);
updater.UpdateDatabaseDescriptions();
然后在包管理器控制台中键入update-database并按Enter键。
就是这样。
代码使用实体类属性上的[Display(Name="Description here")]属性来设置描述。
请报告任何错误或建议改进。
感谢
我已经使用过其他人的这些代码了，我想说谢谢：
Check if a class is derived from a generic class
答案 1 :(得分：7)
注意对当前的答案非常满意（但是工作的道具！），我想要一种方法来拉取我的类中的现有注释标记而不是使用属性。在我看来，我不知道微软为什么不支持这个，因为它显然应该存在！
首先，打开XML Documentation文件：Project Properties-＆gt; Build-＆gt; XML文档文件 - ＆gt; App_Data \ YourProjectName.XML
其次，将文件包含为嵌入式资源。构建项目，转到App_Data，显示隐藏文件并包含生成的XML文件。选择嵌入式资源和复制如果更新（这是可选的，您可以明确指定路径，但在我看来这是更清洁）。请注意，您必须使用此方法，因为程序集中不存在标记，这将使您无法找到存储XML的位置。
以下是代码实现，它是已接受答案的修改版本：
public class SchemaDescriptionUpdater<TContext> where TContext : DbContext
{
Type contextType;
TContext context;
DbTransaction transaction;
XmlAnnotationReader reader;
public SchemaDescriptionUpdater(TContext context)
{
this.context = context;
reader = new XmlAnnotationReader();
}
public SchemaDescriptionUpdater(TContext context, string xmlDocumentationPath)
{
this.context = context;
reader = new XmlAnnotationReader(xmlDocumentationPath);
}
public void UpdateDatabaseDescriptions()
{
contextType = typeof(TContext);
var props = contextType.GetProperties(System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.Public);
transaction = null;
try
{
context.Database.Connection.Open();
transaction = context.Database.Connection.BeginTransaction();
foreach (var prop in props)
{
if (prop.PropertyType.InheritsOrImplements((typeof(DbSet<>))))
{
var tableType = prop.PropertyType.GetGenericArguments()[0];
SetTableDescriptions(tableType);
}
}
transaction.Commit();
}
catch
{
if (transaction != null)
transaction.Rollback();
throw;
}
finally
{
if (context.Database.Connection.State == System.Data.ConnectionState.Open)
context.Database.Connection.Close();
}
}
private void SetTableDescriptions(Type tableType)
{
string fullTableName = context.GetTableName(tableType);
Regex regex = new Regex(@"(\[\w+\]\.)?\[(?<table>.*)\]");
Match match = regex.Match(fullTableName);
string tableName;
if (match.Success)
tableName = match.Groups["table"].Value;
else
tableName = fullTableName;
var tableAttrs = tableType.GetCustomAttributes(typeof(TableAttribute), false);
if (tableAttrs.Length > 0)
tableName = ((TableAttribute)tableAttrs[0]).Name;
// set the description for the table
string tableComment = reader.GetCommentsForResource(tableType, null, XmlResourceType.Type);
if (!string.IsNullOrEmpty(tableComment))
SetDescriptionForObject(tableName, null, tableComment);
// get all of the documentation for each property/column
ObjectDocumentation[] columnComments = reader.GetCommentsForResource(tableType);
foreach (var column in columnComments)
{
SetDescriptionForObject(tableName, column.PropertyName, column.Documentation);
}
}
private void SetDescriptionForObject(string tableName, string columnName, string description)
{
string strGetDesc = "";
// determine if there is already an extended description
if(string.IsNullOrEmpty(columnName))
strGetDesc = "select [value] from fn_listextendedproperty('MS_Description','schema','dbo','table',N'" + tableName + "',null,null);";
else
strGetDesc = "select [value] from fn_listextendedproperty('MS_Description','schema','dbo','table',N'" + tableName + "','column',null) where objname = N'" + columnName + "';";
var prevDesc = (string)RunSqlScalar(strGetDesc);
var parameters = new List<SqlParameter>
{
new SqlParameter("@table", tableName),
new SqlParameter("@desc", description)
};
// is it an update, or new?
string funcName = "sp_addextendedproperty";
if (!string.IsNullOrEmpty(prevDesc))
funcName = "sp_updateextendedproperty";
string query = @"EXEC " + funcName + @" @name = N'MS_Description', @value = @desc,@level0type = N'Schema', @level0name = 'dbo',@level1type = N'Table', @level1name = @table";
// if a column is specified, add a column description
if (!string.IsNullOrEmpty(columnName))
{
parameters.Add(new SqlParameter("@column", columnName));
query += ", @level2type = N'Column', @level2name = @column";
}
RunSql(query, parameters.ToArray());
}
DbCommand CreateCommand(string cmdText, params SqlParameter[] parameters)
{
var cmd = context.Database.Connection.CreateCommand();
cmd.CommandText = cmdText;
cmd.Transaction = transaction;
foreach (var p in parameters)
cmd.Parameters.Add(p);
return cmd;
}
void RunSql(string cmdText, params SqlParameter[] parameters)
{
var cmd = CreateCommand(cmdText, parameters);
cmd.ExecuteNonQuery();
}
object RunSqlScalar(string cmdText, params SqlParameter[] parameters)
{
var cmd = CreateCommand(cmdText, parameters);
return cmd.ExecuteScalar();
}
}
public static class ReflectionUtil
{
public static bool InheritsOrImplements(this Type child, Type parent)
{
parent = ResolveGenericTypeDefinition(parent);
var currentChild = child.IsGenericType
? child.GetGenericTypeDefinition()
: child;
while (currentChild != typeof(object))
{
if (parent == currentChild || HasAnyInterfaces(parent, currentChild))
return true;
currentChild = currentChild.BaseType != null
&& currentChild.BaseType.IsGenericType
? currentChild.BaseType.GetGenericTypeDefinition()
: currentChild.BaseType;
if (currentChild == null)
return false;
}
return false;
}
private static bool HasAnyInterfaces(Type parent, Type child)
{
return child.GetInterfaces()
.Any(childInterface =>
{
var currentInterface = childInterface.IsGenericType
? childInterface.GetGenericTypeDefinition()
: childInterface;
return currentInterface == parent;
});
}
private static Type ResolveGenericTypeDefinition(Type parent)
{
var shouldUseGenericType = true;
if (parent.IsGenericType && parent.GetGenericTypeDefinition() != parent)
shouldUseGenericType = false;
if (parent.IsGenericType && shouldUseGenericType)
parent = parent.GetGenericTypeDefinition();
return parent;
}
}
public static class ContextExtensions
{
public static string GetTableName(this DbContext context, Type tableType)
{
MethodInfo method = typeof(ContextExtensions).GetMethod("GetTableName", new Type[] { typeof(DbContext) })
.MakeGenericMethod(new Type[] { tableType });
return (string)method.Invoke(context, new object[] { context });
}
public static string GetTableName<T>(this DbContext context) where T : class
{
ObjectContext objectContext = ((IObjectContextAdapter)context).ObjectContext;
return objectContext.GetTableName<T>();
}
public static string GetTableName<T>(this ObjectContext context) where T : class
{
string sql = context.CreateObjectSet<T>().ToTraceString();
Regex regex = new Regex("FROM (?<table>.*) AS");
Match match = regex.Match(sql);
string table = match.Groups["table"].Value;
return table;
}
}
从visual studio获取注释标记的类生成了XML文档文件：
public class XmlAnnotationReader
{
public string XmlPath { get; protected internal set; }
public XmlDocument Document { get; protected internal set; }
public XmlAnnotationReader()
{
var assembly = Assembly.GetExecutingAssembly();
string resourceName = String.Format("{0}.App_Data.{0}.XML", assembly.GetName().Name);
this.XmlPath = resourceName;
using (Stream stream = assembly.GetManifestResourceStream(resourceName))
{
using (StreamReader reader = new StreamReader(stream))
{
XmlDocument doc = new XmlDocument();
//string result = reader.ReadToEnd();
doc.Load(reader);
this.Document = doc;
}
}
}
public XmlAnnotationReader(string xmlPath)
{
this.XmlPath = xmlPath;
if (File.Exists(xmlPath))
{
XmlDocument doc = new XmlDocument();
doc.Load(this.XmlPath);
this.Document = doc;
}
else
throw new FileNotFoundException(String.Format("Could not find the XmlDocument at the specified path: {0}\r\nCurrent Path: {1}", xmlPath, Assembly.GetExecutingAssembly().Location));
}
/// <summary>
/// Retrievethe XML comments documentation for a given resource
/// Eg. ITN.Data.Models.Entity.TestObject.MethodName
/// </summary>
/// <returns></returns>
public string GetCommentsForResource(string resourcePath, XmlResourceType type)
{
XmlNode node = Document.SelectSingleNode(String.Format("//member[starts-with(@name, '{0}:{1}')]/summary", GetObjectTypeChar(type), resourcePath));
if (node != null)
{
string xmlResult = node.InnerText;
string trimmedResult = Regex.Replace(xmlResult, @"\s+", " ");
return trimmedResult;
}
return string.Empty;
}
/// <summary>
/// Retrievethe XML comments documentation for a given resource
/// Eg. ITN.Data.Models.Entity.TestObject.MethodName
/// </summary>
/// <returns></returns>
public ObjectDocumentation[] GetCommentsForResource(Type objectType)
{
List<ObjectDocumentation> comments = new List<ObjectDocumentation>();
string resourcePath = objectType.FullName;
PropertyInfo[] properties = objectType.GetProperties();
FieldInfo[] fields = objectType.GetFields();
List<ObjectDocumentation> objectNames = new List<ObjectDocumentation>();
objectNames.AddRange(properties.Select(x => new ObjectDocumentation() { PropertyName = x.Name, Type = XmlResourceType.Property }).ToList());
objectNames.AddRange(properties.Select(x => new ObjectDocumentation() { PropertyName = x.Name, Type = XmlResourceType.Field }).ToList());
foreach (var property in objectNames)
{
XmlNode node = Document.SelectSingleNode(String.Format("//member[starts-with(@name, '{0}:{1}.{2}')]/summary", GetObjectTypeChar(property.Type), resourcePath, property.PropertyName ));
if (node != null)
{
string xmlResult = node.InnerText;
string trimmedResult = Regex.Replace(xmlResult, @"\s+", " ");
property.Documentation = trimmedResult;
comments.Add(property);
}
}
return comments.ToArray();
}
/// <summary>
/// Retrievethe XML comments documentation for a given resource
/// </summary>
/// <param name="objectType">The type of class to retrieve documenation on</param>
/// <param name="propertyName">The name of the property in the specified class</param>
/// <param name="resourceType"></param>
/// <returns></returns>
public string GetCommentsForResource(Type objectType, string propertyName, XmlResourceType resourceType)
{
List<ObjectDocumentation> comments = new List<ObjectDocumentation>();
string resourcePath = objectType.FullName;
string scopedElement = resourcePath;
if (propertyName != null && resourceType != XmlResourceType.Type)
scopedElement += "." + propertyName;
XmlNode node = Document.SelectSingleNode(String.Format("//member[starts-with(@name, '{0}:{1}')]/summary", GetObjectTypeChar(resourceType), scopedElement));
if (node != null)
{
string xmlResult = node.InnerText;
string trimmedResult = Regex.Replace(xmlResult, @"\s+", " ");
return trimmedResult;
}
return string.Empty;
}
private string GetObjectTypeChar(XmlResourceType type)
{
switch (type)
{
case XmlResourceType.Field:
return "F";
case XmlResourceType.Method:
return "M";
case XmlResourceType.Property:
return "P";
case XmlResourceType.Type:
return "T";
}
return string.Empty;
}
}
public class ObjectDocumentation
{
public string PropertyName { get; set; }
public string Documentation { get; set; }
public XmlResourceType Type { get; set; }
}
public enum XmlResourceType
{
Method,
Property,
Field,
Type
}
答案 2 :(得分：3)
你能不能使用ExceuteSqlCommand方法。在这里，您可以明确定义要在表中添加的任何元属性。
http://msdn.microsoft.com/en-us/library/system.data.entity.database.executesqlcommand(v=vs.103).aspx
答案 3 :(得分：3)
谢谢 Mr.Mahmoodvcs 以获得出色的解决方案。 允许我修改它只需替换＆＃34; DisplayAttribute＆＃34;使用＆＃34; DescriptionAttribute＆＃34; 注意使用：
[Display(Name="Description here")]
你将使用：
[Description("Description here")]
所以它也包括表格。
public class DbDescriptionUpdater<TContext>
where TContext : System.Data.Entity.DbContext
{
public DbDescriptionUpdater(TContext context)
{
this.context = context;
}
Type contextType;
TContext context;
DbTransaction transaction;
public void UpdateDatabaseDescriptions()
{
contextType = typeof(TContext);
this.context = context;
var props = contextType.GetProperties(System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.Public);
transaction = null;
try
{
context.Database.Connection.Open();
transaction = context.Database.Connection.BeginTransaction();
foreach (var prop in props)
{
if (prop.PropertyType.InheritsOrImplements((typeof(DbSet<>))))
{
var tableType = prop.PropertyType.GetGenericArguments()[0];
SetTableDescriptions(tableType);
}
}
transaction.Commit();
}
catch
{
if (transaction != null)
transaction.Rollback();
throw;
}
finally
{
if (context.Database.Connection.State == System.Data.ConnectionState.Open)
context.Database.Connection.Close();
}
}
private void SetTableDescriptions(Type tableType)
{
string fullTableName = context.GetTableName(tableType);
Regex regex = new Regex(@"(\[\w+\]\.)?\[(?<table>.*)\]");
Match match = regex.Match(fullTableName);
string tableName;
if (match.Success)
tableName = match.Groups["table"].Value;
else
tableName = fullTableName;
var tableAttrs = tableType.GetCustomAttributes(typeof(TableAttribute), false);
if (tableAttrs.Length > 0)
tableName = ((TableAttribute)tableAttrs[0]).Name;
var table_attrs = tableType.GetCustomAttributes(typeof(DescriptionAttribute), false);
if (table_attrs != null && table_attrs.Length > 0)
SetTableDescription(tableName, ((DescriptionAttribute)table_attrs[0]).Description);
foreach (var prop in tableType.GetProperties(System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance))
{
if (prop.PropertyType.IsClass && prop.PropertyType != typeof(string))
continue;
var attrs = prop.GetCustomAttributes(typeof(DescriptionAttribute), false);
if (attrs != null && attrs.Length > 0)
SetColumnDescription(tableName, prop.Name, ((DescriptionAttribute)attrs[0]).Description);
}
}
private void SetColumnDescription(string tableName, string columnName, string description)
{
string strGetDesc = "select [value] from fn_listextendedproperty('MS_Description','schema','dbo','table',N'" + tableName + "','column',null) where objname = N'" + columnName + "';";
var prevDesc = RunSqlScalar(strGetDesc);
if (prevDesc == null)
{
RunSql(@"EXEC sp_addextendedproperty
@name = N'MS_Description', @value = @desc,
@level0type = N'Schema', @level0name = 'dbo',
@level1type = N'Table', @level1name = @table,
@level2type = N'Column', @level2name = @column;",
new SqlParameter("@table", tableName),
new SqlParameter("@column", columnName),
new SqlParameter("@desc", description));
}
else
{
RunSql(@"EXEC sp_updateextendedproperty
@name = N'MS_Description', @value = @desc,
@level0type = N'Schema', @level0name = 'dbo',
@level1type = N'Table', @level1name = @table,
@level2type = N'Column', @level2name = @column;",
new SqlParameter("@table", tableName),
new SqlParameter("@column", columnName),
new SqlParameter("@desc", description));
}
}
private void SetTableDescription(string tableName, string description)
{
string strGetDesc = "select [value] from fn_listextendedproperty('MS_Description','schema','dbo','table',N'" + tableName + "',null,null);";
var prevDesc = RunSqlScalar(strGetDesc);
if (prevDesc == null)
{
RunSql(@"EXEC sp_addextendedproperty
@name = N'MS_Description', @value = @desc,
@level0type = N'Schema', @level0name = 'dbo',
@level1type = N'Table', @level1name = @table;",
new SqlParameter("@table", tableName),
new SqlParameter("@desc", description));
}
else
{
RunSql(@"EXEC sp_updateextendedproperty
@name = N'MS_Description', @value = @desc,
@level0type = N'Schema', @level0name = 'dbo',
@level1type = N'Table', @level1name = @table;",
new SqlParameter("@table", tableName),
new SqlParameter("@desc", description));
}
}
DbCommand CreateCommand(string cmdText, params SqlParameter[] parameters)
{
var cmd = context.Database.Connection.CreateCommand();
cmd.CommandText = cmdText;
cmd.Transaction = transaction;
foreach (var p in parameters)
cmd.Parameters.Add(p);
return cmd;
}
void RunSql(string cmdText, params SqlParameter[] parameters)
{
var cmd = CreateCommand(cmdText, parameters);
cmd.ExecuteNonQuery();
}
object RunSqlScalar(string cmdText, params SqlParameter[] parameters)
{
var cmd = CreateCommand(cmdText, parameters);
return cmd.ExecuteScalar();
}
}
public static class ReflectionUtil
{
public static bool InheritsOrImplements(this Type child, Type parent)
{
parent = ResolveGenericTypeDefinition(parent);
var currentChild = child.IsGenericType
? child.GetGenericTypeDefinition()
: child;
while (currentChild != typeof(object))
{
if (parent == currentChild || HasAnyInterfaces(parent, currentChild))
return true;
currentChild = currentChild.BaseType != null
&& currentChild.BaseType.IsGenericType
? currentChild.BaseType.GetGenericTypeDefinition()
: currentChild.BaseType;
if (currentChild == null)
return false;
}
return false;
}
private static bool HasAnyInterfaces(Type parent, Type child)
{
return child.GetInterfaces()
.Any(childInterface =>
{
var currentInterface = childInterface.IsGenericType
? childInterface.GetGenericTypeDefinition()
: childInterface;
return currentInterface == parent;
});
}
private static Type ResolveGenericTypeDefinition(Type parent)
{
var shouldUseGenericType = true;
if (parent.IsGenericType && parent.GetGenericTypeDefinition() != parent)
shouldUseGenericType = false;
if (parent.IsGenericType && shouldUseGenericType)
parent = parent.GetGenericTypeDefinition();
return parent;
}
}
public static class ContextExtensions
{
public static string GetTableName(this DbContext context, Type tableType)
{
MethodInfo method = typeof(ContextExtensions).GetMethod("GetTableName", new Type[] { typeof(DbContext) })
.MakeGenericMethod(new Type[] { tableType });
return (string)method.Invoke(context, new object[] { context });
}
public static string GetTableName<T>(this DbContext context) where T : class
{
ObjectContext objectContext = ((IObjectContextAdapter)context).ObjectContext;
return objectContext.GetTableName<T>();
}
public static string GetTableName<T>(this ObjectContext context) where T : class
{
string sql = context.CreateObjectSet<T>().ToTraceString();
Regex regex = new Regex("FROM (?<table>.*) AS");
Match match = regex.Match(sql);
string table = match.Groups["table"].Value;
return table;
}
}
答案 4 :(得分：0)
虽然问题与EF4有关，但此答案针对的是EF6，考虑到自提出问题以来经过的时间，EF6应该是合适的。
我认为评论属于Migration Up和Down方法，而不是某些Seed方法。
因此，按照@MichaelBrown的建议，首先要启用XML文档输出，并将文档文件作为嵌入式资源包含在您的项目中。
然后，使用Convention将注释转换为表/列注释。对于多行注释和摆脱过多的空白，需要进行一些调整。
public class CommentConvention : Convention
{
public const string NewLinePlaceholder = "<<NEWLINE>>";
public CommentConvention()
{
var docuXml = new XmlDocument();
// Read the documentation xml
using (var commentStream = Assembly.GetExecutingAssembly().GetManifestResourceStream("Namespace.Documentation.xml"))
{
docuXml.Load(commentStream);
}
// configure class/table comment
Types()
.Having(pi => docuXml.SelectSingleNode($"//member[starts-with(@name, 'T:{pi?.FullName}')]/summary"))
.Configure((c, a) =>
{
c.HasTableAnnotation("Comment", GetCommentTextWithNewlineReplacement(a));
});
// configure property/column comments
Properties()
.Having(pi =>
docuXml.SelectSingleNode(
$"//member[starts-with(@name, 'P:{pi?.DeclaringType?.FullName}.{pi?.Name}')]/summary"))
.Configure((c, a) => { c.HasColumnAnnotation("Comment", GetCommentTextWithNewlineReplacement(a)); });
}
// adjust the documentation text to handle newline and whitespace
private static string GetCommentTextWithNewlineReplacement(XmlNode a)
{
if (string.IsNullOrWhiteSpace(a.InnerText))
{
return null;
}
return string.Join(
NewLinePlaceholder,
a.InnerText.Trim()
.Split(new string[] {"\r\n", "\r", "\n"}, StringSplitOptions.None)
.Select(line => line.Trim()));
}
}
在OnModelCreating方法中注册约定。
预期结果： 创建新的迁移后，注释将作为注释（如
）包含在内CreateTable(
"schema.Table",
c => new
{
Id = c.Decimal(nullable: false, precision: 10, scale: 0, identity: true,
annotations: new Dictionary<string, AnnotationValues>
{
{
"Comment",
new AnnotationValues(oldValue: null, newValue: "Commenting the Id Column")
},
}),
// ...
继续第二部分：调整SQL生成器以根据注释创建注释。
这是针对Oracle的，但是MS Sql应该非常相似
class CustomOracleSqlCodeGen : MigrationSqlGenerator
{
// the actual SQL generator
private readonly MigrationSqlGenerator _innerSqlGenerator;
public CustomOracleSqlCodeGen(MigrationSqlGenerator innerSqlGenerator)
{
_innerSqlGenerator = innerSqlGenerator;
}
public override IEnumerable<MigrationStatement> Generate(IEnumerable<MigrationOperation> migrationOperations, string providerManifestToken)
{
var ms = _innerSqlGenerator.Generate(AddCommentSqlStatements(migrationOperations), providerManifestToken);
return ms;
}
// generate additional SQL operations to produce comments
IEnumerable<MigrationOperation> AddCommentSqlStatements(IEnumerable<MigrationOperation> migrationOperations)
{
foreach (var migrationOperation in migrationOperations)
{
// the original inputted operation
yield return migrationOperation;
// create additional operations to produce comments
if (migrationOperation is CreateTableOperation cto)
{
foreach (var ctoAnnotation in cto.Annotations.Where(x => x.Key == "Comment"))
{
if (ctoAnnotation.Value is string annotation)
{
var commentString = annotation.Replace(
CommentConvention.NewLinePlaceholder,
Environment.NewLine);
yield return new SqlOperation($"COMMENT ON TABLE {cto.Name} IS '{commentString}'");
}
}
foreach (var columnModel in cto.Columns)
{
foreach (var columnModelAnnotation in columnModel.Annotations.Where(x => x.Key == "Comment"))
{
if (columnModelAnnotation.Value is AnnotationValues annotation)
{
var commentString = (annotation.NewValue as string)?.Replace(
CommentConvention.NewLinePlaceholder,
Environment.NewLine);
yield return new SqlOperation(
$"COMMENT ON COLUMN {cto.Name}.{columnModel.Name} IS '{commentString}'");
}
}
}
}
}
}
}
在DbMigrationsConfiguration构造函数中，注册新的代码生成器（同样，这是oracle特定的，但与其他SQL提供程序类似）
internal sealed class Configuration : DbMigrationsConfiguration<EntityFramework.Dev.ZdbTestContext>
{
public Configuration()
{
AutomaticMigrationsEnabled = false;
var cg = GetSqlGenerator("Oracle.ManagedDataAccess.Client");
SetSqlGenerator("Oracle.ManagedDataAccess.Client", new CustomOracleSqlCodeGen(cg));
}
// ...
预期结果：将Up和Down方法中的注释注释转换为SQL语句，从而更改数据库中的注释。