【发布时间】：2012-06-08 10:12:56
【问题描述】：
在 Dapper (http://code.google.com/p/dapper-dot-net/) 中，有没有办法忽略模型类中的属性，即在使用 Insert 扩展方法时？
我的模型类有一组 computed 属性，这些属性没有保存在关联的表中。
【问题讨论】：
标签： dapper
【发布时间】：2012-06-08 10:12:56
【问题描述】：
只需将[Computed] 属性添加到相关属性即可。
【讨论】：
如果您使用的是 Dapper.Contrib，请在 SqlMapperExtensions 中查看此代码：
private static List<PropertyInfo> ComputedPropertiesCache(Type type)
{
//...
var computedProperties = TypePropertiesCache(type).Where(p => p.GetCustomAttributes(true).Any(a => a is ComputedAttribute)).ToList();
var computedProperties = ComputedPropertiesCache(type);
var allPropertiesExceptKeyAndComputed = allProperties.Except(keyProperties.Union(computedProperties)).ToList();
//...
for (var i = 0; i < allPropertiesExceptKeyAndComputed.Count; i++)
{
//...
因此，如果您在类的属性中添加ComputedAttribute，Dapper.Contrib 将不会尝试将它们插入数据库！您不必担心让 Dapper 忽略这些属性，只需 Dapper.Contrib。因为如果您在 dapper 查询中使用 select * from tablename，它只会尝试映射存在的列。因此，您只需不要为标记为 [Computed] 的属性创建列。
【讨论】：
好吧，Dapper 没有Insert 扩展方法，即在 dapper.contrib、dapper 扩展或 dapper rainbow 中。
Dapper 本身允许你这样做：
Animal a = new Animal {Age = 10, Family = "Canine"}
// only insert Age
cnn.Execute("insert Animal(Age) values (@Age)", a);
要解决您有时可以做的一些扩展类：
cnn.InsertExtension("Animal", new{a.Age});
无论如何，对于复杂的过滤插入，您始终可以使用原始 Dapper。
【讨论】：
-
1) 是的，我指的是
Insert扩展方法，存在于Dapper.Contrib.Extensions的SqlMapperExtensions类中。对不起我的模棱两可。 2) 我在哪里可以找到您提到的InsertExtension？ -
这个答案没有回答 OP 关于“如何忽略属性？”的问题
如果您只是想从插入/更新语句中“隐藏”一个属性，那么在 dapper 扩展中有一种官方方法可以做到这一点：
using DapperExtensions.Mapper;
public class UserMapper : ClassMapper<User>
{
public UserMapper()
{
base.Map(m => m.IsTrialUser).Ignore();
base.AutoMap();
}
}
【讨论】：
我编写了 SqlMapperExtensions 类的修改版本，并添加了一个 string[] 参数 ExcludeProperties 用于排除列。使用此类，您可以进行如下调用：
// Insert
result = (int)cn.Insert<Animal>(box, new string[] { "Errors", "IsValid" });
// Update
cn.UpdateEntity<Animal>(box, new string[] { "Errors", "IsValid" });
在上面的语句中，我添加的 'Errors' 和 'IsValid' 属性不会包含在 SQL 语句中。
这是修改后的扩展类：
SqlMapperExtensions.cs
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Data;
using System.Diagnostics;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Collections.Concurrent;
using System.Reflection.Emit;
using System.Threading;
using System.Runtime.CompilerServices;
namespace Dapper.Contrib.Extensions
{
public static class SqlMapperExtensions
{
public interface IProxy
{
bool IsDirty { get; set; }
}
private static readonly ConcurrentDictionary<RuntimeTypeHandle, IEnumerable<PropertyInfo>> KeyProperties = new ConcurrentDictionary<RuntimeTypeHandle, IEnumerable<PropertyInfo>>();
private static readonly ConcurrentDictionary<RuntimeTypeHandle, IEnumerable<PropertyInfo>> TypeProperties = new ConcurrentDictionary<RuntimeTypeHandle, IEnumerable<PropertyInfo>>();
private static readonly ConcurrentDictionary<RuntimeTypeHandle, string> GetQueries = new ConcurrentDictionary<RuntimeTypeHandle, string>();
private static readonly ConcurrentDictionary<RuntimeTypeHandle, string> TypeTableName = new ConcurrentDictionary<RuntimeTypeHandle, string>();
private static IEnumerable<PropertyInfo> KeyPropertiesCache(Type type)
{
if (KeyProperties.ContainsKey(type.TypeHandle))
{
return KeyProperties[type.TypeHandle];
}
var allProperties = TypePropertiesCache(type);
var keyProperties = allProperties.Where(p => p.GetCustomAttributes(true).Any(a => a is KeyAttribute)).ToList();
if (keyProperties.Count == 0)
{
var idProp = allProperties.Where(p => p.Name.ToLower() == "id" || p.Name.ToLower() == (type.Name.ToLower() + "id")).FirstOrDefault();
if (idProp != null)
{
keyProperties.Add(idProp);
}
}
KeyProperties[type.TypeHandle] = keyProperties;
return keyProperties;
}
private static IEnumerable<PropertyInfo> TypePropertiesCache(Type type)
{
if (TypeProperties.ContainsKey(type.TypeHandle))
{
return TypeProperties[type.TypeHandle];
}
var properties = type.GetProperties();
TypeProperties[type.TypeHandle] = properties;
return properties;
}
/// <summary>
/// Returns a single entity by a single id from table "Ts". T must be of interface type.
/// Id must be marked with [Key] attribute.
/// Created entity is tracked/intercepted for changes and used by the Update() extension.
/// </summary>
/// <typeparam name="T">Interface type to create and populate</typeparam>
/// <param name="connection">Open SqlConnection</param>
/// <param name="id">Id of the entity to get, must be marked with [Key] attribute</param>
/// <returns>Entity of T</returns>
public static T GetEntity<T>(this IDbConnection connection, dynamic id, IDbTransaction transaction = null, int? commandTimeout = null) where T : class
{
var type = typeof(T);
string sql;
if (!GetQueries.TryGetValue(type.TypeHandle, out sql))
{
var keys = KeyPropertiesCache(type);
if (keys.Count() > 1)
throw new DataException("Get<T> only supports an entity with a single [Key] property");
if (keys.Count() == 0)
throw new DataException("Get<T> only supports en entity with a [Key] property");
var onlyKey = keys.First();
var name = GetTableName(type);
// TODO: pluralizer
// TODO: query information schema and only select fields that are both in information schema and underlying class / interface
sql = "select * from " + name + " where " + onlyKey.Name + " = @id";
GetQueries[type.TypeHandle] = sql;
}
var dynParms = new DynamicParameters();
dynParms.Add("@id", id);
T obj = null;
if (type.IsInterface)
{
var res = connection.Query(sql, dynParms).FirstOrDefault() as IDictionary<string, object>;
if (res == null)
return (T)((object)null);
obj = ProxyGenerator.GetInterfaceProxy<T>();
foreach (var property in TypePropertiesCache(type))
{
var val = res[property.Name];
property.SetValue(obj, val, null);
}
((IProxy)obj).IsDirty = false; //reset change tracking and return
}
else
{
obj = connection.Query<T>(sql, dynParms, transaction: transaction, commandTimeout: commandTimeout).FirstOrDefault();
}
return obj;
}
private static string GetTableName(Type type)
{
string name;
if (!TypeTableName.TryGetValue(type.TypeHandle, out name))
{
//name = type.Name + "s";
name = type.Name;
if (type.IsInterface && name.StartsWith("I"))
name = name.Substring(1);
//NOTE: This as dynamic trick should be able to handle both our own Table-attribute as well as the one in EntityFramework
var tableattr = type.GetCustomAttributes(false).Where(attr => attr.GetType().Name == "TableAttribute").SingleOrDefault() as
dynamic;
if (tableattr != null)
name = tableattr.Name;
TypeTableName[type.TypeHandle] = name;
}
return name;
}
/// <summary>
/// Inserts an entity into table "Ts" and returns identity id.
/// </summary>
/// <param name="connection">Open SqlConnection</param>
/// <param name="entityToInsert">Entity to insert</param>
/// <returns>Identity of inserted entity</returns>
public static long Insert<T>(this IDbConnection connection, T entityToInsert, string[] ExcludeProperties = null, IDbTransaction transaction = null, int? commandTimeout = null) where T : class
{
//using (var tx = connection.BeginTransaction())
//{
var type = typeof(T);
var name = GetTableName(type);
var sb = new StringBuilder(null);
sb.AppendFormat("insert into {0} (", name);
var allProperties = TypePropertiesCache(type);
if (ExcludeProperties != null)
{
List<PropertyInfo> someProperties = allProperties.ToList();
foreach (PropertyInfo prop in allProperties.ToArray())
{
if (ExcludeProperties.Contains(prop.Name))
{
someProperties.Remove(prop);
}
}
allProperties = someProperties.AsEnumerable();
}
var keyProperties = KeyPropertiesCache(type);
for (var i = 0; i < allProperties.Count(); i++)
{
var property = allProperties.ElementAt(i);
if (keyProperties.Contains(property)) continue;
sb.Append(property.Name);
if (i < allProperties.Count() - 1)
sb.Append(", ");
}
sb.Append(") values (");
for (var i = 0; i < allProperties.Count(); i++)
{
var property = allProperties.ElementAt(i);
if (keyProperties.Contains(property)) continue;
sb.AppendFormat("@{0}", property.Name);
if (i < allProperties.Count() - 1)
sb.Append(", ");
}
sb.Append(") ");
connection.Execute(sb.ToString(), entityToInsert, transaction: transaction, commandTimeout: commandTimeout);
//NOTE: would prefer to use IDENT_CURRENT('tablename') or IDENT_SCOPE but these are not available on SQLCE
var r = connection.Query("select @@IDENTITY id");
//tx.Commit();
return (int)r.First().id;
//}
}
/// <summary>
/// Updates entity in table "Ts", checks if the entity is modified if the entity is tracked by the Get() extension.
/// </summary>
/// <typeparam name="T">Type to be updated</typeparam>
/// <param name="connection">Open SqlConnection</param>
/// <param name="entityToUpdate">Entity to be updated</param>
/// <returns>true if updated, false if not found or not modified (tracked entities)</returns>
public static bool UpdateEntity<T>(this IDbConnection connection, T entityToUpdate, string[] ExcludeProperties = null, IDbTransaction transaction = null, int? commandTimeout = null) where T : class
{
var proxy = entityToUpdate as IProxy;
if (proxy != null)
{
if (!proxy.IsDirty) return false;
}
var type = typeof(T);
var keyProperties = KeyPropertiesCache(type);
if (keyProperties.Count() == 0)
throw new ArgumentException("Entity must have at least one [Key] property");
var name = GetTableName(type);
var sb = new StringBuilder();
sb.AppendFormat("update {0} set ", name);
var allProperties = TypePropertiesCache(type);
if (ExcludeProperties != null)
{
List<PropertyInfo> someProperties = allProperties.ToList();
foreach (PropertyInfo prop in allProperties.ToArray())
{
if (ExcludeProperties.Contains(prop.Name))
{
someProperties.Remove(prop);
}
}
allProperties = someProperties.AsEnumerable();
}
var nonIdProps = allProperties.Where(a => !keyProperties.Contains(a));
for (var i = 0; i < nonIdProps.Count(); i++)
{
var property = nonIdProps.ElementAt(i);
sb.AppendFormat("{0} = @{1}", property.Name, property.Name);
if (i < nonIdProps.Count() - 1)
sb.AppendFormat(", ");
}
sb.Append(" where ");
for (var i = 0; i < keyProperties.Count(); i++)
{
var property = keyProperties.ElementAt(i);
sb.AppendFormat("{0} = @{1}", property.Name, property.Name);
if (i < keyProperties.Count() - 1)
sb.AppendFormat(" and ");
}
var updated = connection.Execute(sb.ToString(), entityToUpdate, commandTimeout: commandTimeout, transaction: transaction);
return updated > 0;
}
/// <summary>
/// Delete entity in table "Ts".
/// </summary>
/// <typeparam name="T">Type of entity</typeparam>
/// <param name="connection">Open SqlConnection</param>
/// <param name="entityToDelete">Entity to delete</param>
/// <returns>true if deleted, false if not found</returns>
public static bool Delete<T>(this IDbConnection connection, T entityToDelete, IDbTransaction transaction = null, int? commandTimeout = null) where T : class
{
var type = typeof(T);
var keyProperties = KeyPropertiesCache(type);
if (keyProperties.Count() == 0)
throw new ArgumentException("Entity must have at least one [Key] property");
var name = GetTableName(type);
var sb = new StringBuilder();
sb.AppendFormat("delete from {0} where ", name);
for (var i = 0; i < keyProperties.Count(); i++)
{
var property = keyProperties.ElementAt(i);
sb.AppendFormat("{0} = @{1}", property.Name, property.Name);
if (i < keyProperties.Count() - 1)
sb.AppendFormat(" and ");
}
var deleted = connection.Execute(sb.ToString(), entityToDelete, transaction: transaction, commandTimeout: commandTimeout);
return deleted > 0;
}
class ProxyGenerator
{
private static readonly Dictionary<Type, object> TypeCache = new Dictionary<Type, object>();
private static AssemblyBuilder GetAsmBuilder(string name)
{
var assemblyBuilder = Thread.GetDomain().DefineDynamicAssembly(new AssemblyName { Name = name },
AssemblyBuilderAccess.Run); //NOTE: to save, use RunAndSave
return assemblyBuilder;
}
public static T GetClassProxy<T>()
{
// A class proxy could be implemented if all properties are virtual
// otherwise there is a pretty dangerous case where internal actions will not update dirty tracking
throw new NotImplementedException();
}
public static T GetInterfaceProxy<T>()
{
Type typeOfT = typeof(T);
if (TypeCache.ContainsKey(typeOfT))
{
return (T)TypeCache[typeOfT];
}
var assemblyBuilder = GetAsmBuilder(typeOfT.Name);
var moduleBuilder = assemblyBuilder.DefineDynamicModule("SqlMapperExtensions." + typeOfT.Name); //NOTE: to save, add "asdasd.dll" parameter
var interfaceType = typeof(Dapper.Contrib.Extensions.SqlMapperExtensions.IProxy);
var typeBuilder = moduleBuilder.DefineType(typeOfT.Name + "_" + Guid.NewGuid(),
TypeAttributes.Public | TypeAttributes.Class);
typeBuilder.AddInterfaceImplementation(typeOfT);
typeBuilder.AddInterfaceImplementation(interfaceType);
//create our _isDirty field, which implements IProxy
var setIsDirtyMethod = CreateIsDirtyProperty(typeBuilder);
// Generate a field for each property, which implements the T
foreach (var property in typeof(T).GetProperties())
{
var isId = property.GetCustomAttributes(true).Any(a => a is KeyAttribute);
CreateProperty<T>(typeBuilder, property.Name, property.PropertyType, setIsDirtyMethod, isId);
}
var generatedType = typeBuilder.CreateType();
//assemblyBuilder.Save(name + ".dll"); //NOTE: to save, uncomment
var generatedObject = Activator.CreateInstance(generatedType);
TypeCache.Add(typeOfT, generatedObject);
return (T)generatedObject;
}
private static MethodInfo CreateIsDirtyProperty(TypeBuilder typeBuilder)
{
var propType = typeof(bool);
var field = typeBuilder.DefineField("_" + "IsDirty", propType, FieldAttributes.Private);
var property = typeBuilder.DefineProperty("IsDirty",
System.Reflection.PropertyAttributes.None,
propType,
new Type[] { propType });
const MethodAttributes getSetAttr = MethodAttributes.Public | MethodAttributes.NewSlot | MethodAttributes.SpecialName |
MethodAttributes.Final | MethodAttributes.Virtual | MethodAttributes.HideBySig;
// Define the "get" and "set" accessor methods
var currGetPropMthdBldr = typeBuilder.DefineMethod("get_" + "IsDirty",
getSetAttr,
propType,
Type.EmptyTypes);
var currGetIL = currGetPropMthdBldr.GetILGenerator();
currGetIL.Emit(OpCodes.Ldarg_0);
currGetIL.Emit(OpCodes.Ldfld, field);
currGetIL.Emit(OpCodes.Ret);
var currSetPropMthdBldr = typeBuilder.DefineMethod("set_" + "IsDirty",
getSetAttr,
null,
new Type[] { propType });
var currSetIL = currSetPropMthdBldr.GetILGenerator();
currSetIL.Emit(OpCodes.Ldarg_0);
currSetIL.Emit(OpCodes.Ldarg_1);
currSetIL.Emit(OpCodes.Stfld, field);
currSetIL.Emit(OpCodes.Ret);
property.SetGetMethod(currGetPropMthdBldr);
property.SetSetMethod(currSetPropMthdBldr);
var getMethod = typeof(Dapper.Contrib.Extensions.SqlMapperExtensions.IProxy).GetMethod("get_" + "IsDirty");
var setMethod = typeof(Dapper.Contrib.Extensions.SqlMapperExtensions.IProxy).GetMethod("set_" + "IsDirty");
typeBuilder.DefineMethodOverride(currGetPropMthdBldr, getMethod);
typeBuilder.DefineMethodOverride(currSetPropMthdBldr, setMethod);
return currSetPropMthdBldr;
}
private static void CreateProperty<T>(TypeBuilder typeBuilder, string propertyName, Type propType, MethodInfo setIsDirtyMethod, bool isIdentity)
{
//Define the field and the property
var field = typeBuilder.DefineField("_" + propertyName, propType, FieldAttributes.Private);
var property = typeBuilder.DefineProperty(propertyName,
System.Reflection.PropertyAttributes.None,
propType,
new Type[] { propType });
const MethodAttributes getSetAttr = MethodAttributes.Public | MethodAttributes.Virtual |
MethodAttributes.HideBySig;
// Define the "get" and "set" accessor methods
var currGetPropMthdBldr = typeBuilder.DefineMethod("get_" + propertyName,
getSetAttr,
propType,
Type.EmptyTypes);
var currGetIL = currGetPropMthdBldr.GetILGenerator();
currGetIL.Emit(OpCodes.Ldarg_0);
currGetIL.Emit(OpCodes.Ldfld, field);
currGetIL.Emit(OpCodes.Ret);
var currSetPropMthdBldr = typeBuilder.DefineMethod("set_" + propertyName,
getSetAttr,
null,
new Type[] { propType });
//store value in private field and set the isdirty flag
var currSetIL = currSetPropMthdBldr.GetILGenerator();
currSetIL.Emit(OpCodes.Ldarg_0);
currSetIL.Emit(OpCodes.Ldarg_1);
currSetIL.Emit(OpCodes.Stfld, field);
currSetIL.Emit(OpCodes.Ldarg_0);
currSetIL.Emit(OpCodes.Ldc_I4_1);
currSetIL.Emit(OpCodes.Call, setIsDirtyMethod);
currSetIL.Emit(OpCodes.Ret);
//TODO: Should copy all attributes defined by the interface?
if (isIdentity)
{
var keyAttribute = typeof(KeyAttribute);
var myConstructorInfo = keyAttribute.GetConstructor(new Type[] { });
var attributeBuilder = new CustomAttributeBuilder(myConstructorInfo, new object[] { });
property.SetCustomAttribute(attributeBuilder);
}
property.SetGetMethod(currGetPropMthdBldr);
property.SetSetMethod(currSetPropMthdBldr);
var getMethod = typeof(T).GetMethod("get_" + propertyName);
var setMethod = typeof(T).GetMethod("set_" + propertyName);
typeBuilder.DefineMethodOverride(currGetPropMthdBldr, getMethod);
typeBuilder.DefineMethodOverride(currSetPropMthdBldr, setMethod);
}
}
}
[AttributeUsage(AttributeTargets.Class)]
public class TableAttribute : Attribute
{
public TableAttribute(string tableName)
{
Name = tableName;
}
public string Name { get; private set; }
}
}
【讨论】：
我编写了一个轻量级 ORM，它是 Dapper 的扩展。它实际上可以满足您的需求。如果你去掉属性的“成员”属性，ORM 会将它从插入中排除。
【讨论】：