Ignoring properties in Dapper - dapper

Question

In Dapper (http://code.google.com/p/dapper-dot-net/), is there a way to ignore properties in the model class, namely when using the Insert extension method?
My model class has a set of computed properties which are not persisted in the associated table.

Answer 1

Well, Dapper has no Insert extension method, that is in dapper.contrib, dapper extensions or dapper rainbow.
Dapper itself allows you to do:
Animal a = new Animal {Age = 10, Family = "Canine"}
// only insert Age
cnn.Execute("insert Animal(Age) values (#Age)", a);
To work around for some of the extension classes you can sometimes do:
cnn.InsertExtension("Animal", new{a.Age});
Regardless, you can always fall back to raw Dapper for your complex filtered inserts.

Answer 2

If you are using Dapper.Contrib, check out this code in SqlMapperExtensions:
https://github.com/StackExchange/dapper-dot-net/blob/master/Dapper.Contrib/SqlMapperExtensions.cs#L54-L66
private static List<PropertyInfo> ComputedPropertiesCache(Type type)
{
//...
var computedProperties = TypePropertiesCache(type).Where(p => p.GetCustomAttributes(true).Any(a => a is ComputedAttribute)).ToList();
and https://github.com/StackExchange/dapper-dot-net/blob/master/Dapper.Contrib/SqlMapperExtensions.Async.cs#L147-L165
var computedProperties = ComputedPropertiesCache(type);
var allPropertiesExceptKeyAndComputed = allProperties.Except(keyProperties.Union(computedProperties)).ToList();
//...
for (var i = 0; i < allPropertiesExceptKeyAndComputed.Count; i++)
{
//...
So if you add a ComputedAttribute to your properties on your class, Dapper.Contrib won't try to insert them in to the database! You shouldn't have to worry about getting Dapper to ignore those properties, only Dapper.Contrib. Because if you use select * from tablename in your dapper queries,it will only try to map columns that exist. So you just don't create columns for the properties which you marked as [Computed].

Answer 3

Just add the [Computed] attribute to the properties in question.

Answer 4

If you just want to "hide" a property from your Insert/Update statements then there is one official way to do this in dapper extensions:
using DapperExtensions.Mapper;
public class UserMapper : ClassMapper<User>
{
public UserMapper()
{
base.Map(m => m.IsTrialUser).Ignore();
base.AutoMap();
}
}

Answer 5

I wrote a modified version of the SqlMapperExtensions class and added a string[] parameter ExcludeProperties for excluding columns. Using this class you can make calls like:
// Insert
result = (int)cn.Insert<Animal>(box, new string[] { "Errors", "IsValid" });
// Update
cn.UpdateEntity<Animal>(box, new string[] { "Errors", "IsValid" });
In the statements above, the 'Errors' and 'IsValid' properties I added for will not be included in the SQL statements.
Here's the modified extensions class:
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; }
}
}

Answer 6

I wrote a lightweight ORM that's an extension of Dapper. It actually does what you need. If you leave off the "Member" attribute of the property, the ORM will exclude it from the Insert.
You can access it at https://www.github.com/ricericebaby/ADOCRUD