How to ignore mapping of property using mapping by

问题:

Is there any way to avoid a property from being mapped with NHibernate 3.2 using mapping by code conventions? By default, all properties are mapped.

回答1:

There are two options as far as I know:

1)Extend ConventionModelMapper and SimpleModelInspector to extend IsPersistentProperty such that it meets your need.

2)Use IsPersistentProperty as follows:

...
mapper.IsPersistentProperty((memberInfo, declared) => IsPersistentProperty(mapper.ModelInspector, memberInfo, declared, "YourPropertyName"));
...


public static bool IsPersistentProperty(IModelInspector modelInspector, MemberInfo member, bool declared, string propertyName)
{
    return (declared ||(member is PropertyInfo) && !IsReadOnlyProperty(member)) && !member.Name.Equals(propertyName);
}

private static bool IsReadOnlyProperty(MemberInfo subject)
{
    const BindingFlags defaultBinding = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.DeclaredOnly;

    var property = subject as PropertyInfo;
    if (property == null)
    {
        return false;
    }
    if (CanReadCantWriteInsideType(property) || CanReadCantWriteInBaseType(property))
    {
        return !PropertyToField.DefaultStrategies.Values.Any(s => subject.DeclaringType.GetField(s.GetFieldName(property.Name), defaultBinding) != null) || IsAutoproperty(property);
    }
    return false;
}

private static bool IsAutoproperty(PropertyInfo property)
{
    return property.ReflectedType.GetFields(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance
                                                                             | BindingFlags.DeclaredOnly).Any(pi => pi.Name == string.Concat("<", property.Name, ">k__BackingField"));
}

private static bool CanReadCantWriteInsideType(PropertyInfo property)
{
    return !property.CanWrite && property.CanRead && property.DeclaringType == property.ReflectedType;
}

private static bool CanReadCantWriteInBaseType(PropertyInfo property)
{
    if (property.DeclaringType == property.ReflectedType)
    {
        return false;
    }
    var rfprop = property.DeclaringType.GetProperties(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance
                                                                             | BindingFlags.DeclaredOnly).SingleOrDefault(pi => pi.Name == property.Name);
    return rfprop != null && !rfprop.CanWrite && rfprop.CanRead;
}

回答2:

2) As alternative to copy&paste of default implementation of IsPersistentProperty it can be reused via reflection:

var mapper = new ConventionModelMapper();
var field = mapper.ModelInspector.GetType()
    .GetField( "isPersistentProperty", BindingFlags.NonPublic | BindingFlags.Instance );

var ispp = (Func<MemberInfo, bool, bool>)field.GetValue( mapper.ModelInspector );
mapper.IsPersistentProperty( ( mi, b ) => ispp( mi, b ) 
   && ( /*any conditions here*/ mi.Name != "SomeFiledName" ) );

Conditions can be moved to separate method or class. An stronly-typed wrapper based on expressions can be done above it.

回答3:

Duplicate: Ignore column using mapping by code in HNibernate

you can use the following:

mapper.IsPersistentProperty((mi, declared) =>
                                             {
                                                 if (mi.DeclaringType == typeof (YourType) && mi.Name == "PropertyNameToIgnore")
                                                     return false;
                                                 return true;
                                             });