protected override MemberAssignment VisitMemberAssignment(MemberAssignment node)
{
directlyInSelectMethod = false;
var rightSide = node.Expression as MemberExpression;
if (rightSide is null && node.Expression != null && node.Expression.NodeType == ExpressionType.Convert)
{
rightSide = ((UnaryExpression)node.Expression).Operand as MemberExpression;
}
var property = rightSide?.Member as PropertyInfo;
if (property != null)
{
PropertyLocalizationMapping mapping = GetLocalizationMapping(property);
if (mapping != null)
{
var localizationExpresison = GetLocalizationExpression(rightSide, mapping, _culture);
if (localizationExpresison != null)
{
node = Expression.Bind(node.Member, localizationExpresison);
}
}
return(base.VisitMemberAssignment(node));
}
return(base.VisitMemberAssignment(node));
}
protected override Expression VisitNew(NewExpression node)
{
directlyInSelectMethod = false;
return(Expression.New(node.Constructor, node.Arguments.Select(arg =>
{
var rightSide = arg as MemberExpression;
var property = rightSide?.Member as PropertyInfo;
if (property != null)
{
PropertyLocalizationMapping mapping = GetLocalizationMapping(property);
if (mapping != null)
{
var localizationExpresison = GetLocalizationExpression(rightSide, mapping, _culture);
if (localizationExpresison != null)
{
return localizationExpresison;
}
}
}
return Visit(arg);
})));
}
private PropertyLocalizationMapping GetLocalizationMapping(PropertyInfo sourceProperty)
{
if (sourceProperty is null)
{
return(null);
}
else if (sourceProperty.PropertyType != typeof(string))
{
return(null);
}
var replaceNodeAttribute = sourceProperty
.GetCustomAttributes(typeof(LocalizedQueryPlaceHolderAttribute), false)
.Cast <LocalizedQueryPlaceHolderAttribute>()
.FirstOrDefault();
if (replaceNodeAttribute is null)
{
return(null);
}
return(PropertyLocalizationMappings.GetOrAdd(sourceProperty, _ =>
{
if (sourceProperty.ReflectedType is null || sourceProperty.ReflectedType != typeof(LocalizedValueObject))
{
return null;
}
var mapping = new PropertyLocalizationMapping
{
ValueObjectType = sourceProperty.ReflectedType,
};
mapping.SerializedPropertyInfo = mapping.ValueObjectType.GetProperties().FirstOrDefault(p =>
p.PropertyType == typeof(string) && p.Name == nameof(LocalizedValueObject.Serialized));
if (mapping.SerializedPropertyInfo is null)
{
return null;
}
return mapping;
}));
protected override Expression VisitMember(MemberExpression node)
{
var property = node.Member as PropertyInfo;
if (directlyInSelectMethod)
{
PropertyLocalizationMapping mapping = GetLocalizationMapping(property);
if (mapping != null)
{
var localizationExpresison = GetLocalizationExpression(node, mapping, _culture, property.PropertyType);
if (localizationExpresison != null)
{
return(localizationExpresison);
}
}
return(base.VisitMember(node));
}
return(base.VisitMember(node));
}
private static Expression GetLocalizationExpression(MemberExpression memberExpression, PropertyLocalizationMapping mapping,
string culture, Type customReturnType = null)
{
// this method transforms member expression { e.Property.Localized }
// to { EntityFrameworkJsonExtensions.Value(e.Property.Serialized, "$.culture") ?? EntityFrameworkJsonExtensions.Value(e.Property.Serialized, "$.default") }
var baseLocalizationProperty = memberExpression.Expression; // {e.Property}
var serializedLocalizationProperty = Expression.Property(baseLocalizationProperty, mapping.SerializedPropertyInfo); // {e.Property.Serialized}
var localizedExpression = Expression.Call(typeof(EntityFrameworkJsonExtensions), nameof(EntityFrameworkJsonExtensions.Value)
, null, serializedLocalizationProperty, Expression.Constant($"$.{culture}"));
var defaultExpression = Expression.Call(typeof(EntityFrameworkJsonExtensions), nameof(EntityFrameworkJsonExtensions.Value)
, null, serializedLocalizationProperty, Expression.Constant($"$.{LocalizedValueObject.DefaultKey}"));
var localizedOrDefaultExpression = Expression.Coalesce(
localizedExpression,
defaultExpression);
var result = (customReturnType != null)
? Expression.Convert(localizedOrDefaultExpression, customReturnType) as Expression
: localizedOrDefaultExpression;
return(result);
}
