public AssociationLink(IEntityComplexPropertyMetadata owner, string name, string role)
{
_owner = owner;
_name = name;
_role = role;
_principal = _foreign = null;
}
private bool IsLinked(IEntityComplexPropertyMetadata owner, IEntitySimplexPropertyMetadata property)
{
var links = owner.Links;
for (int i = 0; i < links.Length; i++)
{
if (object.Equals(links[i].Foreign, property))
{
return(true);
}
}
return(false);
}
private static IEntityPropertyMetadataCollection GetAssociatedProperties(IEntityComplexPropertyMetadata property, ref ICollection <IEntityMetadata> ancestors)
{
var index = property.Role.IndexOf(':');
var entityName = index < 0 ? property.Role : property.Role.Substring(0, index);
if (!property.Entity.Metadata.Manager.Entities.TryGet(entityName, out var entity))
{
throw new DataException($"The '{entityName}' target entity associated with the Role in the '{property.Entity.Name}:{property.Name}' complex property does not exist.");
}
if (index < 0)
{
return(entity.Properties);
}
var parts = property.Role.Substring(index + 1).Split('.');
var properties = entity.Properties;
foreach (var part in parts)
{
if (properties == null)
{
return(null);
}
if (!properties.TryGet(part, out var found))
{
found = FindBaseProperty(ref properties, part, ref ancestors);
if (found == null)
{
throw new DataException($"The '{part}' property of '{properties.Entity.Name}' entity does not existed.");
}
}
if (found.IsSimplex)
{
return(null);
}
properties = GetAssociatedProperties((IEntityComplexPropertyMetadata)found, ref ancestors);
}
return(properties);
}
/// <summary>
/// 获取指定导航属性约束项值的常量表达式。
/// </summary>
/// <param name="property">指定的导航属性。</param>
/// <param name="constraint">指定的导航属性的约束项。</param>
/// <returns>返回的约束项值对应关联属性数据类型的常量表达式。</returns>
public static ConstantExpression GetConstraintValue(this IEntityComplexPropertyMetadata property, AssociationConstraint constraint)
{
if (constraint.Value == null)
{
return(ConstantExpression.Null);
}
var entity = constraint.Actor == AssociationConstraintActor.Principal ? property.Entity : property.Foreign;
//获取指定导航属性的关联属性
if (!entity.Properties.TryGet(constraint.Name, out var associatedProperty))
{
throw new DataException($"The specified '{constraint.Name}' constraint does not exist in the '{property.Entity.Name}.{property.Name}' navigation property.");
}
//返回约束项值转换成关联属性数据类型的常量表达式
return(Expression.Constant(Zongsoft.Common.Convert.ConvertValue(constraint.Value, Utility.FromDbType(associatedProperty.Type))));
}
