public DataAssociationLink(IDataEntityComplexProperty owner, string name, string role)
{
_owner = owner;
_name = name;
_role = role;
_principal = _foreign = null;
}
public DataAssociationLink(IDataEntityComplexProperty owner, string foreign, string anchor = null)
{
if (string.IsNullOrEmpty(foreign))
{
throw new ArgumentNullException(nameof(foreign));
}
_owner = owner ?? throw new ArgumentNullException(nameof(owner));
_foreign = foreign;
_anchor = string.IsNullOrEmpty(anchor) ? foreign : anchor;
_foreignKey = null;
}
private static IDataEntityPropertyCollection GetAssociatedProperties(IDataEntityComplexProperty property, ref ICollection <IDataEntity> 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((IDataEntityComplexProperty)found, ref ancestors);
}
return(properties);
}
/// <inheritdoc />
public JoinClause Join(Aliaser aliaser, ISource source, IDataEntityComplexProperty complex, string fullPath = null)
{
var joins = JoinClause.Create(source,
complex,
fullPath,
name => this.From.TryGet(name, out var join) ? (JoinClause)join : null,
entity => new TableIdentifier(entity, aliaser.Generate()));
JoinClause last = null;
foreach (var join in joins)
{
if (!this.From.Contains(join))
{
this.From.Add(join);
}
last = join;
}
//返回最后一个Join子句
return(last);
}
/// <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 IDataEntityComplexProperty property, DataAssociationConstraint constraint)
{
if (constraint.Value == null)
{
return(ConstantExpression.Null);
}
var entity = constraint.Actor == DataAssociationConstraintActor.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 constraintProperty))
{
throw new DataException($"The specified '{constraint.Name}' constraint does not exist in the '{property.Entity.Name}.{property.Name}' navigation property.");
}
//如果约束项的关联属性不是简单属性则抛出异常
if (!constraintProperty.IsSimplex)
{
throw new DataException($"The specified '{constraint.Name}' constraint association property is not a simplex 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(((IDataEntitySimplexProperty)constraintProperty).Type))));
}
/// <summary>
/// 获取指定导航属性是否有约束定义。
/// </summary>
/// <param name="property">指定的导航属性。</param>
/// <returns>如果指定的导航属性定义了约束则返回真(True)，否则返回假(False)。</returns>
public static bool HasConstraints(this IDataEntityComplexProperty property)
{
return(property != null && property.Constraints != null && property.Constraints.Length > 0);
}
