public static ISource From(this IStatement statement, TableIdentifier origin, string memberPath, Func <ISource, IDataEntityComplexProperty, ISource> subqueryFactory, out IDataEntityProperty property)
{
var found = origin.Reduce(memberPath, ctx =>
{
var source = ctx.Source;
if (ctx.Ancestors != null)
{
foreach (var ancestor in ctx.Ancestors)
{
source = statement.Join(source, ancestor, ctx.Path);
}
}
if (ctx.Property.IsComplex)
{
var complex = (IDataEntityComplexProperty)ctx.Property;
if (complex.Multiplicity == DataAssociationMultiplicity.Many)
{
if (subqueryFactory != null)
{
return(subqueryFactory(source, complex));
}
//如果不允许一对多的子查询则抛出异常
throw new DataException($"The specified '{ctx.FullPath}' member is a one-to-many composite(navigation) property that cannot appear in the sorting and specific condition clauses.");
}
source = statement.Join(source, complex, ctx.FullPath);
}
return(source);
});
if (found.IsFailed)
{
throw new DataException($"The specified '{memberPath}' member does not exist in the '{origin.Entity?.Name}' entity and it's inherits.");
}
//输出找到的属性元素
property = found.Property;
//返回找到的源
return(found.Source);
}
