private void GenerateSchema(SelectStatement statement, ISource origin, SchemaMember member)
{
if (member.Ancestors != null)
{
foreach (var ancestor in member.Ancestors)
{
origin = statement.Join(origin, ancestor, member.Path);
}
}
if (member.Token.Property.IsComplex)
{
var complex = (IDataEntityComplexProperty)member.Token.Property;
//一对多的导航属性对应一个新语句（新语句别名即为该导航属性的全称）
if (complex.Multiplicity == DataAssociationMultiplicity.Many)
{
var slave = new SelectStatement(complex.Foreign, member.FullPath)
{
Paging = member.Paging
};
var table = slave.Table;
if (complex.ForeignProperty != null)
{
if (complex.ForeignProperty.IsSimplex)
{
slave.Select.Members.Add(slave.Table.CreateField(complex.ForeignProperty));
}
else
{
table = (TableIdentifier)slave.Join(slave.Table, (IDataEntityComplexProperty)complex.ForeignProperty).Target;
}
}
statement.Slaves.Add(slave);
//为一对多的导航属性增加必须的链接字段及对应的条件参数
foreach (var link in complex.Links)
{
var principalField = origin.CreateField(link.Principal);
principalField.Alias = "$" + member.FullPath + ":" + link.Name;
statement.Select.Members.Add(principalField);
var foreignField = slave.Table.CreateField(link.Foreign);
foreignField.Alias = null;
if (slave.Where == null)
{
slave.Where = Expression.Equal(foreignField, slave.Parameters.Add(link.Name, link.Foreign.Type));
}
else
{
slave.Where = Expression.AndAlso(slave.Where,
Expression.Equal(foreignField, slave.Parameters.Add(link.Name, link.Foreign.Type)));
}
}
//为导航属性增加约束过滤条件
if (complex.HasConstraints())
{
foreach (var constraint in complex.Constraints)
{
slave.Where = Expression.AndAlso(slave.Where,
Expression.Equal(
table.CreateField(constraint.Name),
complex.GetConstraintValue(constraint)));
}
}
if (member.Sortings != null)
{
this.GenerateSortings(slave, table, member.Sortings);
}
if (member.HasChildren)
{
foreach (var child in member.Children)
{
this.GenerateSchema(slave, table, child);
}
}
return;
}
//对于一对一的导航属性，创建其关联子句即可
origin = statement.Join(origin, complex, member.FullPath);
//确保导航属性的外链表的主键都在
if (member.HasChildren)
{
foreach (var key in complex.Foreign.Key)
{
if (!member.Children.Contains(key.Name))
{
member.Append(new SchemaMember(key));
}
}
}
}
else
{
var field = origin.CreateField(member.Token.Property);
//只有数据模式元素是导航子元素以及与当前语句的别名不同（相同则表示为同级），才需要指定字段引用的别名
if (member.Parent != null && !string.Equals(member.Path, statement.Alias, StringComparison.OrdinalIgnoreCase))
{
if (string.IsNullOrEmpty(statement.Alias))
{
field.Alias = member.FullPath;
}
else
{
field.Alias = Zongsoft.Common.StringExtension.TrimStart(member.FullPath, statement.Alias + ".", StringComparison.OrdinalIgnoreCase);
}
}
statement.Select.Members.Add(field);
}
if (member.HasChildren)
{
foreach (var child in member.Children)
{
this.GenerateSchema(statement, origin, child);
}
}
}
private IExpression GenerateAggregate(TContext context, IStatementBase statement, Operand.AggregateOperand aggregate)
{
var entity = this.GetEntity(context);
SelectStatement selection;
IDataEntityProperty property;
FieldIdentifier field;
var parts = aggregate.Member.Split('.', StringSplitOptions.RemoveEmptyEntries);
switch (parts.Length)
{
case 1:
if (!entity.Properties.TryGet(parts[0], out property))
{
throw new DataException($"The specified '{parts[0]}' field does not exist in the '{entity.Name}' entity.");
}
selection = new SelectStatement(entity);
field = selection.Table.CreateField(property);
selection.Select.Members.Add(new AggregateExpression(aggregate.Function, aggregate.Distinct, field));
break;
case 2:
if (!entity.Properties.TryGet(parts[0], out property))
{
throw new DataException($"The specified '{parts[0]}' field does not exist in the '{entity.Name}' entity.");
}
if (property.IsSimplex)
{
throw new DataException($"The specified '{parts[0]}' is a simple property and cannot be navigated.");
}
var complex = (IDataEntityComplexProperty)property;
selection = new SelectStatement(complex.Foreign);
field = selection.Table.CreateField(complex.Foreign.Properties.Get(parts[1]));
selection.Select.Members.Add(new AggregateExpression(aggregate.Function, aggregate.Distinct, field));
var conditions = ConditionExpression.And();
foreach (var link in complex.Links)
{
ISource src = statement.Table;
foreach (var anchor in link.GetAnchors())
{
if (anchor.IsComplex)
{
src = selection.Join(context.Aliaser, selection, (IDataEntityComplexProperty)anchor);
}
else
{
conditions.Add(Expression.Equal(
selection.Table.CreateField(link.ForeignKey),
src.CreateField(anchor)));
}
}
}
selection.Where = conditions;
break;
default:
throw new DataException($"Invalid aggregate member ‘{aggregate.Member}’ because its navigation level is too deep.");
}
if (aggregate.Filter != null)
{
if (selection.Where == null)
{
selection.Where = selection.Where(aggregate.Filter.Flatten(), context.Aliaser);
}
else
{
selection.Where = ConditionExpression.And(selection.Where, selection.Where(aggregate.Filter.Flatten(), context.Aliaser));
}
}
selection.Table.Alias = null;
return(selection);
}