public IEnumerable <IStatementBase> Build(DataSelectContext context)
{
var statement = new SelectStatement(context.Entity)
{
Paging = context.Paging
};
//生成分组子句
if (context.Grouping != null)
{
this.GenerateGrouping(statement, context.Grouping);
}
//生成查询成员
if (context.Schema != null && !context.Schema.IsEmpty)
{
foreach (var member in context.Schema.Members)
{
//生成数据模式对应的子句
this.GenerateSchema(statement, statement.Table, member);
}
}
//生成条件子句
statement.Where = statement.Where(context.Validate());
//生成排序子句
this.GenerateSortings(statement, statement.Table, context.Sortings);
yield return(statement);
}
private void GenerateGrouping(SelectStatement statement, Grouping grouping)
{
if (grouping == null)
{
return;
}
if (grouping.Keys != null && grouping.Keys.Length > 0)
{
//创建分组子句
statement.GroupBy = new GroupByClause();
foreach (var key in grouping.Keys)
{
var source = statement.From(key.Name, null, out var property);
if (property.IsComplex)
{
throw new DataException($"The grouping key '{property.Name}' can not be a complex property.");
}
statement.GroupBy.Keys.Add(source.CreateField(property));
statement.Select.Members.Add(source.CreateField(property.GetFieldName(out var alias), key.Alias ?? alias));
}
if (grouping.Filter != null)
{
statement.GroupBy.Having = statement.Where(grouping.Filter);
}
}
foreach (var aggregate in grouping.Aggregates)
{
if (string.IsNullOrEmpty(aggregate.Name) || aggregate.Name == "*")
{
statement.Select.Members.Add(
new AggregateExpression(aggregate.Function, Expression.Constant(0))
{
Alias = string.IsNullOrEmpty(aggregate.Alias) ? aggregate.Function.ToString() : aggregate.Alias
});
}
else
{
var source = statement.From(aggregate.Name, null, out var property);
if (property.IsComplex)
{
throw new DataException($"The field '{property.Name}' of aggregate function can not be a complex property.");
}
statement.Select.Members.Add(
new AggregateExpression(aggregate.Function, source.CreateField(property))
{
Alias = string.IsNullOrEmpty(aggregate.Alias) ? aggregate.Name : aggregate.Alias
});
}
}
}
public IEnumerable <IStatementBase> Build(DataSelectContext context)
{
var statement = new SelectStatement(context.Entity)
{
Paging = context.Paging
};
if (statement.Select != null)
{
statement.Select.IsDistinct = context.Options.IsDistinct;
}
//生成分组子句
if (context.Grouping != null)
{
this.GenerateGrouping(context.Aliaser, statement, context.Grouping);
}
//生成查询成员
if (context.Schema != null && !context.Schema.IsEmpty)
{
if (context.Grouping == null)
{
foreach (var member in context.Schema.Members)
{
//生成数据模式对应的子句
this.GenerateSchema(context.Aliaser, statement, statement.Table, member);
}
}
else
{
foreach (var member in context.Schema.Members)
{
if (member.Token.Property.IsComplex)
{
this.GenerateSchema(context.Aliaser, statement, statement.Table, member);
}
}
}
}
//生成条件子句
statement.Where = statement.Where(context.Validate(), context.Aliaser);
//生成排序子句
this.GenerateSortings(context.Aliaser, statement, statement.Table, context.Sortings);
yield return(statement);
}
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);
}