/// <summary>
/// 创建通过主键及值关联的返回数据语句片段。
/// </summary>
/// <param name="unit">内容对象。</param>
/// <param name="target">目标对象。</param>
/// <returns>语句片段。</returns>
internal static SelectFragment SelectReturns(this IContentUnit unit, ISourceFragment target)
{
var data = (ContentBase)unit;
var context = data.GenerateContext;
var select = new SelectFragment(context, target);
select.Members.AddRange(unit.ReturnMembers.Select(a => target.GetMember(a.Metadata)));
select.Where = target.JoinCondition(data.CommitObject, data.Table.Keys);
return(select);
}
/// <summary>
/// 创建通过临时表关联的返回数据语句片段。
/// </summary>
/// <param name="unit">内容对象。</param>
/// <param name="target">目标对象。</param>
/// <param name="temptable">临时表。</param>
/// <returns>语句片段。</returns>
internal static SelectFragment SelectReturns(this IContentUnit unit, ISourceFragment target, TemporaryTableFragment temptable)
{
var data = (ContentBase)unit;
var context = data.GenerateContext;
var select = new SelectFragment(context, target);
select.Members.AddRange(unit.ReturnMembers.Select(a => target.GetMember(a.Metadata)));
select.AddSource(temptable);
target.Join(temptable, data.Table.Keys);
return(select);
}
internal static void GenerateOutput(this IContentUnit unit)
{
if (unit.ReturnMembers.Any())
{
var data = (ContentBase)unit;
var returns = unit.ReturnMembers.Select(a => a.Metadata.Member).ToArray();
var metadata = data.GenerateContext.Metadata.Type(data.Items.ClrType);
var fields = Utility.Array <int>(metadata.PrimaryMembers.Count, -1);
var output = new CollectionOutputInfo(metadata, fields);
for (int i = 0; i < metadata.PrimaryMembers.Count; i++)
{
var member = metadata.PrimaryMembers[i];
fields[i] = Array.IndexOf(returns, member.Member);
}
data.Items.Output = output;
}
}
/// <summary>
/// 根据属性映射表达式创建提交单元。
/// </summary>
/// <param name="data">数据对象。</param>
/// <param name="commitUnit">当前提交单元。</param>
/// <param name="columns">指定的列元数据集合。</param>
/// <param name="content">属性映射表达式。</param>
/// <returns>当前提交单元。</returns>
public static CommitUnitBase CreateCommitUnit(this IContentUnit data, CommitUnitBase commitUnit, IEnumerable <ColumnMetadata> columns, DbExpression content)
{
if (content is DbSelectExpression select && select.Item is DbNewExpression newExpression)
{
foreach (var column in columns)
{
var generator = data.GetValueGenerator(column);
if (newExpression.Members.TryGetValue(column.Member, out DbExpression expression))
{
if (expression is DbMemberExpression memberAccess && memberAccess.Member == column.Member &&
memberAccess.Expression == select.Source.Item)
{
commitUnit.Add(data.CreateCommitUnitMember(column, generator));
}
else
{
commitUnit.Add(data.CreateCommitUnitMember(column, generator, expression));
}
}
