//生成更新表达式。
private void GenerateForUpdateMembers(GenerateContext context, CommitUnitBase unit, UpdateFragment update, ISourceFragment source)
{
foreach (var member in unit.Members)
{
switch (member.ValueType)
{
case ECommitValueType.Constant:
update.SetValue(member.Metadata, source.GetMember(member.Metadata));
break;
case ECommitValueType.Expression:
var exp = (CommitExpressionMember)member;
update.SetValue(member.Metadata, update.CreateExpression(exp.Expression));
break;
}
}
}
/// <summary>
/// 根据属性映射表达式创建提交单元。
/// </summary>
/// <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>
protected CommitUnitBase CreateCommitUnit(CommitUnitBase commitUnit, IEnumerable <ColumnMetadata> columns, DbExpression content)
{
if (content is DbSelectExpression select && select.Item is DbNewExpression newExpression)
{
foreach (var column in columns)
{
var generator = 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(CreateCommitUnitMember(column, generator));
}
else
{
commitUnit.Add(CreateCommitUnitMember(column, generator, expression));
}
}