Linq：連接兩個表

Question

在我的WPF網格上，我正在填充以下屬性。 最后兩個來自另一個表。 我想獲得從另一個表的映射規則，其中sourceelementid在交易表等於id的的messagefield表

public List<MessageFieldViewModel> GetAllViewModelMsgFields()
{
    messageFieldVModel = messageField.GetAllMessageField().Select(msgFields => new MessageFieldViewModel
    {
        Id = msgFields.Id,
        Code = msgFields.Code,
        Name = msgFields.Name,
        Position = msgFields.Position,
        Length = msgFields.Length,
        IsMapped = (transactionRuleList.Any(tr=> tr.SourceElementId ==msgFields.Id)),
        MappingRule = transactionRuleList.Where(mapRule => mapRule.MappingRule.Any(tr=> tr.SourceElementId ==msgFields.Id)),
    })
.ToList();
    return messageFieldVModel;
}

但是“映射規則”列會引發錯誤。 有人能幫我嗎 ？

Answer 1

這是一個解決方案：

      transactionRuleList = transationRuleViewModel.GetAllTranslationRules();
        messageFieldVModel = messageField.GetAllMessageField().Select(msgFields => new MessageFieldViewModel
        {
            Id = msgFields.Id,
            Code = msgFields.Code,
            Name = msgFields.Name,
            Position = msgFields.Position,
            Length = msgFields.Length,
            IsMapped = (transactionRuleList.Any(tr => tr.SourceElementId == msgFields.Id)),
            MappingRule = transactionRuleList.Any(mapRule => mapRule.SourceElementId == msgFields.Id)?transactionRuleList.First(mapRule => mapRule.SourceElementId == msgFields.Id).MappingRule:null