Linq：连接两个表

Question

On my WPF Grid I am populating the following properties. The last two are coming from another table. I would like to get the mapping rule from another table where sourceelementid in the transaction table equals the id of the messagefield table

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;
}

but the Mapping rule column throws error. Can some one help me ?

Answer 1

Here is a solution :

      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