需要找到嵌套的 dto 对象的属性答案

【问题标题】：Need to find the nested dto object's property需要找到嵌套的 dto 对象的属性
【发布时间】：2018-03-06 19:00:03
【问题描述】：

我有以下带有虚拟数据的 DTO。我想从 StandardDTO 对象中找出条目列表的计数：-

public class StandardDTO
{
    public string InternalNotes { get; set; }
    public string CustomerNotes { get; set; }
    public List<Principal> Principals { get; set; }
    public VerificationSummary VerificationSummary{ get; set; }
}

public class Principal
{
    public string PrincipalTitle { get; set; }
    public string PrincipalName { get; set; }
}

public class VerificationSummary
{
    public List<Entry> Entries { get; set; }
    public decimal GrossTotal { get; set; }
    public decimal Total { get; set; }
}

public class Entry
{
    public string PeriodName { get; set; }
    public decimal Amount { get; set; }
}

void Main()
{
    // Need to populate stdDTOObject and childXElement
    int count = GetDTOObjectCount(GetStandardDTOObject(), "VerificationSummary");
    count.Dump();
}

public StandardDTO GetStandardDTOObject()
{
    StandardDTO stdDTOObj = new StandardDTO();
    stdDTOObj.InternalNotes = "InternalNotes";
    stdDTOObj.CustomerNotes = "CustomerNotes";

    List<Principal> lstPrincipal = new List<Principal>();
    Principal pObj = new Principal();
    pObj.PrincipalTitle = "Mr";
    pObj.PrincipalName = "ABC";
    lstPrincipal.Add(pObj);

    pObj = new Principal();
    pObj.PrincipalTitle = "Mrs";
    pObj.PrincipalName = "XYZ";
    lstPrincipal.Add(pObj);

    stdDTOObj.Principals = lstPrincipal;

    VerificationSummary vs = new VerificationSummary();
    List<Entry> lstEntry = new List<Entry>();
    Entry entry = new Entry();
    entry.PeriodName = "Sept17";
    entry.Amount = 1212;
    lstEntry.Add(entry);

    entry = new Entry();
    entry.PeriodName = "Oct17";
    entry.Amount = 12000;
    lstEntry.Add(entry);

    entry = new Entry();
    entry.PeriodName = "Nov17";
    entry.Amount = 1000;
    lstEntry.Add(entry);

    entry = new Entry();
    entry.PeriodName = "Dec17";
    entry.Amount = 2000;
    lstEntry.Add(entry);

    entry = new Entry();
    entry.PeriodName = "Jan18";
    entry.Amount = 2000;
    lstEntry.Add(entry);

    vs.Entries = lstEntry;
    vs.GrossTotal = 5555;
    vs.Total = 10000;
    stdDTOObj.VerificationSummary = vs;
    return stdDTOObj;
}

public int GetDTOObjectCount<T>(T dtoObject, string nodeName)
{
    var dtoObjectType = dtoObject.GetType();
    var objectProperties = GetPropertyInfo(dtoObjectType);

    return GetDTOOBjectCountRecursively(objectProperties, nodeName, dtoObject);
}

public int GetDTOOBjectCountRecursively<T>(IEnumerable<PropertyInfo> objectProperties, string nodeName, T dtoObject)
{
    foreach (PropertyInfo propInfo in objectProperties)
    {
        if (propInfo.Name.Equals(nodeName, StringComparison.OrdinalIgnoreCase))
        {
            var lstDTOItems = propInfo.GetValue(dtoObject) as IList;

            if (lstDTOItems != null)
            {
                return lstDTOItems.Count;
            }
            else
            {
                var objPropInfos = GetPropertyInfo(propInfo.PropertyType);
                //hardcoded the nodeName just for this test.
                return GetDTOOBjectCountRecursively(objPropInfos, "Entries", dtoObject);
            }
        }
    }
    return 0;
}

private IEnumerable<PropertyInfo> GetPropertyInfo(Type type)
{
    return type.GetProperties();
}

问题是我无法在内部递归循环 StandardDTO -> VerificationSummary -> 条目

当 propinfo = "Entries" propinfo 时，它在以下行失败

var lstDTOItems = propInfo.GetValue(dtoObject) as IList;

【问题讨论】：

请发表您的 cmets/advise。它非常紧急。
我正在尝试在 .Net Core 1.1 中实现这一点

标签： c# recursion reflection nested dto

【解决方案1】：

好的。

所以错误是由于以下语句而发生的：

return GetDTOOBjectCountRecursively(objPropInfos, "Entries", dtoObject);

当您发送“条目”时，您需要发送您已进行到的新对象，如下所示：

return GetDTOOBjectCountRecursively(objPropInfos, "Entries",  propInfo.GetValue(dtoObject));

这应该可以解决问题。

另外，要检查通用列表，而不是这样做：

var lstDTOItems = propInfo.GetValue(dtoObject) as IList;

你可以使用这个方法：

private bool IsList(Object obj)
{
    return obj is IList && obj.GetType().IsGenericType;
}

哪个会更健壮。

【讨论】：

【解决方案2】：

为什么要使用反射？

你可以简单地写：

var obj = GetStandardDTOObject();
var count = obj.VerificationSummary.Entries.Count();

【讨论】：