C# 如何检查属性是否返回 null？

Question

我是 C# 新手。我有以下代码:

            XmlNodeList elemList = xmlFile.GetElementsByTagName("Position");

        for (int i = 0; i < elemList.Count; i++)
        {
            string posNumber = elemList[i].Attributes["PosNumber"].Value;
            string posGroup = elemList[i].Attributes["PosGroup"].Value;
            string positionsTypeSK = elemList[i].Attributes["PositionTypeSK"].Value;
            string positionCommercialTypeSK = elemList[i].Attributes["PositionCommercialTypeSK"].Value;
            string positionSK = elemList[i].Attributes["PositionSK"].Value;
            string bookingUnitSK = elemList[i].Attributes["BookingUnitSK"].Value;
            string contentComponentCommSK = elemList[i].Attributes["ContentComponentCommSK"].Value;
            string salesAgentPrice = elemList[i].Attributes["SalesAgentPrice"].Value;

            string bundlePositionSK = (elemList[i].Attributes["BundlePositionSK"] != null).ToString();
            string mainPositionSK = (elemList[i].Attributes["MainPositionSK"] != null).ToString();
            //Now I want the value of the attributes or a empty string here


            listOfNames.Add(new ResultNames(positionSK, posGroup, posNumber, positionCommercialTypeSK, bundlePositionSK, mainPositionSK,
                salesAgentPrice, bookingUnitSK, contentComponentCommSK, positionsTypeSK));
        }
        return listOfNames;

我想检查属性是否返回空值。

我尝试使用 string bundlePositionSK = (elemList[i].Attributes["BundlePositionSK"] != null).ToString();

但在这里它只给我 true 或 false。

我如何检查每个属性/值是否为空？如果它为 null，它应该返回一个空字符串。

Answer 1

您可以使用 null conditional operator :

string posNumber = elemList[i].Attributes["PosNumber"]?.Value ?? String.Empty;