Question

在下面的效用函数（列表到数据表）中，如何排除某些列表成员。

喜欢，我不想发送2个属性“UniqueKey”＆amp; “PointToPointData”到下面的实用方法，

public class PointDataClone
{
    public int DataId { get; set; }
    public string UniqueKey { get; set; }
    public int Count { get; set; }
    public List<PointToPointData> PointToPointData { get; set; }
}

效用函数，

public static DataTable ToDataTable<T>(this List<T> iList)
    {
        DataTable dataTable = new DataTable();
        PropertyDescriptorCollection propertyDescriptorCollection = TypeDescriptor.GetProperties(typeof(T));
        for (int i = 0; i < propertyDescriptorCollection.Count; i++)
        {
            PropertyDescriptor propertyDescriptor = propertyDescriptorCollection[i];
            Type type = propertyDescriptor.PropertyType;

            if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>))
                type = Nullable.GetUnderlyingType(type);

            dataTable.Columns.Add(propertyDescriptor.Name, type);
        }
        object[] values = new object[propertyDescriptorCollection.Count];
        foreach (T iListItem in iList)
        {
            for (int i = 0; i < values.Length; i++)
            {
                values[i] = propertyDescriptorCollection[i].GetValue(iListItem);
            }
            dataTable.Rows.Add(values);
        }
        return dataTable;
    }

Answer 1

创建属性

[AttributeUsage(AttributeTargets.Method | AttributeTargets.Property | AttributeTargets.Field | AttributeTargets.Parameter, AllowMultiple = false)]
public class DontShowMe : Attribute
{
}

然后，您可以使用该属性为您的班级注释

public class PointDataClone
{
    public int DataId { get; set; }
    [DontShowMe]
    public string UniqueKey { get; set; }
    public int Count { get; set; }
    [DontShowMe]
    public List<PointToPointData> PointToPointData { get; set; }
}

并修改您的函数以查询属性。您将需要一个额外的使用声明

using System.ComponentModel;

将此行添加到循环

if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>)) type = Nullable.GetUnderlyingType(type);

// test attribute to see if it is shown
if (propertyDescriptor.Attributes.Contains(new DontShowMe())) continue;

dataTable.Columns.Add(propertyDescriptor.Name, type);

您现在必须处理这样一个事实，即您的对象将具有比数据表具有列更多的属性。我会留给你管理那个小细节。

希望这有帮助，

马克

Answer 2

请在下面找到代码。我传递了字符串列表以排除属性名称。参见下面的代码。

 public static DataTable ToDataTableVendorExp<T>(List<T> items,List<string> ExcludeColumnName)
    {
        DataTable dataTable = new DataTable(typeof(T).Name);

        //Get all the properties
        PropertyInfo[] Props = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance).Where(a => a.PropertyType != typeof(System.Object)).Cast<PropertyInfo>().ToArray();
        List<int> lstIgnoreIndex = new List<int>();
        int colIndex = 0;
        foreach (PropertyInfo prop in Props)
        {

            //Defining type of data column gives proper data table 
            var type = (prop.PropertyType.IsGenericType && prop.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>) ? Nullable.GetUnderlyingType(prop.PropertyType) : prop.PropertyType);
            //Setting column names as Property names
            string dtcolumname = prop.Name;
            //check if property name of list dont need to export then ignore.
            if (ExcludeColumnName != null && ExcludeColumnName.IndexOf(dtcolumname) >= 0)
            {
                lstIgnoreIndex.Add(colIndex);
            }
            else
            {
                if (Attribute.IsDefined(prop, typeof(DisplayNameRptAttribute)))
                {
                    var attrvalue = (DisplayNameRptAttribute)prop.GetCustomAttribute(typeof(DisplayNameRptAttribute));
                    dtcolumname = attrvalue.GetName();
                }

                dataTable.Columns.Add(dtcolumname, type);
            }
            colIndex++;
        }
        //if ignore 3 properties out of 10 then only 7 required.
        int totlaproplength = Props.Length;
        if (lstIgnoreIndex.Count > 0)
            totlaproplength = totlaproplength - lstIgnoreIndex.Count;

        foreach (T item in items)
        {
            var values = new object[totlaproplength];
            for (int i = 0; i < Props.Length; i++)
            {
                if (lstIgnoreIndex.IndexOf(i) >= 0)
                    continue;
                //inserting property values to datatable rows
                values[i] = Props[i].GetValue(item, null);
                if (Props[i].ToString() == "System.DateTime Date")
                {
                    values[i] = String.Format("{0:MM/dd/yyyy}", (Props[i].GetValue(item, null)));
                }
            }
            dataTable.Rows.Add(values);
        }
        //put a breakpoint here and check datatable
        return dataTable;
    }

如何排除一些列表属性以生成数据表

2 个答案: