将数据集转换为列表

这是我的 C # 代码

Employee objEmp = new Employee();
List<Employee> empList = new List<Employee>();
foreach (DataRow dr in ds.Tables[0].Rows)
{
empList.Add(new Employee { Name = Convert.ToString(dr["Name"]), Age = Convert.ToInt32(dr["Age"]) });
}

它使用循环从数据集创建 List。是否有任何直接的方法或更短的方法或一行代码将数据集转换为 List

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小开
最佳答案

试试这样:

var empList = ds.Tables[0].AsEnumerable()
.Select(dataRow => new Employee
{
Name = dataRow.Field<string>("Name")
}).ToList();
小开

尝试以上将与任何列表类型运行。

  public DataTable ListToDataTable<T>(IList<T> data)
{
PropertyDescriptorCollection props =
TypeDescriptor.GetProperties(typeof(T));
DataTable table = new DataTable();
for (int i = 0; i < props.Count; i++)
{
PropertyDescriptor prop = props[i];
table.Columns.Add(prop.Name, prop.PropertyType);
}
object[] values = new object[props.Count];
foreach (T item in data)
{
for (int i = 0; i < values.Length; i++)
{
values[i] = props[i].GetValue(item);
}
table.Rows.Add(values);
}
return table;
}
小开 
var myData = ds.Tables[0].AsEnumerable().Select(r => new Employee {
Name = r.Field<string>("Name"),
Age = r.Field<int>("Age")
});
var list = myData.ToList(); // For if you really need a List and not IEnumerable
小开

下面是将 DataTable 转换为对象列表的扩展方法:

    public static class Extensions
{
public static List<T> ToList<T>(this DataTable table) where T : new()
{
IList<PropertyInfo> properties = typeof(T).GetProperties().ToList();
List<T> result = new List<T>();


foreach (var row in table.Rows)
{
var item = CreateItemFromRow<T>((DataRow)row, properties);
result.Add(item);
}


return result;
}


private static T CreateItemFromRow<T>(DataRow row, IList<PropertyInfo> properties) where T : new()
{
T item = new T();
foreach (var property in properties)
{
if (property.PropertyType == typeof(System.DayOfWeek))
{
DayOfWeek day = (DayOfWeek)Enum.Parse(typeof(DayOfWeek), row[property.Name].ToString());
property.SetValue(item,day,null);
}
else
{
if(row[property.Name] == DBNull.Value)
property.SetValue(item, null, null);
else
{
if (Nullable.GetUnderlyingType(property.PropertyType) != null)
{
//nullable
object convertedValue = null;
try
{
convertedValue = System.Convert.ChangeType(row[property.Name], Nullable.GetUnderlyingType(property.PropertyType));
}
catch (Exception ex)
{
}
property.SetValue(item, convertedValue, null);
}
else
property.SetValue(item, row[property.Name], null);
}
}
}
return item;
}
}

用途:

List<Employee> lst = ds.Tables[0].ToList<Employee>();

@ itay. b 代码解释: 我们首先使用反射从类 T 中读取所有属性名
然后我们遍历可数据表中的所有行并创建 T 的新对象,
然后我们使用反射来设置新创建的对象的属性。

属性值是从行的匹配列单元格中选取的。

PS: 类属性名和表列名必须相同

小开

试试这个... . 根据您的需要修改代码。

      List<Employee> target = dt.AsEnumerable()
.Select(row => new Employee
{
Name = row.Field<string?>(0).GetValueOrDefault(),
Age= row.Field<int>(1)
}).ToList();
小开

使用数据集中的数据填充数据集，例如存储的 proc 命令

DbDataAdapter adapter = DbProviderFactories.GetFactory(cmd.Connection).CreateDataAdapter();
adapter.SelectCommand = cmd;
DataSet ds = new DataSet();
adapter.Fill(ds);

拿到图式,

string s = ds.GetXmlSchema();

将它保存到一个文件，比如: datetSchema.xsd。为 Schema 生成 C # 类: (在 VS 命令提示符处)

xsd datasetSchema.xsd /c

现在，当您需要将 DataSet 数据转换为可以反序列化的类时(生成的根类的默认名称是 NewDataSet) :

public static T Create<T>(string xml)
{
XmlSerializer serializer = new XmlSerializer(typeof(T));
using (StringReader reader = new StringReader(xml))
{
T t = (T)serializer.Deserialize(reader);


reader.Close();
return t;
}
}


var xml = ds.GetXml();
var dataSetObjects = Create<NewDataSet>(xml);
小开 
                DataSet ds = new DataSet();
ds = obj.getXmlData();// get the multiple table in dataset.


Employee objEmp = new Employee ();// create the object of class Employee
List<Employee > empList = new List<Employee >();
int table = Convert.ToInt32(ds.Tables.Count);// count the number of table in dataset
for (int i = 1; i < table; i++)// set the table value in list one by one
{
foreach (DataRow dr in ds.Tables[i].Rows)
{
empList.Add(new Employee { Title1 = Convert.ToString(dr["Title"]), Hosting1 = Convert.ToString(dr["Hosting"]), Startdate1 = Convert.ToString(dr["Startdate"]), ExpDate1 = Convert.ToString(dr["ExpDate"]) });
}
}
dataGridView1.DataSource = empList;

enter image description here

小开

使用以下代码:

using Newtonsoft.Json;
string JSONString = string.Empty;
JSONString = JsonConvert.SerializeObject(ds.Tables[0]);
小开

添加一个名为“ Helper”的新类，并将该类的属性更改为“ public static”

public static class Helper
{
public static List<T> DataTableToList<T>(this DataTable table) where T : class, new()
{
try
{
List<T> list = new List<T>();


foreach (var row in table.AsEnumerable())
{
T obj = new T();


foreach (var prop in obj.GetType().GetProperties())
{
try
{
PropertyInfo propertyInfo = obj.GetType().GetProperty(prop.Name);
propertyInfo.SetValue(obj, Convert.ChangeType(row[prop.Name], propertyInfo.PropertyType), null);
}
catch
{
continue;
}
}


list.Add(obj);
}


return list;
}
catch
{
return null;
}
}
}

并在后面的代码中访问这个类，如下所示

 DataTable dtt = dsCallList.Tables[0];
List<CallAssignment> lstCallAssignement = dtt.DataTableToList<CallAssignment>();
小开 
 List<GSTEntity.gst_jobwork_to_mfgmaster> ListToGetJwToMfData = new List<GSTEntity.gst_jobwork_to_mfgmaster>();
DataSet getJwtMF = new DataSet();
getJwtMF = objgst_jobwork_to_mfgmaster_BLL.GetDataJobWorkToMfg(AssesseeId, PremiseId,  Fyear,  MonthId, out webex);
if(getJwtMF.Tables["gst_jobwork_to_mfgmaster"] != null)
{


ListToGetJwToMfData = (from master in getJwtMF.Tables["gst_jobwork_to_mfgmaster"].AsEnumerable() select new GSTEntity.gst_jobwork_to_mfgmaster { Partygstin = master.Field<string>("Partygstin"), Partystate =
master.Field<string>("Partystate"), NatureOfTransaction = master.Field<string>("NatureOfTransaction"), ChallanNo = master.Field<string>("ChallanNo"), ChallanDate=master.Field<int>("ChallanDate"),  OtherJW_ChallanNo=master.Field<string>("OtherJW_ChallanNo"),   OtherJW_ChallanDate = master.Field<int>("OtherJW_ChallanDate"),
OtherJW_GSTIN=master.Field<string>("OtherJW_GSTIN"),
OtherJW_State = master.Field<string>("OtherJW_State"),
InvoiceNo = master.Field<string>("InvoiceNo"),
InvoiceDate=master.Field<int>("InvoiceDate"),
Description =master.Field<string>("Description"),
UQC= master.Field<string>("UQC"),
qty=master.Field<decimal>("qty"),
TaxValue=master.Field<decimal>("TaxValue"),
Id=master.Field<int>("Id")


}).ToList();
小开

我无法让尼廷 · 萨万特的答案工作，但我可以修改他的代码为我工作。实际上，我需要使用 GetRuntimeFields 而不是 GetProperties。结果是这样的:

public static class Extensions
{
public static List<T> ToList<T>(this DataTable table) where T : new()
{
IList<FieldInfo> fields = typeof(T).GetRuntimeFields().ToList();
List<T> result = new List<T>();
if (row.Table.Columns.Contains(field.Name))
{
foreach (var row in table.Rows)
{
var item = CreateItemFromRow<T>((DataRow)row, fields);
result.Add(item);
}
}


return result;
}


private static T CreateItemFromRow<T>(DataRow row, IList<FieldInfo> fields) where T : new()
{
T item = new T();


foreach (var field in fields)
{
if (row[field.Name] == DBNull.Value)
field.SetValue(item, null);
else
field.SetValue(item, row[field.Name]);
}
return item;
}
}

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