Develop Reference

Generic function to get data from SqlDataReader

I'm creating a generic application to get all the data from different SQL Server tables.
I have a generic function that convert the SqlDataReader to a list:
public static List<T> MapToList<T>(this SqlDataReader dr) where T : new()
{
List<T> RetVal = null;
var Entity = typeof(T);
var PropDict = new Dictionary<string, PropertyInfo>();
try
{
if (dr != null && dr.HasRows)
{
RetVal = new List<T>();
var Props = Entity.GetProperties(BindingFlags.Instance | BindingFlags.Public);
PropDict = Props.ToDictionary(p => p.Name.ToUpper(), p => p);
while (dr.Read())
{
T newObject = new T();
for (int Index = 0; Index < dr.FieldCount; Index++)
{
if (PropDict.ContainsKey(dr.GetName(Index).ToUpper()))
{
var Info = PropDict[dr.GetName(Index).ToUpper()];
if ((Info != null) && Info.CanWrite)
{
var Val = dr.GetValue(Index);
Info.SetValue(newObject, (Val == DBNull.Value) ? null : Val, null);
}
}
}
RetVal.Add(newObject);
}
}
}
catch (Exception)
{
throw;
}
return RetVal;
}
Now suppose I have this class for my data:
public partial class User
{
public int Id { get; set; }
public string Name { get; set; }
}
I can fetch my data from the table something like this:
const string GetAreasQuery = "select id, name from dbo.user";
SqlDataReader dr = DoQueryToDB(GetAreasQuery);
List<User> userList = dr.MapToList<User>();
Now, I have n different classes like User (Classroom and so on) and I don't want to write the code above for each class I have. I would like to create a generic GetData to retrieve those information:
public List<T> GetData<T> (string Query_)
{
SqlDataReader dr = DataReader(Query_);
List<T> data = new List<T>();
data = dr.MapToList<T>();
return data;
}
where T can be User, Classroom and so on...
I tried this solution but I always have to specify the type:
public object GetData(string Query_, Type type)
{
SqlDataReader dr = DataReader(Query_);
if (type == typeof(User))
{
List<User> data = new List<User>();
data = dr.MapToList<User>();
return data;
}
else if (..)
{}
return null;
}
I'm trying different possibilities but I always obtain an error in GetData<T> function. More precisely in MapToList<T> like: T should be a non abstract type or public constructor without parameters.

You should add a contraint to the method GetData in order to achieve the same constraint level that is found in MapToList, which requires T to have a empty constructor
public List<T> GetData<T>(string Query_) where T : new()
{
SqlDataReader dr = DataReader(Query_);
return dr.MapToList<T>();
}

How to extract particular properties from generic list based on property name sent as string array?

I have a Generic List of type List<InstanceDataLog> which has huge number of properties in it. I want to pass names of a few properties to a method and want to extract a refined List from within this list.
public void Export(string col) //a,b,c
{
string [] selectedcol = col.Split(',');
var grid = new GridView();
var data = TempData["InstanceDataList"];
List<InstanceDataLog> lst = new List<InstanceDataLog>();
List<EToolsViewer.APIModels.InstanceDataLog> lstrefined = new List<InstanceDataLog>();
lst= (List<EToolsViewer.APIModels.InstanceDataLog>)TempData["InstanceDataList"];
var r= lst.Select(e => new {e.a, e.b}).ToList();// I would like to replace these hardcoded properties with names of properties present in `selectedcol `
grid.DataSource =r;
grid.DataBind();
}
To clear things up further, suppose InstanceDataLog has 5 properties : a,b,c,d,e I would like pass a,b and be able to extract a new list with only properties a,b
EDIT:
$('#export').mousedown(function () {
window.location = '#Url.Action("Export", "TrendsData",new { col = "a,b,c" })';
});

You could use such method to get properties:
private object getProperty(EToolsViewer.APIModels.InstanceDataLog e, string propName)
{
var propInfo =typeof(EToolsViewer.APIModels.InstanceDataLog).GetProperty(propName);
return propInfo.GetValue(e);
}
and with another function you could get all properties you want:
private dynamic getProperties(string[] props, EToolsViewer.APIModels.InstanceDataLog e )
{
var ret = new ExpandoObject() as IDictionary<string, Object>;;
foreach (var p in props)
{
ret.Add(p, getProperty(e, p));
}
return ret;
}
The problem occurs if you try to assign DataSource with expando object. Solution is described hier:
Binding a GridView to a Dynamic or ExpandoObject object
We do need one more method:
public DataTable ToDataTable(IEnumerable<dynamic> items)
{
var data = items.ToArray();
if (data.Count() == 0) return null;
var dt = new DataTable();
foreach (var key in ((IDictionary<string, object>)data[0]).Keys)
{
dt.Columns.Add(key);
}
foreach (var d in data)
{
dt.Rows.Add(((IDictionary<string, object>)d).Values.ToArray());
}
return dt;
}
and use it:
var r = lst.Select(e => getProperties(selectedcol, e)).ToList();
grid.DataSource = ToDataTable(r);
The same thing, but ready to run for LinqPad:
void Main()
{
var samples = new[] { new Sample { A = "A", B = "B", C = "C" }, new Sample { A = "A1", B = "B2", C = "C1" } };
var r = samples.Select(e => getProperties(new[] {"A", "C", "B"}, e)).ToList();
r.Dump();
}
private object getProperty(Sample e, string propName)
{
var propInfo = typeof(Sample).GetProperty(propName);
return propInfo.GetValue(e);
}
private dynamic getProperties(string[] props, Sample e)
{
var ret = new ExpandoObject() as IDictionary<string, Object>; ;
foreach (var p in props)
{
ret.Add(p, getProperty(e, p));
}
return ret;
}
public class Sample
{
public string A { get; set;}
public string B { get; set;}
public string C { get; set;}
}
With output:

To keep compiler type/name checking suggest to pass a Func<InstanceDataLog, TResult> instead of array of names
public void Export<TResult>(Func<InstanceDataLog, TResult> selectProperties)
{
var grid = new GridView();
var data = TempData["InstanceDataList"];
var originalList = (List<InstanceDataLog>)TempData["InstanceDataList"];
var filteredList = originalList.Select(selectProperties).ToList();
grid.DataSource = filteredList;
grid.DataBind();
}
Then use it:
Export(data => new { Id = data.Id, Name = data.Name });

SetValue with generic type T

I have this function:
the variable c obtains all the properties of my class <T>
in this case:
c ->
Id
Key
Value
public List<T> ReadStoreProceadure<T>(string storeName)
{
var result = new List<T>();
var instance = (T) Activator.CreateInstance(typeof (T), new object[] {});
var c = typeof (T);
var data = DataReader.ReadStoredProceadures(_factibilidad, storeName); // This part is returning verified data and it's ok
while (data.Read())
{
if (data.HasRows)
{
foreach (var item in c.GetProperties())
{
//item.SetValue(c, item.Name, null);
}
}
}
}
How I can add these values to my instance instance and add it to my result variable?
It's possible?

I've created an extension method for IDataReader that does essentially what I believe you're trying to do:
public static List<T> ToList<T>(this IDataReader dr) where T: new()
{
var col = new List<T>();
var type = typeof(T);
var props = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
while (dr.Read())
{
var obj = new T();
for (int i = 0; i < dr.FieldCount; i++)
{
string fieldName = dr.GetName(i);
var prop = props.FirstOrDefault(x => x.Name.ToLower() == fieldName.ToLower());
if (prop != null)
{
if (dr[i] != DBNull.Value)
{
prop.SetValue(obj, dr[i], null);
}
}
}
col.Add(obj);
}
dr.Close();
return col;
}
However, you'll notice I've chosen to work the from the other way around. Instead of iterating the type's properties and fetching them from the DataReader, I iterate the DataReader columns and check for a matching property on the type. You should be able to quickly modify this to fit your data retrieval scheme.

Port of BeanUtils to .NET

I have a system using dynamic run-time configuration of dynamically loaded types.
The system is loading Types based on XML and creating instances. It then reads "properties" from the XML file, setting these properties on the created instance. At this time, it works on simple properties directly on the instance, however, these types can have a hierarchy of settings unknown to the calling part.
I'm looking for a utils-library similar to Java BeanUtils [http://commons.apache.org/proper/commons-beanutils/]. I would want it to be able to do something like this (pseudo code):
Util.SetProperty(someInstance, "property1.property2, someValue);
Or perhaps with extensions:
someInstance.SetProperty("property1.property2, someValue);
And the reverse with Get of course.
Note that BeanUtils has it's own style of describing properties so it works for most types of properties, including lists.
Anything, or perhaps suggestions on different approach to the problem?

Here is a helper class which supports Lists, Dictionaries and nested Properties, you should extend it if you need to support multiple indexers (very rare cases).
public static class Helper
{
public static void SetProperty(object instance, string propery, object value)
{
const BindingFlags flags = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic;
var properties = propery.Split('.');
var type = instance.GetType();
object[] index = null;
PropertyInfo property = null;
for (var i = 0; i < properties.Length; i++)
{
var indexValue = Regex.Match(properties[i], #"(?<=\[)(.*?)(?=\])").Value;
if (string.IsNullOrEmpty(indexValue))
{
property = type.GetProperty(properties[i], flags);
index = null;
}
else
{
property =
type.GetProperty(properties[i].Replace(string.Format("[{0}]", indexValue), string.Empty),
flags);
index = GetIndex(indexValue, property);
}
if (i < properties.Length - 1)
instance = property.GetValue(instance, index);
type = instance.GetType();
}
property.SetValue(instance, value, index);
}
public static object GetProperty(object instance, string propery)
{
const BindingFlags flags = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic;
var properties = propery.Split('.');
var type = instance.GetType();
foreach (var p in properties)
{
var indexValue = Regex.Match(p, #"(?<=\[)(.*?)(?=\])").Value;
object[] index;
PropertyInfo property;
if (string.IsNullOrEmpty(indexValue))
{
property = type.GetProperty(p, flags);
index = null;
}
else
{
property =
type.GetProperty(p.Replace(string.Format("[{0}]", indexValue), string.Empty),
flags);
index = GetIndex(indexValue, property);
}
instance = property.GetValue(instance, index);
type = instance.GetType();
}
return instance;
}
private static object[] GetIndex(string indicesValue, PropertyInfo property)
{
var parameters = indicesValue.Split(',');
var parameterTypes = property.GetIndexParameters();
var index = new object[parameterTypes.Length];
for (var i = 0; i < parameterTypes.Length; i++)
index[i] = parameterTypes[i].ParameterType.IsEnum
? Enum.Parse(parameterTypes[i].ParameterType, parameters[i])
: Convert.ChangeType(parameters[i], parameterTypes[i].ParameterType);
return index;
}
}
and here is some Examples:
public enum Qwerty
{
Q,W,E,R,T,Y
}
class A
{
private int[,] _array=new int[10,10];
public B PropertyB { get; set; }
public int this[int i, int j]
{
get { return _array[i, j]; }
set { _array[i, j] = value; }
}
}
class B
{
public int Value { get; set; }
}
Nested Properties:
var a = new A { PropertyB = new B() };
Helper.SetProperty(a, "PropertyB.Value", 100);
var value = Helper.GetProperty(a, "PropertyB.Value");
Indexer (with multiple index):
var a = new A { PropertyB = new B() };
Helper.SetProperty(a, "Item[1,1]", 100);
var value = Helper.GetProperty(a, "Item[1,1]");
Lists:
var list = new List<int>() { 0, 1, 2, 3, 4 };
Helper.SetProperty(list, "Item[2]", 200);
var value = Helper.GetProperty(list, "Item[2]");
Nested Properties with Lists:
var list = new List<A>() { new A { PropertyB = new B() } };
Helper.SetProperty(list, "Item[0].PropertyB.Value", 75);
var value = Helper.GetProperty(list, "Item[0].PropertyB.Value");
Dictionaries:
var dic = new Dictionary<int, A> { { 100, new A { PropertyB = new B() } } };
var newA = new A { PropertyB = new B() { Value = 45 } };
Helper.SetProperty(dic, "Item[100]", newA);
var value = Helper.GetProperty(dic, "Item[100].PropertyB.Value");
Dictionaries with Enumeration as Key:
var dic = new Dictionary<Qwerty, A> { { Qwerty.Q, new A { PropertyB = new B() } } };
var newA = new A { PropertyB = new B() { Value = 45 } };
Helper.SetProperty(dic, "Item[Q]", newA);
var value = Helper.GetProperty(dic, "Item[Q].PropertyB.Value");
Enumeration as Value:
var list = new List<Qwerty>() { Qwerty.Q, Qwerty.W, Qwerty.E, Qwerty.R, Qwerty.T, Qwerty.Y };
Helper.SetProperty(list, "Item[2]", Qwerty.Q);
var value = Helper.GetProperty(list, "Item[2]");

Convert DataSet to List

Here is my c# code
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"]) });
}
It uses a loop to create a List from a dataset.Is there any direct method or shorter method or one line code to convert dataset to list

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

Here's extension method to convert DataTable to object list:
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;
}
}
usage:
List<Employee> lst = ds.Tables[0].ToList<Employee>();
#itay.b
CODE EXPLAINED:
We first read all the property names from the class T using reflection
then we iterate through all the rows in datatable and create new object of T,
then we set the properties of the newly created object using reflection.
The property values are picked from the row's matching column cell.
PS: class property name and table column names must be same

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

Use the code below:
using Newtonsoft.Json;
string JSONString = string.Empty;
JSONString = JsonConvert.SerializeObject(ds.Tables[0]);

Try this....modify the code as per your needs.
List<Employee> target = dt.AsEnumerable()
.Select(row => new Employee
{
Name = row.Field<string?>(0).GetValueOrDefault(),
Age= row.Field<int>(1)
}).ToList();

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;

Add a new class named as "Helper" and change the property of the class to "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;
}
}
}
and access this class in your code behind as like below
DataTable dtt = dsCallList.Tables[0];
List<CallAssignment> lstCallAssignement = dtt.DataTableToList<CallAssignment>();

Fill the dataset with data from, say a stored proc command
DbDataAdapter adapter = DbProviderFactories.GetFactory(cmd.Connection).CreateDataAdapter();
adapter.SelectCommand = cmd;
DataSet ds = new DataSet();
adapter.Fill(ds);
Get The Schema,
string s = ds.GetXmlSchema();
save it to a file say: datasetSchema.xsd. Generate the C# classes for the Schema: (at the VS Command Prompt)
xsd datasetSchema.xsd /c
Now, when you need to convert the DataSet data to classes you can deserialize (the default name given to the generated root class is 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);

I couldn't get Nitin Sawant's answer to work, but I was able to modify his code to work for me. Essentially I needed to use GetRuntimeFields instead of GetProperties. Here's what I ended up with:
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;
}
}

Try the above which will run with any list type.
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;
}

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();