I have created a class in my ASP.Net project called LitHoldModifications. Here's the code:
[Serializable]
public class LitHoldModifications
{
private Boolean _changed;
private Hashtable _added;
private Hashtable _deleted;
public Boolean Changed
{
get { return _changed; }
set { _changed = value; }
}
public Hashtable Added
{
get { return _added; }
set { _added = value; }
}
public Hashtable Deleted
{
get { return _deleted; }
set { _deleted = value; }
}
public Hashtable Add(String item1, String item2)
{
Added = new Hashtable();
Added.Add(item1, item2);
return Added;
}
public Hashtable Delete(String item1, String item2)
{
Deleted = new Hashtable();
Deleted.Add(item1, item2);
return Deleted;
}
}
The problem I'm having is that I need to be able to Add multiple items to an instance of this class. The code I have to do this is (in an aspx page):
public LitHoldModifications AffectedEmployeeModifications
{
get
{
if (ViewState["AffectedEmployeeModifications"] != null)
return (LitHoldModifications)ViewState["AffectedEmployeeModifications"];
else
return null;
}
set
{
ViewState["AffectedEmployeeModifications"] = value;
}
}
protected void ProcessAffectedviaJavascript()
{
string[] employees = HiddenEmployeesPopup.Value.Split('|');
if (employees.Length>1) {
foreach (string s in employees)
{
if (s.Length > 1)
{
string Anumber = s.Split('#')[0];
string AName = s.Split('#')[1];
ListItem item = new ListItem();
item.Text = AName;
item.Value = Anumber;
lstSelEmployees.Items.Add(item);
//Clear values in temp hidden field:
HiddenEmployeesPopup.Value = "";
AffectedEmployeeModifications.Add(Anumber, AName);
AffectedEmployeeModifications.Changed = true;
}
}
}
When I run my code and get to ProcessAffectedviaJavascript(), the string[] employees is populated with multiple names, but each time the code gets to the line AffectedEmployeeModifications.Add.... a new Hashtable is created and returned by the Add method, so any earlier strings from employees that have been added to AffectedEmployeeModifications are lost. The only way I can think to get around this is to change the Add method to take AffectedEmployeeModifications as a parameter and do this:
public Hashtable Add(Hashtable lhm, String item1, String item2)
{
lhm.Add(item1, item2);
return lhm;
}
and then, in my aspx.cs:
AffectedEmployeeModifications = AffectedEmployeeModifications.Add(AffectedEmployeeModifications, Anumber, AName);
This doesn't seem very OOP-y though, and my OOP skills are clearly wanting. How should I do this?
You should be constructing the objects that your class needs in a constructor for the class. You should add a default constructor like this:
public LitHoldModifications()
{
Added = new Hashtable();
Deleted = new Hashtable();
}
Then you can remove the assignments in your Add() and Delete() methods, because you can assume in these methods that those member variables will already be valid.
I would also recommend changing your Add/Delete methods to returning void. If you want access to the Added/Deleted hashtables, you can just reference that property instead.
var myLitInstance = new LitHoldModifications();
myLitInstance.Add("value1", "value2");
Hashtable tbl = myLitInstance.Added;
Related
I was originally experiencing a problem in my code in which I was unable to "add" an item to a list object. After reviewing the list object however, I realized it only contained a "get", not a "set". So, I'm trying to create a set accessor but I'm having issues:
Here's my original code to add an item to the list object. Currently, nothing gets added:
ClientCompany clientCompany = new ClientCompany();
LocationData urlData = new LocationData();
Location location = urlData.LocationGet(1129); //hardcoded 1129 in for now
clientCompany.Locations.Add(location); //"location" is NOT null, however nothing gets added to Locations object
return clientCompany; //clientCompany.Locations.Count = 0 (it should equal 1)
And here's the current portion of the ClientCompany class I'm having trouble with:
public Dictionary<int, Location> LocationsDict { get; set; }
// List Properties
public List<Location> Locations
{
get { return LocationsDict.Values.ToList(); }
}
I tried including a setter, but I receive the following error:
Cannot convert source type
Systems.Collections.Generic.List<MyCompany.MVC.MyProject.Models.ClientCompany.Location>'
to target type 'Systems.Collections.Generic.Dictionary<int,
MyCompany.MVC.MyProject.Models.ClientCompany.Location>
get { return LocationsDict.Values.ToList(); }
set { LocationsDict = value; }
Any idea what I'm doing wrong?
Thanks
i 'll do something like this:
private Dictionary<int, Location> LocationsDict = new Dictionary<int, Location>();
public void Set(int key, Location value)
{
if (LocationsDict.ContainsKey(key))
LocationsDict[key] = value;
else
LocationsDict.Add(key, value);
}
public Location Get(int key)
{
return LocationsDict.ContainsKey(key) ? LocationsDict[key] : null; }
}
or better (i think) you could use indexer:
public class MyClass
{
private readonly IDictionary<int, Location> LocationsDict = new Dictionary<int, Location>();
public Location this[int key]
{
get { return LocationsDict.ContainsKey(key) ? LocationsDict[key] : null; }
set
{
if (LocationsDict.ContainsKey(key))
LocationsDict[key] = value;
else
LocationsDict.Add(key, value);
}
}
}
var gotest = new MyClass();
gotest[0] = new Location(){....};
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I'm trying to clean up my class using reflection.
private List<String> centers = new List<String>();
private List<String> leftWingers = new List<String>();
private List<String> rightWingers = new List<String>();
private List<String> defencemen = new List<String>();
private List<String> goalies = new List<String>();
private List<String> bench = new List<String>();
public List<String> Centers { get { return centers; } set { centers = value; } }
public List<String> LeftWingers { get { return leftWingers; } set { leftWingers = value; } }
public List<String> RightWingers { get { return rightWingers; } set { rightWingers = value; } }
public List<String> Defencemen { get { return defencemen; } set { defencemen = value; } }
public List<String> Goalies { get { return goalies; } set { goalies = value; } }
public List<String> Bench { get { return bench; } set { bench = value; } }
public String ToString()
{
String output = "";
System.Reflection.PropertyInfo[] properties = this.GetType().GetProperties();
foreach (System.Reflection.PropertyInfo property in properties)
{
int count = 0;
foreach (String value in property)
{
count++;
output += "C" + count + ": " + value + System.Environment.NewLine;
}
}
}
This will not work. I cant seem to be able to loop over items of each property because they are collections. Is there a way to get the contents of the String Lists from the PropertyInfo object?
They are not properties, they are fields,so you need to use GetFields
You need to tell GetFields method that you want to get private
members using BindingFlags, otherwise it will look for public and instance members by default.
var fields = this.GetType().GetFields(BindingFlags.NonPublic | BindingFlags.Instance);
Well, if you really want properties, the first thing is that you do not have properties on your code. You have just some attributes. Change it for properties if it is the case, for sample:
private List<String> centers { get; set; }
private List<String> leftWingers { get; set; }
private List<String> rightWingers { get; set; }
private List<String> defencemen { get; set; }
private List<String> goalies { get; set; }
private List<String> bench { get; set; }
Then you could read them as collections and read values, for sample:
public String ToString()
{
StringBuilder output = new StringBuilder();
System.Reflection.PropertyInfo[] properties = this.GetType().GetProperties();
foreach (System.Reflection.PropertyInfo property in properties)
{
var values = property.GetValue(this, null) as IEnumerable<String>;
if (values != null)
{
int count = 0;
foreach (String value in values)
{
count++;
output.AppendLine(string.Format("C{0}: {1}", count, value));
}
}
}
return output.ToString();
}
Another case is to read the fields and avoid converting it to properties. Look the Selman22's answer!
Your problem can be drastically simplified using Enumerable.Concat, Enumerable.Select and string.Join:
IEnumerable<string> allItems = centers.Concat(leftWingers)
.Concat(rightWingers)
.Concat(defencemen)
.Concat(goalies)
.Concat(bench);
return string.Join
(
Environment.NewLine,
allItems.Select((item, index) => $"C {index + 1}: {item}")
);
These are fields, so you need to use GetFields to obtain them. Please note also that fields returned by reflection are just metadata, they don't contain the data that you need.
To get the data, you need to use the GetValue method to get the field value for the current object.
Then, to be able to enumerate the collection in the field, you need to cast it as IEnumerable<string>.
Here is how it would look like:
public String ToString()
{
String output = "";
var fields = this.GetType().GetFields(BindingFlags.NonPublic | BindingFlags.Instance);
foreach (var field in fields)
{
int count = 0;
foreach (String value in (IEnumerable<string>) field.GetValue(this))
{
count++;
output += "C" + count + ": " + value + System.Environment.NewLine;
}
}
return output;
}
Since you have only 6 collections, you can have a solution that does not involve reflection. Here is an example:
public String ToString()
{
String output = "";
var collections = new[] {centers, leftWingers, rightWingers, defencemen, goalies, bench};
foreach (var field in collections)
{
int count = 0;
foreach (String value in field)
{
count++;
output += "C" + count + ": " + value + System.Environment.NewLine;
}
}
return output;
}
Please consider using a StringBuilder instead of a string. Using a string to concatenate strings will hurt performance.
I have two classes, Customer and Country. Customer has a property called HomeCountry, which i have decorated with a custom attribute called "Lookup" and takes a string parameter "Country". The purpose is, when I am using the Customer class, the item in HomeCountry must exist in the Country class (which happens to be a list).
I am using reflection to iterate the Customer class, it finds the attribute and i want it to check the value in the list of country items. So far I have:
foreach (PropertyInfo _pi in object.GetType().GetProperties()) {
IEnumerable<Attribute> _attrs = _pi.GetCustomAttributes();
foreach (Attribute _a in _attrs) {
Object obj = Activator.CreateInstance(_type, null);
// what goes here?
}
}
I have a method:
public T Populate<T>(params string[] _parameters)
I think i want to do
List<obj> v = populate<obj>();
or
List<typeof(obj)> v = populate<typeof(obj)>();
but obviously nothing works! Can anybody help me ?
Thanks
OK i will try and provide a full example:
I have a CUSTOMER_ORDER class:
public class CUSTOMER_ORDER {
public CUSTOMER_ORDER() {}
[Key(0)]
public string OrderNumber {get;set;}
public MPCCOM_SHIP_VIA ShipVia {get;set;}
}
Then the MPCCOM_SHIP_VIA class:
public class MPCCOM_SHIP_VIA {
public MPCCOM_SHIP_VIA() {}
[Key(0)]
public string ID {get;set;}
public string Description {get;set;}
}
I have a method called Populate< T > which takes a class and then uses reflection to loop all the properties and build a select statement, executes it, and then returns the data and populates the object:
public T Populate<T>(params string[] #Parameters)
{
Type _t = typeof(T);
dynamic _o = Activator.CreateInstance(typeof(T), null);
SqlBuilder _sb = new SqlBuilder();
_sb.Table = string.Format("{0}.{1}", _Owner, _t.Name.ToString());
foreach (PropertyInfo p in _t.GetProperties(Utilities.BindingFlags))
{
if (p.GetMethod.IsPrivate == false) _sb.Fields.Add(p.Name.ToString());
IEnumerable<Attribute> _attrs = p.GetCustomAttributes();
foreach (Attribute _a in _attrs)
{
if (_a.TypeId.ToString().Equals(typeof(Key).FullName))
{
int _position = ((Key)_a).Position;
try
{
string _parameter = #Parameters[_position];
_sb.Where.Add(string.Format("{0} = '{1}'", p.Name, _parameter));
}
catch {}
}
}
}
using (OleDbCommand _cmd = new OleDbCommand())
{
_cmd.Connection = this._cn;
_cmd.CommandText = _sb.SQL;
if (_trn != null) _cmd.Transaction = _trn;
_cmd.CommandType = System.Data.CommandType.Text;
using (OleDbDataReader _reader = _cmd.ExecuteReader())
{
if (_reader.Read())
{
for (int x = 0; x < _reader.FieldCount; x++)
{
foreach (PropertyInfo p in _t.GetProperties(Utilities.BindingFlags))
{
if (p.GetMethod.IsPrivate == false)
{
if (p.Name.Equals(_reader.GetName(x).ToString()))
{
dynamic _val = _reader.GetValue(x);
if (p.ReflectedType.BaseType.Name.Equals(""))
{
// what goes here!
}
try
{
p.GetSetMethod(true).Invoke(_o, new object[] { _val });
}
catch { }
break;
}
}
}
}
}
else
{
throw new DatabaseObjectNotFound(_t.Name.ToString(), string.Join(",",#Parameters));
}
}
}
return (T)_o;
}
So, as i read an order, the source DB gets the key to the MPCCOM_SHIP_VIA in the respective field, i want to call the same Populate method against the MPCCOM_SHIP_VIA object with the key. I hope this makes more sense demonstrating what i want to do. And thanks
After some hunting around, this is the answer i was looking for...
MethodInfo method = typeof(class).GetMethod("Populate");
method = method.MakeGenericMethod(p.PropertyType);
_val = method.Invoke(class, new object[] { _prms });
I guess my issue was i was asking the wrong question!
I have a (string, object) dictionary, object (class) has some values including data type which is defined by enum. I need a GetItemValue method that should return dictionary item's value. So return type must be the type which is defined in item object.
Class Item
{
String Name;
DataValueType DataType;
Object DataValue;
}
private Dictionary<string, Item> ItemList = new Dictionary<string, Item>();
void Main()
{
int value;
ItemList.Add("IntItem", new Item("IntItem", DataValueType.TInt, 123));
value = GetItemValue("IntItem"); // value = 123
}
What kind of solution can overcome this problem?
Best Regards,
You can use Generic Classes
Class Item<T>
{
String Name;
T DataTypeObject;
Object DataValue;
public T GetItemValue()
{
//Your code
return DataTypeObject;
}
}
A better solution would be to introduce an interface that you make all the classes implement. Note that the interface doesn't necessarily have to specify any behavior:
public interface ICanBePutInTheSpecialDictionary {
}
public class ItemTypeA : ICanBePutInTheSpecialDictionary {
// code for the first type
}
public class ItemTypeB : ICanBePutInTheSpecialDictionary {
// code for the second type
}
// etc for all the types you want to put in the dictionary
To put stuff in the dictionary:
var dict = new Dictionary<string, ICanBePutInTheSpecialDictionary>();
dict.add("typeA", new ItemTypeA());
dict.add("typeB", new ItemTypeB());
When you need to cast the objects to their specific types, you can either use an if-elseif-block, something like
var obj = dict["typeA"];
if (obj is ItemTypeA) {
var a = obj as ItemTypeA;
// Do stuff with an ItemTypeA.
// You probably want to call a separate method for this.
} elseif (obj is ItemTypeB) {
// do stuff with an ItemTypeB
}
or use reflection. Depending on how many choices you have, either might be preferrable.
If you have a 'mixed bag' you could do something like this...
class Item<T>
{
public String Name { get; set; }
public DataValueType DataType { get; set; }
public T DataValue { get; set; }
}
class ItemRepository
{
private Dictionary<string, object> ItemList = new Dictionary<string, object>();
public void Add<T>(Item<T> item) { ItemList[item.Name] = item; }
public T GetItemValue<T>(string key)
{
var item = ItemList[key] as Item<T>;
return item != null ? item.DataValue : default(T);
}
}
and use it like...
var repository = new ItemRepository();
int value;
repository.Add(new Item<int> { Name = "IntItem", DataType = DataValueType.TInt, DataValue = 123 });
value = repository.GetItemValue<int>("IntItem");
If you have just a couple types - you're better off with Repository<T>.
I found a solution exactly what I want. Thanks to uncle Google.
Thanks all of you for your kind interest.
public dynamic GetValue(string name)
{
if (OpcDataList[name].IsChanged)
{
OpcReflectItem tmpItem = OpcDataList[name];
tmpItem.IsChanged = false;
OpcDataList[name] = tmpItem;
}
return Convert.ChangeType(OpcDataList[name].ItemValue.Value, OpcDataList[name].DataType);
}
I am abit new in C# and i am trying to insert an object to a CheckedListBox,
so this inserted item will have a title inside the checked list (my object contains a string field inside it which I want to be displayed in the CheckedListBox).
for example this is my class:
public class InfoLayer
{
private string LayerName;
private List<GeoInfo> GeoInfos;
public InfoLayer()
{
LayerName = "New Empty Layer";
GeoInfos = new List<GeoInfo>();
}
public InfoLayer(string LayerName)
{
this.LayerName = LayerName;
GeoInfos = new List<GeoInfo>();
}
public InfoLayer(string LayerName,List<GeoInfo> GeoInfosToClone):this(LayerName)
{
foreach (GeoInfo item in GeoInfosToClone)
{
GeoInfos.Add((GeoInfo)((ICloneable)item).Clone());
}
}
public GeoInfo SearchElement(long id)
{
foreach (GeoInfo info in GeoInfos) // foreach loop running on the list
{
if (info.INFOID == id)
return info; // return the item if we found it
}
return null;
}
public GeoInfo SearchElement(string name)
{
foreach (GeoInfo info in GeoInfos)
{
if (info.INFONAME.CompareTo(name)==0)
return info;
}
return null;
}
public override string ToString()
{
string toReturn = "";
for (int i = 0; i < GeoInfos.Count; i++) // for loop running on the list
{
toReturn += String.Format("{0}\n",GeoInfos[i].ToString()); // piping another geoinfo
}
return toReturn;
}
public string LAYERNAME{get{return LayerName;}}
my class also contains a tostring overrider inside her (not what i want to display)
thanks in advance for your help.
Override ToString() in your class, the class that the object is an instance of.
Edit:
You don't want to display the contents of ToString(). You want to display the LayerName, don't you? Perhaps you should display the values with Databinding instead. Then you can set DisplayMember to your new LAYERNAME property.
I believe this is what you are trying to achieve:
checkedListBox1.Items.Add(yourObject.stringField);
((MyObjectType)checkedListBox1.Items(index)).Name = "whatever"
You will have to know the index of the object you want to change.
You'll just have to override the ToString method in your class so that it returns this Name property value.
public overrides string ToString() {
return Name;
}
It will then display its name when added to your CheckedListbox.