Develop Reference

What's the proper way to set up a class to initialize public variables in c#?

I have created the class at the bottom in c#. This class is referenced by webservices to determine user accesses, like this:
[WebMethod]
public List<FAFSA> getFAFSA(string pageID)
{
formValues fv = new formValues();
string personID = fv.personID;
List<FAFSA> lf = new List<FAFSA>();
if (fv.secBlur == "no_secBlur")
{
FAFSA f = new FAFSA();
f.fafsaCheck = "0";
lf.Add(f);
}
...
}
I'm trying to add the two variables fafsa and staff. The method getSecBlur() is returning all three values from my database for secBlur, fafsa, and staff. So how do I set up this class, so that the SecBlur method is only called once but populates all three of my variables so that they can be used in webservice calls? It will not work the way it is now because it says fafsa and staff need to be static, but if I make them static, then in the webservices it says that the members must be accessed with an instance reference.
Sorry if this isn't worded to well, but I'm new to this and still trying to learn...
public class formValues : System.Web.Services.WebService
{
public string userName = getUserName();
public string firstName = getFirstName();
public string personID = getPersonID();
public int fafsa = 0;
public int staff = 0;
public string secBlur = getSecBlur();
private static string getUserDataString(int ix)
{
string retValue = "";
if (HttpContext.Current.Request.IsAuthenticated)
{
HttpCookie authCookie = HttpContext.Current.Request.Cookies[FormsAuthentication.FormsCookieName];
if (authCookie != null)
{
FormsAuthenticationTicket ticket = FormsAuthentication.Decrypt(authCookie.Value);
if (ticket != null)
{
string[] userData = { "" };
char[] delimiterChar = { '|' };
userData = ticket.UserData.Split(delimiterChar);
if (userData.Length > 1)
retValue = userData[ix];
else
{
FormsAuthentication.SignOut();
string redirUrl = "/DMC/loginNotFound.html";
HttpContext.Current.Response.Redirect(redirUrl, false);
}
}
}
}
return retValue;
}
private static string getUserName()
{
//This retrieves the person logged into windows/active directory
WindowsPrincipal wp = new WindowsPrincipal(WindowsIdentity.GetCurrent());
//string[] fullUsername = wp.Identity.Name.Split('\\');
string fullUsername = wp.Identity.Name;
return fullUsername;
}
private static string getFirstName()
{
string firstName = getUserDataString(1);
return firstName;
}
private static string getPersonID()
{
string personID = getUserDataString(0);
return personID;
}
private static string getSecBlur()
{
string secBlur = "no_secBlur";
string mySQL = "exec get_UserAdminStatus #personID";
string cf = System.Configuration.ConfigurationManager.ConnectionStrings["DistrictAssessmentDWConnectionString"].ConnectionString;
SqlConnection connection = new SqlConnection(cf);
SqlCommand command = new SqlCommand(mySQL, connection);
command.Parameters.AddWithValue("#personID", getUserDataString(0));
connection.Open();
SqlDataReader dr = command.ExecuteReader();
DataTable dt = new DataTable();
dt.Load(dr);
connection.Close();
if (dt.Rows.Count > 0)
{
if (dt.Rows[0]["secBlur"].ToString() == "1")
secBlur = "secBlur";
fafsa = Convert.ToInt32(dt.Rows[0]["fafsa"]);
staff = Convert.ToInt32(dt.Rows[0]["staff"]);
}
return secBlur;
}
}

If you give any class static, public values the so called "Static" (or type) Constructor will be called to do the initialization work before any access is done: https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/static-constructors
Another common way to do initlizsation or define default values, is to use the Factory Pattern. Afaik the Graphics Class in XNA has to adapt depending if you run ona X-Box or PC, so it uses the Factory Pattern.
Of coruse with Web(anything) there is the whole issue with variable Scope, even for Statics. Much less local variables.

How to get a specific string out of a database with C# using a parameter that can change in layer model

I need to make a helpdesk form for my end of year task and I'm stuck.
The task requires me to load the solution of a specific problem that the user selects via a combobox. My implementation needs to separated into layers like business persist and so on.
The code that I wrote to solve this didn't work (EXPLAIN WHY HERE). I have made a few attempts at it and have included them below.
First Attempt:
For my first attempt, I have written the following code to load the solution to the selected problem from the database:
public List<HelpDesk> getOplossing()
{
List<HelpDesk> lijst = new List<HelpDesk>();
MySqlConnection conn = new MySqlConnection(_connectionstring);
MySqlCommand cmd = new MySqlCommand("SELECT Oplosing from tblhelpdesk where Probleem = #probleem" , conn);
cmd.Parameters.Add(new MySqlParameter("#probleem",
getProbleem().ToString()));
conn.Open();
MySqlDataReader datareader = cmd.ExecuteReader();
while (datareader.Read())
{
HelpDesk hlpdsk = new HelpDesk(
datareader["Oplosing"].ToString());
lijst.Add(hlpdsk);
}
conn.Close();
return lijst;
}
And in the controller I called it like this:
public List<HelpDesk> getOplossing()
{
return _persistcode.getOplossing();
}
Attempt 2:
This is what I wrote for my second attempt.
public string getOplossing()
{
MySqlConnection conn = new MySqlConnection(_connectionstring);
MySqlCommand cmd = new MySqlCommand("SELECT Oplosing from tblhelpdesk", conn);
conn.Open();
string oplossing;
oplossing = cmd.ExecuteScalar().ToString();
conn.Close();
return oplossing;
}
Again in the controller:
public string getOplossing()
{
return _persistcode.getOplossing();
}
My entire HelpDesk class:
And the class HelpDesk looks like this: (I provided the whole class so you guys can have a gander at all the problem :/ )
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace GPDeBruykerSander_Domain.Business
{
public class HelpDesk
{
private int _id;
private Boolean _categorie; //Hardware= True en Software= False
private DateTime _datumProbleem;
private string _probleem;
private DateTime _datumOplossing;
private string _oplossing;
public int ID
{
get { return _id; }
set { _id = value; }
}
public override string ToString()
{
return Probleem;
}
public Boolean Categorie
{
get { return _categorie; }
set { _categorie = value; }
}
public DateTime DatumProbleem
{
get { return _datumProbleem; }
set { _datumProbleem = value; }
}
public string Probleem
{
get { return _probleem; }
set { _probleem = value; }
}
public DateTime DatumOplossing
{
get { return _datumOplossing; }
set { _datumOplossing = value; }
}
public string Oplossing
{
get { return _oplossing; }
set { _oplossing = value; }
}
public HelpDesk (int id, Boolean categorie, DateTime datumProbleem, string probleem, DateTime datumOplossing, string oplossing)
{
_id = id;
_categorie = categorie;
_datumProbleem = datumProbleem;
_probleem = probleem;
_datumOplossing = datumOplossing;
_oplossing = oplossing;
}
public HelpDesk(Boolean categorie, DateTime datumProbleem, string probleem, DateTime datumOplossing, string oplossing)
{
_categorie = categorie;
_datumProbleem = datumProbleem;
_probleem = probleem;
_datumOplossing = datumOplossing;
_oplossing = oplossing;
}
public HelpDesk(DateTime datumProbleem, Boolean categorie, string probleem)
{
_datumProbleem = datumProbleem;
_categorie = categorie;
_probleem = probleem;
}
public HelpDesk(DateTime datumOplossing, string oplossing)
{
_datumOplossing = datumOplossing;
_oplossing = oplossing;
}
public HelpDesk(string probleem)
{
_probleem = probleem;
}
}
}
I hope somebody can help me find the solution because I'm stuck :/

You were closer to solving your problem in your first attempt, so I will help you with that. But since you haven't actually provided any reasons as to why your code doesn't work (errors thrown by the application, etc.), I can only take a stab at potential issues I see in your code.
Looking at your MySQL query: SELECT Oplosing from tblhelpdesk where Probleem = #probleem, I would say that you are missing quotes around #probleem. So this query should look like this:
SELECT Oplosing from tblhelpdesk where Probleem = '#probleem'
I would also make the following suggestions:
Suggestion 1: Make getProbleem() method actually return a string, so you don't have to call ToString() on it. You haven't provided the implementation of this method so I can only assume the return type is not a string. If the return type is a string the ToString() is completely redundant here.
Suggestion 2:
I would also suggestion is that you pass the problem string as a parameter to getOplossing(), so that the database code is encapsulated better. For example:
public List<HelpDesk> getOplossing(string probleem)
{
...
cmd.Parameters.Add(new MySqlParameter("#probleem", probleem));
...
}
And your controller will call it like so:
public List<HelpDesk> getOplossing()
{
string probleem = getProbleem().ToString();
return _persistcode.getOplossing(probleem);
}

How to create a single object and use values in different events?

I am creating a program with two forms(register and view).
The view form will read a single record from a table(database), and then you can edit or delete the record. I am creating a class for this program, and for one of the constructors it will get the search ID, First name and last name from the view form and then there is a method which will search through the table for the record(using search ID, OR firstname and lastname) and will assign the variables inside the class, and I want to use THOSE variables for my edit and delete methods, but the problem is when I try to create a public object of the class which would be used across all my events, using 'this' keyword, it says that this doesn't exist in the current context, but whenever I create an object in each event it will recognize 'this' keyword, but I won't be able to use the class variables assigned from the search method. This is my constructor and search method for the class
public ASystem(searchSHD search)
{
searchHID = search.searchHID;
search_FName = search.searchFName;
search_LName = search.searchLName;
}
public String searchHID;
public String search_FName;
public String search_LName;
public String HID;
public String First_Name;
public String Full_Name;
public String query;
public String Last_Name;
public String PhoneNum;
public String Country;
public String DOB;
public String Experience;
public void Search()
{
using (OleDbConnection db_connection = new OleDbConnection(#"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\KAZEM\Documents\Hairsalon\employees.accdb;
Persist Security Info=False;"))
{
if (searchHID == "")
{
query = "SELECT * FROM Hairdresser where First_Name = #FName AND Last_Name = #LName";
}
else
{
query = "SELECT * FROM Hairdresser where HID = #HID";
}
using (OleDbCommand db_command = new OleDbCommand(query, db_connection))
{
db_command.Parameters.Add("#HID", searchHID);
db_command.Parameters.Add("#FName", search_FName);
db_command.Parameters.Add("#LName", search_LName);
db_connection.Open();
OleDbDataReader reader = db_command.ExecuteReader();
reader.Read();
HID = reader.GetValue(0).ToString();
First_Name = reader.GetString(1);
Last_Name = reader.GetString(2);
Full_Name = First_Name + " " + Last_Name;
Country = reader.GetString(4);
PhoneNum = reader.GetString(5);
DOB = (Convert.ToDateTime(reader.GetValue(3))).ToString();
Experience = reader.GetValue(6).ToString();
}
}
}

you can create your own event through creating a class which is derived of EventArgs, that like:
class yourEventArgs:EventArgs
{
public yourEventArgs(object yourValues)
{
Value = yourValues;
}
//Create your properties like below
public object Value { get; set; }
}
after that you need to create an eventhandler:
public event EventHandler<yourEventArgs> YourEventName;
for raising the event you use:
if(YourEventName!=null)
{YourEventName(this,new yourEventArgs(yourValue));}
then you can add to your eventhandler your method through (the code which should be executed if you raise the event)
YourEventName+=((object o,yourEventArgs e)=> {/*-Insert Code here-*/});
//or
YourEventName+=on_yourEvent;
private void on_yourEvent(object o,yourEventArgs e)
{
/*-Insert your Code here- */
}
I hope that's what you want.

Retrieving info from database only show me one field

I have a problem retrieving information from the database.
I have a function
public List<string> Selectquery(string sql)
{
return GetContext().ExecuteQuery<string>(sql).ToList();
}
where the variable sql:
var sql = "SELECT s.UserName AS username, st.Name AS status_name, c.FirstName FROM client c JOIN Suser s ON (c.UserID=s.ID) JOIN Status AS st ON (c.StatusID=st.ID) GROUP BY s.UserName,st.Name";
In the other file I call the function it is like this:
List<string> SUsers = _DAO.Selectquery(sql);
When I see the result with a breakpoint, and make a foreach for example:
foreach (string su in SUsers)
{
String str = su;
}
I only see the username, and the others fields disappear. I have change List for IEnumerable and the result is the same.
So I don't know whats is happening.
I would Appreciate your help.
Thank You.

Create a class like this:
public class clients{
private string username;
public string Username
{
get
{
return username;
}
set
{
username = value;
}
}
private string status_name;
public string Status_name
{
get
{
return status_name;
}
set
{
status_name = value;
}
}
private string firstName;
public string FirstName
{
get
{
return firstName ;
}
set
{
firstName = value;
}
}
}
and use List<clients> for your method to map the result.
Edit: if your query is dynamic you can use the dynamic specifications of C#:
create a dynamic entity like this:
public class DynamicClass : DynamicObject
{
private IDictionary<string, object> _values;
public DynamicClass(IDictionary<string, object> values)
{
_values = values;
}
public override bool TryGetMember(GetMemberBinder binder, out object result)
{
if (_values.ContainsKey(binder.Name))
{
result = _values[binder.Name];
return true;
}
result = null;
return false;
}
}
you can build objects form the class like this:
var values = new Dictionary<string, object>();
values.Add("Username", "value which you read from database");
values.Add("Status_name", "value which you read from database");
values.Add("FirstName","value which you read from database" );
var client = new DynamicClass(values);
and then you can easily access the fields of this class like:
dynamic clientDyn= client ;
var username= clientDyn.Username;

get/set Accessors the correct scope

i created a class called ProfileHelper, and I can't seem to get my get/set accessors correct; instead, I'm getting red lines on both get and set. Here is the code I am trying to use:
public static String UserName(string columnName)
{
get
{
using (SqlConnection cn = new SqlConnection(SiteConfig.ConnectionString))
{
string sSql = ("SELECT UserName , LoweredUserName FROM aspnet_Users WHERE UserId = #UserId");
using (SqlCommand cm = new SqlCommand(sSql, cn))
{
cm.Parameters.AddWithValue("#UserId", Membership.GetUser().ProviderUserKey.ToString());
cn.Open();
using (SqlDataReader rd = cm.ExecuteReader())
{
while (rd.Read())
{
return columnName;
}
rd.Close();
}
cn.Close();
}
}
return columnName;
}
set
{
using (SqlConnection cn = new SqlConnection(SiteConfig.ConnectionString))
{
string sSql = ("UPDATE [aspnet_ Users] SET UserName = #UserName, LoweredUserName = #LoweredUserName WHERE UserId = #UserId");
using (SqlCommand cm = new SqlCommand(sSql, cn))
{
cm.Parameters.AddWithValue("#UserId", Membership.GetUser ().ProviderUserKey.ToString());
cn.Open();
cm.ExecuteNonQuery();
cn.Close();
}
}
}
}

That's a method, not a property. Only properties have get and set accessors. Pick one.
public static String UserName(string columnName) // this implies a method
{
get // this implies a property
{

Syntax is basically:
private string userName;
public string UserName // no parameter here!
{
get { return this.userName; }
set { this.userName = value; } // value is a keyword
}
Alternatively, auto-property do the backing field for you:
public string UserName { get; set; } // equivalent
public string MyExternallyReadOnly { get; private set; } // setter is private
You should not fiddle around with SQL connections in properties. Access to properties should be fast and reliable. Consider replacing it by methods to make it clear that this is actually a longer-enduring action with external dependencies (which is more likely to fail):
public string GetUserName() { }
public void UpdateUserName() {}

You should make a pair of methods, GetUserName(string columnName) and SetUserName(string columnName, string value). This is the preferred approach when it will probably take a while, e.g. because you're making a DB connection, and lets you easily have a parameter.
public static String UserName(string columnName) is the signature for a method. public static String UserName would be a property. Properties have get/set accessors, methods do not. You need to change this. Properties do not allow arguments, except for indexed properties, which can't be static (e.g. used like myObj[someColumnName], declared like public string this[string columnName]). If you're expecting to access the property like var something = ProfileHelper.UserName;, just use a property.