Develop Reference

Generic class method using SQLite-Net

I am trying to write a generic method to get the data from tables.
I am using sqlite-net ORM.
My methods compile well for delete:
public bool DeleteItem<T>(T NewItem)
{
SQLiteConnection conn = new SQLiteConnection(GetConnection());
var result = conn.Delete<T>(NewItem);
//...
}
And
public void CreateTable<T>()
{
SQLiteConnection conn = new SQLiteConnection(GetConnection());
conn.CreateTable<T>();
conn.Close();
}
But if I try to get Table data as list, I get a compile error at conn.Table:
T Must be a non-Abstract Type ....
Here is my code that does not want to compile:
public List<T> GetAllItems<T>(string SelTable)
{
SQLiteConnection conn = new SQLiteConnection(GetConnection());
List<T> MyItems = conn.Table<T>().ToList();
conn.Close();
return MyItems;
}

The definition of Table in SQLiteConnection is
public TableQuery<T> Table<T>() where T : new();
So you have to add type constraints:
public bool DeleteItem<T>(T NewItem) where T : new() // not required, but useful
{
SQLiteConnection conn = new SQLiteConnection("xx");
var result = conn.Delete<T>(NewItem);
return true;
}
public void CreateTable<T>() where T : new() // not required, but useful
{
SQLiteConnection conn = new SQLiteConnection("xx");
conn.CreateTable<T>();
conn.Close();
}
public List<T> GetAllItems<T>(string SelTable) where T : new()
{
SQLiteConnection conn = new SQLiteConnection("xx");
List<T> MyItems = conn.Table<T>().ToList();
conn.Close();
return MyItems;
}

How to separate the Data Access Layer into smaller classes

I have a design problem with a 3 Tier application. Usually my database layer is only 1 class like this one:
public class DA
{
string _connString = "";
public DA()
{
_connString = ConfigurationManager.ConnectionStrings["MyConnString"].ToString();
}
public DA(string connString)
{
_connString = connString;
}
private SqlConnection GetConnection()
{
...
}
public Employee GetEmployee(int idEmployee)
{
...
}
public Whatever GetWhatever(int idWhatever)
{
...
}
...
But now I have a pretty big project and I would like to separate the DA class into smaller classes like DA_Employee, DA_Whatever, etc.
I would like to instantiate only DA one time and access the other classes like that:
DA db = new DA(connString);
db.Employee.GetEmployee(12);
db.Whatever.GetWhatever(89);
db.Whatever.UpdateWhatever(89, "newname");
I would prefer NOT having something like this:
DA db = new DA(connString);
DA_Employee dbEmployee = new DA_Employee(connString);
DA_Whatever dbWhataver = new DA_Whatever(connString);
I think I can instantiate all my classes in my main constructor and have some properties to access them?
How can I give access to all classes to GetConnection()?
Any help and reference appreciated.
Thanks!

Yes, you make the classes a property of DA.
public interface IRepository<T>
{
T GetById(int id);
}
public class EmployeeRepository : IRepository<Employee>
{
private SqlConnection sqlConn;
public EmployeeRepository(SqlConnection sqlconn)
{
this.sqlConn = sqlConn;
}
public Employee GetById(int id)
{
return new Employee();
}
}
Pass the SqlConnection as a constructor dependency.
public class DA : IDisposable
{
private SqlConnection sqlConn;
private IRepository<Employee> employeeRepo;
private IReposiotry<Whatever> whateverRepo;
public DA(string connectionString)
{
this.sqlConnection = GetSqlConnection(connectionString);
this.employeeRepo = new EmployeeRepository(this.sqlConnection);
this.whateverRepo = new WhateverRepository(this.sqlConnection);
}
public IRepository<Employee> Employee { get { return employeeRepo; } }
public IRepository<Whatever> Whatever { get { return whateverRepo; } }
}
And its usage
using (var db = new DA("connectionString"))
{
db.Employee.GetById(1);
db.Whatever.GetById(10);
}

C#: How to Wrap my Unit of Work code in my repository classes

See my repository code
public abstract class AdoRepository<T> where T : class
{
private static SqlConnection _connection;
public AdoRepository(string connectionString)
{
_connection = new SqlConnection(connectionString);
}
public virtual T PopulateRecord(SqlDataReader reader)
{
return null;
}
public virtual void GetDataCount(int count)
{
}
protected IEnumerable<T> GetRecords(SqlCommand command)
{
var list = new List<T>();
command.Connection = _connection;
_connection.Open();
try
{
var reader = command.ExecuteReader();
try
{
while (reader.Read())
{
list.Add(PopulateRecord(reader));
}
reader.NextResult();
if (reader.HasRows)
{
while (reader.Read())
{
GetDataCount(Convert.ToInt32(reader["Count"].ToString()));
}
}
}
finally
{
// Always call Close when done reading.
reader.Close();
}
}
catch(Exception ex)
{
string Msg = ex.Message;
}
finally
{
_connection.Close();
}
return list;
}
protected T GetRecord(SqlCommand command)
{
T record = null;
command.Connection = _connection;
_connection.Open();
try
{
var reader = command.ExecuteReader();
try
{
while (reader.Read())
{
record = PopulateRecord(reader);
break;
}
}
finally
{
// Always call Close when done reading.
reader.Close();
}
}
finally
{
_connection.Close();
}
return record;
}
protected IEnumerable<T> ExecuteStoredProc(SqlCommand command)
{
var list = new List<T>();
command.Connection = _connection;
command.CommandType = CommandType.StoredProcedure;
_connection.Open();
try
{
var reader = command.ExecuteReader();
try
{
while (reader.Read())
{
var record = PopulateRecord(reader);
if (record != null) list.Add(record);
}
}
finally
{
// Always call Close when done reading.
reader.Close();
}
}
finally
{
_connection.Close();
}
return list;
}
}
public class StudentRepository : AdoRepository<Student>
{
public int DataCounter { get; set; }
public StudentRepository(string connectionString)
: base(connectionString)
{
}
public IEnumerable<Student> GetAll()
{
// DBAs across the country are having strokes
// over this next command!
using (var command = new SqlCommand("SELECT ID, FirstName,LastName,IsActive,StateName,CityName FROM vwListStudents"))
{
return GetRecords(command);
}
}
public Student GetById(string id)
{
// PARAMETERIZED QUERIES!
using (var command = new SqlCommand("SELECT ID, FirstName,LastName,IsActive,StateName,CityName FROM vwListStudents WHERE Id = #id"))
{
command.Parameters.Add(new ObjectParameter("id", id));
return GetRecord(command);
}
}
public IEnumerable<Student> GetStudents(int StartIndex, int EndIndex, string sortCol, string sortOrder)
{
string strSQL = "SELECT * FROM vwListStudents WHERE ID >=" + StartIndex + " AND ID <=" + EndIndex;
strSQL += " ORDER BY " + sortCol + " " + sortOrder;
strSQL += ";SELECT COUNT(*) AS Count FROM vwListStudents";
var command = new SqlCommand(strSQL);
return GetRecords(command);
}
public override Student PopulateRecord(SqlDataReader reader)
{
return new Student
{
ID = Convert.ToInt32(reader["ID"].ToString()),
FirstName = reader["FirstName"].ToString(),
LastName = reader["LastName"].ToString(),
IsActive = Convert.ToBoolean(reader["IsActive"]),
StateName = reader["StateName"].ToString(),
CityName = reader["CityName"].ToString()
};
}
public override void GetDataCount(int count)
{
DataCounter = count;
}
}
this way unit of work code added
public class UnitOfWorkFactory
{
public static IUnitOfWork Create()
{
var connection = new SqlConnection(ConfigurationManager.ConnectionStrings("MyDb").ConnectionString);
connection.Open();
return new AdoNetUnitOfWork(connection, true);
}
}
public class AdoNetUnitOfWork : IUnitOfWork
{
public AdoNetUnitOfWork(IDbConnection connection, bool ownsConnection)
{
_connection = connection;
_ownsConnection=ownsConnection;
_transaction = connection.BeginTransaction();
}
public IDbCommand CreateCommand()
{
var command = _connection.CreateCommand();
command.Transaction = _transaction;
return command;
}
public void SaveChanges()
{
if (_transaction == null)
throw new InvalidOperationException("Transaction have already been commited. Check your transaction handling.");
_transaction.Commit();
_transaction = null;
}
public void Dispose()
{
if (_transaction != null)
{
_transaction.Rollback();
_transaction = null;
}
if (_connection != null && _ownsConnection)
{
_connection.Close();
_connection = null;
}
}
}
using (var uow = UnitOfWorkFactory.Create())
{
var repos = new UserRepository(uow);
uow.SaveChanges();
}
public class UserRepository
{
private AdoNetUnitOfWork _unitOfWork;
public UserRepository(IUnitOfWork uow)
{
if (uow == null)
throw new ArgumentNullException("uow");
_unitOfWork = uow as AdoNetUnitOfWork;
if (_unitOfWork == null)
throw new NotSupportedException("Ohh my, change that UnitOfWorkFactory, will you?");
}
public User Get(Guid id)
{
using (var cmd = _unitOfWork.CreateCommand())
{
cmd.CommandText = "SELECT * FROM Users WHERE Id = #id");
cmd.AddParameter("id", id);
// uses an extension method which I will demonstrate in a
// blog post in a couple of days
return cmd.FirstOrDefault<User>();
}
}
}
but i want to add unit of work code in my repository class. may be in AdoRepository class or StudentRepository class as a result i do not have to write the below code again and again.
using (var uow = UnitOfWorkFactory.Create())
{
var repos = new UserRepository(uow);
uow.SaveChanges();
}
so when i will be working with any repository like UserRepository then i have to repeat again and again this lines of code UnitOfWorkFactory.Create() which i do not want rather i am looking for a way to embed unit of work code in some where centralize as a result i could reduce the repeated code.
so looking for idea and suggestion. if possible give me modified version of code.
thanks

I will be straightforward about this:
A UoW that contains repositories is an anti pattern at least if DDD is involved. If it isn't, then you're dealing with a very simple app so make you life easier and use a ORM which implements what you want.
As a thumb rule, a repository may contain a UoW as an implementation detail and you should be certain that you really need a repository. A repository inside a UoW is a very specific case which is valid ONLY with CRUD apps and you'll just be reinventing a very small part of an ORM.
Using ado.net directly is wasting time (and money). Either use an ORM or a data mapper aka micro-ORM. With the latter option the UoW is the Db transaction.
You don't gain anything significant using Ado.Net,the performance gain is so small it's not even funny (I know that because I've benchmarked it). The only thing you'll get is longer devel time and human errors.
Actually, if I take a better look at your code, you're basically building a micro ORM, without knowing it. It's still not a repository though, because the abstraction doesn't have business semantics and it's too tightly coupled to an implementation detail.

Cannot implicitly convert type 'void' to 'string'

I've tried for a while now and I really dont get it. I recive error "Cannot implicitly convert type 'void' to 'string'"
I have tried multiple variants of string, int, nothing, void, public, static and nope I really dont get it right.
I want to get one value from my db thoug my DAL and BLL, my code looks like this.
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
Repeater1.DataSource = BLL.getGames();
Repeater1.DataBind();
var culture = CultureInfo.GetCultureInfo("sv-SE");
var dateTimeInfo = DateTimeFormatInfo.GetInstance(culture);
var dateTime = DateTime.Today;
int weekNumber = culture.Calendar.GetWeekOfYear(dateTime, dateTimeInfo.CalendarWeekRule, dateTimeInfo.FirstDayOfWeek);
string mroundY = dateTime.Year.ToString();
string mroundW = weekNumber.ToString();
string mrounddate = mroundY + mroundW;
string mround = BLL.getMroundGames(mrounddate); <-- Here's the error
}
protected void Repeater1_ItemCommand(object source, RepeaterCommandEventArgs e)
{
}
}
My BLL looks like this;
public class BLL
{
public static void getMroundGames(string mrounddate)
{
SqlCommand getMroundGames = new SqlCommand("SELECT mround FROM gameTB where mround = #mrounddate");
DAL.ExecuteNonQuery(getMroundGames);
}
}
Also tried this;
public class BLL
{
public static DataTable getMroundGames(string mrounddate)
{
SqlCommand getMroundGames = new SqlCommand("SELECT mround FROM gameTB where mround = #mrounddate");
getMroundGames.Parameters.Add("#mrounddate", SqlDbType.VarChar, 10).Value = mrounddate;
return DAL.GetData(getMroundGames);
}
}
And finaly my DAL looks like this;
public class DAL
{
public static SqlConnection GetConnection()
{
SqlConnection conn = new
SqlConnection(ConfigurationManager.ConnectionStrings["tiptopConnectionString"].ConnectionString);
conn.Open();
return conn;
}
public static DataTable GetData(SqlCommand command)
{
try
{
using (SqlConnection conn = GetConnection())
{
using (DataSet ds = new DataSet())
{
using (SqlDataAdapter da = new SqlDataAdapter())
{
da.SelectCommand = command;
da.SelectCommand.Connection = conn;
da.Fill(ds);
return ds.Tables[0];
}
}
}
}
catch (Exception err)
{
throw new ApplicationException(string.Format("Felmeddelande:{0}", err.Message));
}
}
public static object ExecuteScalar(SqlCommand command)
{
using (SqlConnection conn = GetConnection())
{
command.Connection = conn;
object result = command.ExecuteScalar();
return result;
}
}
public static void ExecuteNonQuery(SqlCommand command)
{
using (SqlConnection conn = GetConnection())
{
command.Connection = conn;
command.ExecuteNonQuery();
}
}
}
Where to begin?

The signature for this is wrong;
public static void getMroundGames(string mrounddate)
You need to change it to something similar to ;
public static string getMroundGames(string mrounddate)
Retrieve the string value from your DAL and return to the consumer accordingly.
var dt = Dal.GetData();
return (string)dt.Rows[0]["field"];
However, in all honesty, I would not be passing a datatable from your DAL to your BLL. I would return the string directly or introduce a DTO and populate this from your DAL through your BLL, back to the consumer.

You need to add a return type of string to getMroundGameas(string mrounddate).
It's not clear what type of object DAL is, but you should also probably use ExecuteReader method, http://msdn.microsoft.com/en-us/library/bb344397.aspx
rather then ExecuteNonQuery. This will return a Reader which can be queried for the value returned by the select statement.
Finally you should return the value.

How to mock SqlParameterCollection using Moq

I am trying to mock database operations. I have problem in mocking SqlParameterCollection. I tried to create virtual method that will return DbParameterCollection but then i am loosing all the functionality that SqlParameterCollection gives like AddWithValue etc. Is there a way i can mock SqlParameterCollection? Is there any other approach to unit test DAL? I am using Moq.
Code goes like this:
in DAL:
protected virtual IDbConnection GetConnection(string connectionString)
{
return new SqlConnection(connectionString);
}
protected virtual IDbCommand GetCommand(IDbConnection cn)
{
return cn.CreateCommand();
}
protected virtual IDbTransaction GetTransaction(IDbConnection cn)
{
return cn.BeginTransaction(IsolationLevel.Serializable);
}
Public Bool InsertInDatabase(DataTable dt)
{
using (IDbConnection cn = GetConnection(cnstr))
{
cn.Open();
using (IDbTransaction tran = GetTransaction(cn))
{
IDbCommand cmd = GetCommand(cn);
cmd.Transaction = tran;
cmd.Connection = cn;
cmd.CommandType = CommandType.StoredProcedure;
cmd.CommandText = "sp_InsertInDatabase";
SqlParameterCollection cmdParams = cmd.Parameters as SqlParameterCollection;
cmdParams.AddWithValue("#param1", dt);
cmd.ExecuteNonQuery();
}
}
}
In Unit test project:
protected override IDbConnection GetConnection(string connectionString)
{
return Mock.Of<IDbConnection>();
}
protected override IDbCommand GetCommand(IDbConnection cn)
{
return Mock.Of<IDbCommand>();
}
protected override IDbTransaction GetTransaction(IDbConnection cn)
{
return Mock.Of<IDbTransaction>();
}
public void TestInsertInDatabase()
{
base.InsertInDatabase(new DataTable());
}
--Solution--
Created an extension method to add parameter with value. Thank you Marc Gravell for pointing me to that direction.
public static IDbDataParameter AddParameterWithValue(this IDbCommand cmd, string paramName, object paramValue)
{
var dbParam = cmd.CreateParameter();
if (dbParam != null)
{
dbParam.ParameterName = paramName;
dbParam.Value = paramValue;
}
return dbParam;
}

Personally, I approach this problem by writing an AddParameterWithValue extension method to DbCommand (or IDbCommand). It has to be on the command so that you have access to CreateParameter, and then call .Parameters.Add.
This allows easy usage against any ADO.NET stack, including abstractions like logging decorators.

#Asdfg HI I have basically mocked the parameter collection as below
string connectionString = "connectionstring";
var sqlConnection = new SqlConnection(connectionString);
var command = sqlConnection.CreateCommand();
//****************Setup Mock************************//
Castle.DynamicProxy.Generators.AttributesToAvoidReplicating.Add(typeof(System.Data.SqlClient.SqlClientPermissionAttribute));
var mockDataReader1 = new Mock<IDataReader>();
command.Parameters.Add(new SqlParameter("#po_tint_Result", 1));
//setup read return value
Queue<bool> responseQueue = new Queue<bool>();
responseQueue.Enqueue(true);
responseQueue.Enqueue(false);
mockDataReader1.Setup(a => a.Read()).Returns(() => responseQueue.Dequeue());
var mockDb = new Mock<SqlDatabase>(connectionString);
mockDb.Setup(a => a.GetStoredProcCommand("SPNAME")).Returns(command);
mockDb.Setup(a => a.ExecuteNonQuery(command));
obj1.DbConn = mockDb.Object;
//*************************************************//
Hope this helps

Hi i found the solution.
I had to implement a Moq for the IDataParameterCollection interface and had to send it to the instance of IDbCommand.
With that my IDbCommand.Parameters object became different from null.
public static IDbConnection IDbConnectionMock(int valReturn)
{
var dataParameterCollection = new Mock<IDataParameterCollection>();
var command = new Mock<IDbCommand>();
command.Setup(x => x.Parameters).Returns(dataParameterCollection.Object);
command.Setup(x => x.ExecuteNonQuery()).Returns(valReturn);
var connection = DbConnectionMock_Success(command.Object);
return connection;
}