Develop Reference

Adding/Removing SQLite database password programmatically

Trying to create functions to programmatically add a password to the sqlite database, and remove it - to get rid of the password when in debug.
I followed the steps of the best post explaining it (https://stackoverflow.com/a/1385690/6617804) and all the other sources that I found are using the same process.
What I am doing:
The connection strings:
private static string AuthoringDbFullPath = System.IO.Path.Combine(DataFolder, "Authoring.db");
private static string AuthoringConnectionStringWithPw = #"Data Source=" + AuthoringDbFullPath + "; Password=" + DbPassword +";";
private static string AuthoringConnectionStringWithoutPw = #"Data Source=" + AuthoringDbFullPath+";";
private static string AuthoringConnectionString = AuthoringConnectionStringWithPw;
The enable password function:
public static bool EnableDbPassword()
{
try
{
//The Connection must not open closed to set a password
Connection = new SQLiteConnection(AuthoringConnectionStringWithoutPw);
Connection.SetPassword(DbPassword);
Connection = new SQLiteConnection(AuthoringConnectionStringWithPw);
Connection.Open();
Connection.Close();
if (Connection != null && Connection?.State == System.Data.ConnectionState.Open)
{
Connection.SetPassword(DbPassword);
AuthoringConnectionString = AuthoringConnectionStringWithPw;
return true;
}
}
catch (Exception ex)
{
LogManager.LogException(ex);
}
return false;
}
The disable password function:
public static bool DisableDbPassword()
{
try
{
//if not connected, it does
if (Connection == null || Connection?.State != System.Data.ConnectionState.Open)
{
Connection = new SQLiteConnection(AuthoringConnectionStringWithPw);
Connection.Open();
}
Connection.Close();
Connection.Open();
if (Connection != null && Connection?.State == System.Data.ConnectionState.Open)
{
Connection.ChangePassword("");
AuthoringConnectionString = AuthoringConnectionStringWithoutPw;
return true;
}
}
catch (Exception ex)
{
LogManager.LogException(ex);
}
return false;
}
Two things happening:
After having add the password (with no apparent issue), I can still open the database in SQLiteStudio as if there were still no password:
When trying to disable after having enabled it, it raised a System.Data.SQLite.SqliteException exception when executing Connection.ChangePassword("");
System.Data.SQLite.SqliteException :
Message "file is not a database. not an error
How to create a simple architecture being able to add and remove a password on a SQLite database?

Exception handling quandry

I am throwing a new exception when a database row is not found.
Class that was called:
public ProfileBO retrieveProfileByCode(string profileCode)
{
return retrieveSingleProfile("profile_code", profileCode);
}
private ProfileBO retrieveSingleProfile(string termField, string termValue)
{
ProfileBO profile = new ProfileBO();
//Query string is temporary. Will make this a stored procedure.
string queryString = " SELECT * FROM GamePresenterDB.gp.Profile WHERE " + termField + " = '" + termValue + "'";
using (SqlConnection connection = new SqlConnection(App.getConnectionString()))
{
connection.Open();
SqlCommand command = new SqlCommand(queryString, connection);
SqlDataReader reader = command.ExecuteReader();
if (reader.Read())
{
profile = castDataReadertoProfileBO(reader, profile);
}
else
{
// No record was selected. log it and throw the exception (We'll log it later, for now just write to console.)
Console.WriteLine("No record was selected from the database for method retrieveSingleProfile()");
throw new InvalidOperationException("An exception occured. No data was found while trying to retrienve a single profile.");
}
reader.Close();
}
return profile;
}
However, when I catch the exception in the calling class, 'e' is now null. What am I doing wrong? I believe this works fine in Java, so C# must handle this differently.
Calling class:
private void loadActiveProfile()
{
try
{
ProfileBO profile = profileDAO.retrieveProfileByCode(p.activeProfileCode);
txtActiveProfileName.Text = profile.profile_name;
}
catch (InvalidOperationException e)
{
}
}

Now all the code has been put in the question, you can move the try catch outside of your 'loadActiveProfile' method and place it into 'retrieveSingleProfile'.
private void loadActiveProfile()
{
ProfileBO profile = profileDAO.retrieveProfileByCode(p.activeProfileCode);
txtActiveProfileName.Text = profile.profile_name;
}
removed the try catch^
private ProfileBO retrieveSingleProfile(string termField, string termValue)
{
try {
ProfileBO profile = new ProfileBO();
//Query string is temporary. Will make this a stored procedure.
string queryString = " SELECT * FROM GamePresenterDB.gp.Profile WHERE " + termField + " = '" + termValue + "'";
using (SqlConnection connection = new SqlConnection(App.getConnectionString()))
{
connection.Open();
SqlCommand command = new SqlCommand(queryString, connection);
SqlDataReader reader = command.ExecuteReader();
if (reader.Read())
{
profile = castDataReadertoProfileBO(reader, profile);
}
else
{
// No record was selected. log it and throw the exception (We'll log it later, for now just write to console.)
Console.WriteLine("No record was selected from the database for method retrieveSingleProfile()");
throw new InvalidOperationException("An exception occured. No data was found while trying to retrienve a single profile.");
}
reader.Close();
}
return profile;
}
catch(InvalidOperationException e)
{
}
}
Added try catch in the correct place.

You need to step into the catch block for e to be set to the thrown InvalidOperationException:
catch (System.InvalidOperationException e)
{
int breakPoint = 0; //<- set a breakpoint here.
//Either you reach the breakpoint and have an InvalidOperationException, or you don't reach the breakpoint.
MessageBox.Show(e.Message);
}
Also make sure that the InvalidOperationException you throw is actually a System.InvalidOperationException and not some custom type of yours called "InvalidOperationException".

Like #Clemens said, you need to show all the relevant code.
As a quick test, this works just fine:
class Program
{
static void Main(string[] args)
{
try
{
Console.WriteLine("Throwing error");
ThrowException();
}
catch (InvalidOperationException e)
{
Console.WriteLine(e.Message);
}
Console.ReadKey(true);
}
static void ThrowException()
{
throw new InvalidOperationException("Blah blah blah");
}
}

Transactionscope rollback

I have a method inside a main one. I need the child method to be able to roll back if the parent method fails. The two data connections use different servers . Before I added the transaction scopes, they worked well. But when I tie them together, the child method aborts.
Edit: Error message: Network access for distributed transaction Manager(MSDTC) has been disabled. Please enable DTC for network access in the security configuration for MSDTC using Component Service Administrative tool.
public static void LoopStudent()
{
try
{
using(TransactionScope scope = new TransactionScope())
{
String connString = ConfigurationManager.AppSettings["DBConnection"];
using(SqlConnection webConn = new SqlConnection(connString))
{
webConn.Open();
String sql = "select * from students";
using(SqlCommand webComm = new SqlCommand(sql, webConn))
{
using(SqlDataReader webReader = webComm.ExecuteReader())
{
if (webReader.HasRows)
{
while (webReader.Read())
{
int i = GetNextId();
}
}
else
Console.WriteLine("wrong");
}
}
}
scope.Complete();
}
}
catch (Exception ex)
{
Console.WriteLine("Error " + ex.Message);
}
} //End LoopThroughCart
public static int GetNextId(String str)
{
int nextId = 0;
String connString = ConfigurationManager.AppSettings["SecondDBConnection"];
try
{
using(TransactionScope scope = new TransactionScope())
{
using(SqlConnection webConn = new SqlConnection(connString))
{
webConn.Open();
using(SqlCommand webComm = new SqlCommand("GetNextId", webConn))
{
//do things
}
}
scope.Complete();
}
}
catch (TransactionAbortedException ex)
{
Console.WriteLine("TransactionAbortedException Message: {0}", ex.Message);
}
catch (ApplicationException ex)
{
Console.WriteLine("ApplicationException Message: {0}", ex.Message);
}
return nextId;
} //End GetNextId

If you do not use RequireNew in you inner method, the inner method will be automatically rolled back if the parent fails to commit the transaction.
What error are you getting?

Error happened while connection to oracle via c#

I have a windows application that write with c# 4. in this windows application i get user name, password, server IP and etc from user and create a oracle connection string from this inputs and test connect to database by this code:
private OperationStatus CheckConnectToOracleDatabase(string connectionString)
{
var oracleConnection = new OracleConnection();
try
{
oracleConnection.ConnectionString = connectionString;
oracleConnection.Open();
oracleConnection.Close();
return new OperationStatus { Status = true };
}
catch (OracleException ex)
{
return new OperationStatus { Status = false, ExceptionMessage = ex.Message };
}
catch (Exception ex)
{
return new OperationStatus { Status = false, ExceptionMessage = ex.Message };
}
finally
{
if (oracleConnection.State != ConnectionState.Closed)
oracleConnection.Close();
}
}
In my platform everything is OK and test is successful, but in the platform of customer and error was happened, this error was shown in below picture:
my platform is win server 2003, and platform of customer is win 7 32bit.

Add a new User for the database in mongodb

I want to add a new user to newly created database and if this user exists then i will connect to that database.
My code is:
public CreateDatabaseOperationResult CreateDatabase(string databaseName,string username,string password, MongoServer server)
{
CreateDatabaseOperationResult createDatabaseOpResult = new CreateDatabaseOperationResult();
string message = null;
MongoCredentials credentials = new MongoCredentials(username, password);
MongoUser user = new MongoUser(credentials, false);
try
{
if (IsDatabaseNameValid(databaseName, out message))
{
if (server.DatabaseExists(databaseName, admincredentials) == true)
{
createDatabaseOpResult.Database = server.GetDatabase(databaseName, credentials);
MongoUser tempuser = createDatabaseOpResult.Database.FindUser(username);
if (tempuser.Equals(user))
{
//createDatabaseOpResult.DatabaseExists = true;
createDatabaseOpResult.IsOperationSuccessfull = false;
throw new ArgumentException("Database Already exist with different set of credentials ");
}
}
else
{
createDatabaseOpResult.Database = server.GetDatabase(databaseName, credentials);
createDatabaseOpResult.Database.AddUser(user);
//createDatabaseOpResult.DatabaseExists = false;
}
createDatabaseOpResult.IsOperationSuccessfull = true;
}
}
catch (MongoQueryException ex)
{
createDatabaseOpResult.Error = ex;
}
//catch (MongoAuthenticationException ex)
//{
// createDatabaseOpResult.Error = ex;
//}
catch (MongoException ex)
{
createDatabaseOpResult.Error = ex;
}
catch (ArgumentException ex)
{
createDatabaseOpResult.Error = ex;
}
return createDatabaseOpResult;
}
When i use the existing database it connects to that database but when i try to add new use Database.AddUser gives error 'invalid credentials for this database'
Please see the error and reply

Most people use the mongo shell to add and remove users, but if you really want to do it in C# the trick is to use the right credentials depending on what you are trying to do. Assume you have the following two sets of credentials, one for the admin database and one for regular databases:
var adminCredentials = new MongoCredentials("myadminusername", "myadminpassword", true);
var userCredentials = new MongoCredentials("myusername", "myuserpassword");
Note that when creating the adminCredentials you must pass true to the admin parameter.
To test if a database exists requires admin credentials:
if (server.DatabaseExists("mydatabase", adminCredentials))
{
// database exists
}
To add a user requires admin credentials:
var myDatabaseWithAdminCredentials = server.GetDatabase("mydatabase", adminCredentials);
if (myDatabaseWithAdminCredentials.FindUser("myusername") == null)
{
myDatabaseWithAdminCredentials.AddUser(userCredentials);
}
Normally you use regular user credentials to work with a database:
var myDatabaseWithUserCredentials = server.GetDatabase("mydatabase", userCredentials);
var count = myDatabaseWithUserCredentials.GetCollection("mycollection").Count();
Also, keep in mind that each database can have any number of users, so you don't really need to be checking whether the database already exists with a different set of credentials.