C#•2y ago

❔ can I make variable nullable withouse initializing it?

I have this method that connect to database and I am checking if it connected:

        //Method connects to database
        public MySqlConnection ConnectDatabase()
        {
            MySqlConnection? connection;
            string config =
                "server = 127.0.0.1;" +
                "user = root;" +
                "database = trivia_bot_data";
            try
            {
                connection = new MySqlConnection(config);
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
                connection = null;
            }
            return connection;
        }

        //Method connects to database
        public MySqlConnection ConnectDatabase()
        {
            MySqlConnection? connection;
            string config =
                "server = 127.0.0.1;" +
                "user = root;" +
                "database = trivia_bot_data";
            try
            {
                connection = new MySqlConnection(config);
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
                connection = null;
            }
            return connection;
        }

17 Replies

gondeman•2y ago

yes its possible. Other way is to dispose the object.

Jack BadasssonOP•2y ago

well if I do it like this I just get same warning

gondeman•2y ago

I think it make more sense to use using. look at this code https://github.com/behdad088/GraphQL-API-Example/blob/main/GraphQLAPI/SQL.Database/DatabaseFactory.cs#L74

Jack BadasssonOP•2y ago

use this when I call the method?

gondeman•2y ago

yes

HimmDawg•2y ago

You cannot create a nullable variable and return the same variable as non-nullable

Cattywampus•2y ago

assing null to it?

HimmDawg•2y ago

I mean, you can But the compiler will warn you which is perfectly valid

Jack BadasssonOP•2y ago

I was told I need to eliminate all warnings it is bad to keep them

HimmDawg•2y ago

Return a nullable MySqlConnection then

Jack BadasssonOP•2y ago

I also want to ask if I have 4 classes where I will use database then I just need to connect database in each class with method like that? Is there no way to somehow connect database to whole program

HimmDawg•2y ago

Nay. Optimally you'd inject the database connection into the classes that need it

Jack BadasssonOP•2y ago

but what if I make class purely for working with database and create that class object for each class it would have connection to database as part of constructor

HimmDawg•2y ago

uh, i'm not sure if I can follow, but do you mean something like

class DatabaseClass
{
  ...
}

class ConsumerClass1
{
  public Foo GetFoo()
  {
    DatabaseClass dbClass = new();
  }
}

class DatabaseClass
{
  ...
}

class ConsumerClass1
{
  public Foo GetFoo()
  {
    DatabaseClass dbClass = new();
  }
}

Where DatabaseClass establishes the connection and where ConsumerClasses create the DatabaseClass?

Jack BadasssonOP•2y ago

yes but I would make dbclass as field or variable for whole cosummer class so I can call methods of it anywhere and initilize it together with consumer class I am not sure if it makes sense to do it I am gonna use database only a little

HimmDawg•2y ago

Yes, you'd rather inject the DatabaseClass into the ConsumerClasses then

I am gonna use database only a little

Depending on what is "a little" you can also think about injecting the result of what you are querying into the consumer classes. But it depends goblinnSip

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

Gaming

Programming

❔ can I make variable nullable withouse initializing it?