C#•15mo 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•15mo ago

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

Richard Evanson•15mo ago

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

gondeman•15mo 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

Richard Evanson•15mo ago

use this when I call the method?

gondeman•15mo ago

yes

HimmDawg•15mo ago

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

Cattywampus•15mo ago

assing null to it?

HimmDawg•15mo ago

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

Richard Evanson•15mo ago

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

HimmDawg•15mo ago

Return a nullable MySqlConnection then

Richard Evanson•15mo 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•15mo ago

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

Richard Evanson•15mo 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•15mo 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?

Richard Evanson•15mo 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•15mo 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•15mo 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.

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❔ can I make variable nullable withouse initializing it?