Not all code paths return a value

Hi there,

To start off with please forgive me if this is not in the right place!

So, I've devised a simple ID checker whose only conditions to return true are that it is a certain length, and currently exists in my database. For some reason, It claims not all code paths return a value even though they do as far as I can tell? I'm using SQLite for reference.

Many thanks in advance.

Code (CSharp):

1. private bool PlayerIDChecker(string id)
2. {
3.     if (id.Length < 3 || id.Length > 16)
4.     {
5.         return false;
6.     }
7.  
8.     // Next check requires Initialising file path to DB
9.     connectDB = "URI=file:" + Application.dataPath + "/HighScoreDB.db";
10.  
11.     using (IDbConnection dbConnection = new SqliteConnection(connectDB))
12.     {
13.         dbConnection.Open();
14.         using (IDbCommand dbCmd = dbConnection.CreateCommand())
15.         {
16.             // The EXISTS statement will return a 1 if the desired data exists, and a 0 if not
17.             sqlQuery = String.Format($"SELECT EXISTS (SELECT * FROM USERS WHERE PlayerID = '{id}')");
18.             dbCmd.CommandText = sqlQuery;
19.  
20.             string exists = dbCmd.ExecuteScalar().ToString();
21.  
22.             // Record exists
23.             if (exists == "1")
24.             {
25.                 return true;
26.             }
27.             // Record doesn't exist
28.             else if (exists == "0")
29.             {
30.                 return false;
31.             }
32.         }
33.         dbConnection.Close();
34.      
35.     }
36.  
37. }

 

So.... what value does this method return once it executes dbConnection.Close() on line 33?

 

Your return values are inside using blocks, and you have code that needs to run outside of those blocks.
If this would run, you would never actually close the database connection on line 33, because it would never reach that point.

Personally, I like using the "only one return statement" approach to writing methods. I find it easier to debug and it guarantees that all code paths can run.

Code (CSharp):

1. private bool PlayerIDChecker(string id)
2. {
3.     bool result = !(id.Length < 3 || id.Length > 16);
4.  
5.     if(!result) {
6.         // Next check requires Initialising file path to DB
7.         connectDB = "URI=file:" + Application.dataPath + "/HighScoreDB.db";
8.  
9.         using (IDbConnection dbConnection = new SqliteConnection(connectDB))
10.         {
11.             dbConnection.Open();
12.             using (IDbCommand dbCmd = dbConnection.CreateCommand())
13.             {
14.                 // The EXISTS statement will return a 1 if the desired data exists, and a 0 if not
15.                 sqlQuery = String.Format($"SELECT EXISTS (SELECT * FROM USERS WHERE PlayerID = '{id}')");
16.                 dbCmd.CommandText = sqlQuery;
17.  
18.                 string exists = dbCmd.ExecuteScalar().ToString();
19.                 result = exists == "1";
20.             }
21.             dbConnection.Close();
22.         }
23.     }
24.  
25.     return result;
26. }

 

Ah I see! Thanks for your help