Most efficient try/finally/dispose

Question

I have this method where I may pass a DbContext or I may not:

public static List<ClaimService> GetServicesForAccountType(DatabaseContainer db,Guid claimId, Guid accountTypeId)
{
    bool dispose = (db == null ? true :false);
    try
    {
        db = (db ==  null ?  new DatabaseContainer(): db);
        return db.Database.SqlQuery<ClaimService>("SELECT * FROM dbo.ClaimService WHERE ClaimId = '@p1' AND AccountTypeId = '@p2'", new System.Data.SqlClient.SqlParameter("p1", claimId), new System.Data.SqlClient.SqlParameter("p2", accountTypeId)).ToList();
    }
    finally
    {
        if (dispose) { db.Dispose(); }
    }
}

I am doing 2 ternary operations, 1 to determine if I should do a dispose and another to determine if I need to create a new dbContext.

Question: Both ternary ops are the exact same condition (db == null), is there a way I can set my dispose and my db variables in one op?

Answer 1

Your first statement can be rewritten as

bool dispose = db == null;

and the second as

db = db ?? new DatabaseContainer();

See the null-coalescing operator for this last option.

Answer 2

You can use dispose in second check:

db = (dispose ?  new DatabaseContainer() : db);

or use null-coalescing operator:

db = db ?? new DatabaseContainer();

Answer 3

Sounds like you want to dispose db if you were responsible for creating it, but use the one passed and do not dispose if not. You could do something like:

public static List<ClaimService> GetServicesForAccountType(DatabaseContainer db,Guid claimId, Guid accountTypeId)
{
    DatabaseContaner localScopeDbContainer = null;

    try
    {
        db = db ?? (localScopeDbContainer = new DatabaseContainer());
        return db.Database.SqlQuery<ClaimService>("SELECT * FROM dbo.ClaimService WHERE ClaimId = '@p1' AND AccountTypeId = '@p2'", new System.Data.SqlClient.SqlParameter("p1", claimId), new System.Data.SqlClient.SqlParameter("p2", accountTypeId)).ToList();
    }
    finally
    {
        if (localScopeDbContainer != null)
            localScopeDbContainer.Dispose();
    }
}

You could even skip the db = and do a one-liner:

public static List<ClaimService> GetServicesForAccountType(DatabaseContainer db,Guid claimId, Guid accountTypeId)
{
    DatabaseContaner localScopeDbContainer = null;

    try
    {
        return (db ?? (localScopeDbContainer = new DatabaseContainer()).Database.SqlQuery<ClaimService>("SELECT * FROM dbo.ClaimService WHERE ClaimId = '@p1' AND AccountTypeId = '@p2'", new System.Data.SqlClient.SqlParameter("p1", claimId), new System.Data.SqlClient.SqlParameter("p2", accountTypeId)).ToList();
    }
    finally
    {
        if (localScopeDbContainer != null)
            localScopeDbContainer.Dispose();
    }
}

But I'm not sure how much readability any of this gets you.