Make method that uses SQLiteConnection more reusable

user_13106354 0
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I am using sqlite-net in my project and have a helper class called SqLiteHelper. Inside this class I have a simple method that returns TableQuery results as a List. Example:

public static class SqLiteHelper
{
    public static List<Contact> GetTableQueryResults()
    {
        List<Contact> contacts;
        using (var connection = new SQLiteConnection(App.DatabasePath))
        {
            connection.CreateTable<Contact>();
            contacts = connection.Table<Contact>().ToList();
        }

        return contacts;
    }
}

I want to make this method reusable to use it in the future in other context. For example when I will have another project with a different class then 'Contact'. I tried it myself by refactoring it to this:

public static IList<T> GetTableQueryResults<T>()
{
    List<T> contacts;
    using (var connection = new SQLiteConnection(App.DatabasePath))
    {
        connection.CreateTable<T>();
        contacts = connection.Table<T>().ToList();
    }

    return contacts;
}

But the SQLiteConnection.Table<> method throws the following error:

Any ideas how I can make this method reusable?
I had a look here but it's not in connection with SQLite.

sqlite generics c#
1 Answers

Provide the generic type constraint of T as where T : new() in your method. The new() constraint lets the compiler know that any type argument supplied must have an accessible parameterless constructor.

Method:

public static IList<T> GetTableQueryResults<T>() where T : new()
{
    List<T> contacts;
    using (var connection = new SQLiteConnection(App.DatabasePath))
    {
        connection.CreateTable<T>();
        contacts = connection.Table<T>().ToList();
    }

    return contacts;
}

Read about new constraint at here.

user_16729940
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