在SQLite数据库中保存接口项列表

Question

I'm developing an app at the moment. To save the items I want to use an SQLite database. The implementation works in general (using the SQLite.Net-PCL library), however I'm failing at saving a collection of items that inherit from a interface called IItem .

It works the following way:

var conn = new SQLiteConnection(new SQLitePlatformWinRT(), "myapp.db");

// Code that creates the `items` list.

foreach (IItem item in items)
    conn.InsertOrReplace(item, typeof(IItem));

But to reduce the overhead, I prefer it to do it this way:

conn.InsertOrReplaceAll(items, typeof(List<IItem>));

Sadly this doesn't work due to an System.Reflection.TargetException .

Any ideas to get the latter one working, primary because of perf reasons?

Answer 1

The problem here is that you are using wrong type as the parameter in InsertOrReplaceAll method. The objType in this method represents the type of the single item , you can use this method like following:

conn.InsertOrReplaceAll(items, typeof(IItem));

To see this clearly, we can look at the source code on GitHub :

public int InsertOrReplaceAll(IEnumerable objects, Type objType)
{
    var c = 0;
    RunInTransaction(() =>
    {
        foreach (var r in objects)
        {
            c += InsertOrReplace(r, objType);
        }
    });
    return c;
}

From the source code, we can find in this method, it also calls InsertOrReplace(object obj, Type objType) method. Besides, there is another overload method of InsertOrReplaceAll .

public int InsertOrReplaceAll(IEnumerable objects);

With this method, we can do not care about the type issue.