c# - Xamarin.Android SQLite SQLiteConnection.Insert 不返回插入对象的 ID

Question

我是 Xamarin 和 C# 的新手，正在尝试将一些示例数据插入到我的简单配方数据库中以测试目的。

但是，当插入新配方时，SQLiteConnection.Insert(data) 不会返回插入记录的 ID(请参阅 here )，而是返回 1 每次。

我的插入数据方法:

public static int insertUpdate(Object data) {
        string path = DB.pathToDatabase ();
        DB.createDatabase ();
        try {
            var db = new SQLiteConnection(path);
            int inserted = db.Insert(data);
            if (inserted != 0)
                inserted = db.Update(data);
            return inserted;
        }
        catch (SQLiteException ex) {
            return -1;
        }
    }

插入示例数据:

        int stand = insertUpdate (new Recipe {
            Name = "Standard",
            Author = "Aeropress Nerd",
            Description = "The perfect recipe for your first cup",
            Type = "Default"
        });


        insertUpdate (new Step { Action = "Pour", Duration = 10, Recipe = stand });
        insertUpdate (new Step { Action = "Stir", Duration = 20, Recipe = stand });
        insertUpdate (new Step { Action = "Steep", Duration = 15, Recipe = stand });

        int inv = insertUpdate (new Recipe {
            Name = "Inverted",
            Author = "Aeropress Nerd",
            Description = "A more advanced brew using the inverted method.",
            Type = "Default"
        });

我不知道我做错了什么。在此先感谢您的帮助，并对这个(可能)愚蠢的问题表示抱歉。

Answer 1

However, when inserting a new recipe, the SQLiteConnection.Insert(data) does not return the ID of the inserted record as it should (see here), but instead returns 1 every time.

我很确定您下载了一些 nuget 包或组件以将 SQLite 功能包含到您的 Xamarin.Android 应用程序中，它可能与 native 实现略有不同。然后，无论您在 Xamarin 上使用什么，您都应该引用具体文档。

我的猜测是您正在使用 this component .如果我错了，请评论以更正我的答案。如果我是对的，你应该试试这个:

要插入的对象

class Row
{
   public int Id { get; set; }
}

class Recipe : Row
{
    //Recipe's properties
}

class Step : Row
{
    //Step's properties
}

insertUpdate 方法定义

public static int insertUpdate(Row data) {
    string path = DB.pathToDatabase ();
    DB.createDatabase ();
    try {
        var db = new SQLiteConnection(path);
        int inserted = db.Insert(data); //will be 1 if successful
        if (inserted > 0)
            return data.Id; //Acording to the documentation for the SQLIte component, the Insert method updates the id by reference
        return inserted;
    }
    catch (SQLiteException ex) {
        return -1;
    }
}

insertUpdate方法的使用

 //As Step and Recipe both are derived classed from Row, you should be able to use insertUpdate indistinctively and without casting

    insertUpdate (new Step { Action = "Steep", Duration = 15, Recipe = stand });

    int inv = insertUpdate (new Recipe {
        Name = "Inverted",
        Author = "Aeropress Nerd",
        Description = "A more advanced brew using the inverted method.",
        Type = "Default"
    });