Question

Xamarin和c＃的新手，但是我试图为我的班级制作一个非常简单的应用程序，在数据库中搜索成分并返回营养信息。我的小组知道python，所以他们写了代码，我试着制作一个简单的应用程序，因为我可以只是为了节目，但我有一些麻烦。我们从他们的网站下载了USDA数据库，并且该文件中的数据位于

＆＃34; NDB_No，Shrt_Desc，Energ_Kcal，Protein_g，Lipid_Tot_g，Ash_g，Carbohydrt_g，Fiber_TD_g，Sugar_Tot_g，Calcium_mg，Iron_mg，Magnesium_mg，Phosphorus_mg，Potassium_mg，Sodium_mg，Zinc_mg，Copper_mg，Manganese_mg，Selenium_ug，Vit_C_mg，Thiamin_mg，Riboflavin_mg ，Niacin_mg，Panto_Acid_mg，Vit_B6_mg，Folate_Tot_ug，Folic_Acid_ug，Food_Folate_ug，Folate_DFE_ug，Choline_Tot_毫克，Vit_B12_ug，Vit_A_IU，Vit_A_RAE，Retinol_ug，Alpha_Carot_ug，Beta_Carot_ug，Beta_Crypt_ug，Lycopene_ug，甩+ Zea_微克，Vit_E_mg，Vit_D_ug，Vit_D_IU，Vit_K_ug，FA_Sat_g，FA_Mono_g ，FA_Poly_g，Cholestrl_mg，Gm_unit，NUM，单元＆＃34;

具有数百种成分的格式。如

＆＃34; 1145，黄油，717,0.85,81.11,0.09,0.06,0,0.06,24,0.02,2,24,24,11,0.09,0.016,0.004,1,0,0.005,0.034 ，0.042,0.11,0.003,3,0,3,3,18.8,0.17,2499,684,671,0,158,0,0,0,2.32,0,0,7,50.489,23.43,3.01,215,5,1 ，汤匙＆＃34;

他们使用sqlite3创建一个表并在Python中查询它，只需使用c.fetchrow返回一行数据和一个数组来分割它。该代码可在此处找到：https://github.com/pjomara/SoftwareEngineeringIIProject/blob/master/nutr_data_grabber.py

我找不到任何好的例子，也不需要创建数据库，只需从我的数据库中读取即可。我被困了，任何帮助，示例代码等都会很棒。感谢

目前的错误是＆＃34; 错误CS1503参数1：无法转换为＆＃39; SQLite.TableQuery＆＃39;到＆＃39; int＆＃39; nutr_grabber C：\ Users \ Steve \ Documents \ Visual Studio 2015 \ Projects \ nutr_grabber \ nutr_grabber \ MainActivity.cs 53 Active＆＃34;

namespace nutr_grabber
{
    [Activity(Label = "nutr_grabber", MainLauncher = true, Icon = "@drawable/icon")]
public class MainActivity : Activity
{
    string str1;

    private static string DB_PATH = "/data/data/nutr_grabber/databases/";

    private static string DB_NAME = "UsdDataProto.db";

    private void copyDataBase()
    {
        var dbInput = ApplicationContext.Assets.Open(DB_NAME);
        string dbProto = DB_PATH + DB_NAME;
        var myOutput = new FileStream(dbProto, FileMode.OpenOrCreate);

        byte[] buffer = new byte[1024];
        int length;
        while ((length = dbInput.Read(buffer, 0, 1024)) > 0)
            myOutput.Write(buffer, 0, length);
        myOutput.Flush();
        myOutput.Close();
        dbInput.Close();
    }


    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);

        // Set our view from the "main" layout resource

        SetContentView(Resource.Layout.Main);


        //set widgets
        TextView message = FindViewById<TextView>(Resource.Id.message);
        EditText ingred = FindViewById<EditText>(Resource.Id.enterHere);
        Button search = FindViewById<Button>(Resource.Id.search);

        string proto = DB_PATH + DB_NAME;
        //string folder = System.Environment.GetFolderPath();
        var db = new SQLiteConnection(System.IO.Path.Combine( proto , "UsdDataProto.db"));
        db.CreateTable<usdProto>();



        search.Click += (object sender, EventArgs e) =>
        {
            str1 = ingred.Text;



            var Item = db.Query<usdProto>("SELECT Energ_Kcal FROM usdProto WHERE Shrt_Desc = ?", str1);



              new AlertDialog.Builder(this)
              .SetMessage(Item)
              .Show();


        };



    }
}



public class usdProto
{
    [PrimaryKey]

    public int NDB_No { get; set; }
    public string Shrt_Desc { get; set; }
    public int Energ_Kcal { get; set; }
    public int Protein_g { get; set; }
    public int Lipid_Tot_g { get; set; }
    public int Ash_g { get; set; }
    public int Carbohydrt_g { get; set; }

Answer 1

你的查询将返回一个IEnumerable对象，在你的情况下usdProto：

var query = db.Table<usdProto>().Where(v => v.Shrt_Desc.Contains(str1));

foreach (var item in query) {
  new AlertDialog.Builder(this)
            .SetMessage(item.SomeProperty)
            .Show();
}

将someProperty替换为您要显示的usdProto属性

Xamarin / Visual Studio 2015 - 我应该使用sqlite和查询问题，

1 个答案: