如何使用linq where子句填充xamarin.forms中的listview

Question

I'm working on a simple project which i want to search bar to fill a listview base on user input. But this is the error code that shows:

Severity Code Description Project File Line Suppression State Error CS7036: There is no argument given that corresponds to the required formal parameter 'Chiefdom'

In my sqlitehelper this what my task query.

public Task<CommodityList> GetSearchComoditylistAsync(string Chiefdom)
{
    return db.Table<CommodityList>().Where(i => i.Chiefdom == Chiefdom).FirstOrDefaultAsync();
}

In my cs page this what I have:

async void SearchBar_Pressed(object sender, EventArgs e)
{
    var comoList = await App.SQLiteDb.GetSearchComoditylistAsync();
    if (comoList != null)
    {
        lvChiefCommodity.ItemsSource = comoList;
    }
}

All what I want is when ever a user input or enter something into the search bar and hit enter key it should fill the listview according to the input.

Answer 1

GetSearchComoditylistAsync has one required parameter, Chiefdom

public Task<CommodityList> GetSearchComoditylistAsync(string Chiefdom)
{
    return db.Table<CommodityList>().Where(i => i.Chiefdom == Chiefdom).FirstOrDefaultAsync();
}

but when you call it you are not passing any parameters

async void SearchBar_Pressed(object sender, EventArgs e)
{
    var comoList = await App.SQLiteDb.GetSearchComoditylistAsync();

you presumably want to pass in the search string

var search = (SearchBar)sender;
var comoList = await App.SQLiteDb.GetSearchComoditylistAsync(search.Text);

your current search function only returns ONE result. If you want to return more than that,

return db.Table<CommodityList>().Where(i => i.Chiefdom.ToUpper().Contains(Chiefdom.ToUpper()).ToListAsync();

Answer 2

public Task> GetItemsNotDoneAsync(string Chiefdom) { return db.QueryAsync("SELECT * FROM CommodityList WHERE Chiefdom=?",Chiefdom); }