Xamarin.Forms Add and Share Item CrashApp

Xamarin.Forms Add and Share Item CrashApp - c#

Good morning to all, I've looked in several places I researched and did not found a solution that worked for my problems.
I'm new to C #, XAML and Xamarin, I am doing an application that creates lists with products on a screen, the screen with products is been populated via Json WebApi. Until there everthing looks fine, but since i tried to add 'ADD' and 'Share' functionalities it is loading the main page and crashes on navigating to listsPage.
I need to get a product from the product Page and add it to another view where my lists are. I created a ContextActions with 'Share' and 'AddToList' but i don't know how to get that product and 'Add' it to my lists. Same problem with 'Share' when i get the MenuItem and try to pass it to a Task in my ProductViewModel i get a NullReferenceException, but the object is not null.
I appreciate if someone could help me with this issues.
I know the post has got quite long but i wanted to give every possible info.
Here is my Lists Page:
<ListView x:Name="listaView" ItemSelected="listSelected" >
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.View>
<StackLayout Padding="20,0,20,0"
Orientation="Horizontal"
HorizontalOptions="FillAndExpand">
<Label Text="{Binding Name}"
VerticalTextAlignment="Center"
HorizontalOptions="StartAndExpand" />
<Image Source="check.png"
HorizontalOptions="Start"
IsVisible="{Binding Done}" />
</StackLayout>
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</ContentPage>
and my listDetail:
<Label Text="Name" />
<Entry x:Name="nameEntry" Text="{Binding Name}" />
<Label Text="Description" />
<Entry x:Name="descriptionEntry" Text="{Binding Description}" />
<Label Text="Typ" />
<controls:BindablePicker x:TypeArguments="enums:Typ" SelectedItem="{Binding Typ}" />
<Label Text="Done" />
<Switch x:Name="doneEntry" IsToggled="{Binding Done}" />
<Label Text="Products:" />
<ListView ItemsSource="{Binding Products}" >
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.View>
<StackLayout Orientation="Horizontal">
<Image Aspect="AspectFit" HeightRequest="20" WidthRequest="20" Source="{Binding Image}" />
<Label Text="{Binding Name}" />
<Label Text="{Binding Price, StringFormat='R${0:C2}'}" />
</StackLayout>
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<Button Text="Save" Clicked="salveClicked" />
<Button Text="Delete" Clicked="deleteClicked" />
<Button Text="Cancel" Clicked="cancelClicked" />
<Button Text="Speak" Clicked="speakClicked" />
</StackLayout>
</ContentPage>
ListDetails CODE BEHIND:
public ProductListDetailPage()
{
InitializeComponent();
NavigationPage.SetHasNavigationBar(this, true);
}
void saveClicked(object sender, EventArgs e)
{
var lista = (Lists)BindingContext;
App.Database.SaveList(lista);
this.Navigation.PopAsync();
}
void deleteClicked(object sender, EventArgs e)
{
var lista = (Lists)BindingContext;
App.Database.DeleteList(lista.ListaID);
this.Navigation.PopAsync();
}
void cancelClicked(object sender, EventArgs e)
{
var lista = (Lists)BindingContext;
this.Navigation.PopAsync();
}
void speakClicked(object sender, EventArgs e)
{
var lists = (Lists)BindingContext;
DependencyService.Get<ITextToSpeech>().Speak(lists.Name+ " " + lists.Descrip);
}
}
}
I believe the problem is in my model but have no idea what it is
Product Model:
public class Product : INotifyPropertyChanged
{
private int id;
public int ProductID
{
get { return id; }
set
{
id = value;
this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(id)));
}
}
private string name;
public string Name
{
get { return name; }
set
{
name= value;
this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(name)));
}
}
private double price;
public double Price{
get { return price; }
set
{
price= value;
this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(price)));
}
}
private string dtFab;
public string DtFab
{
get { return dtFab; }
set
{
dtFab= value;
this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(dtFab)));
}
}
private string dtValid;
public string DtValid {
get { return dtValid; }
set
{
dtValid= value;
this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(dtValid)));
}
}
private string amount;
public string Amount{
get { return quantidade; }
set
{
amount= value;
this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(amount)));
}
}
private string descrip;
public string Descrip{
get { return descrip; }
set
{
descrip= value;
this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(descrip)));
}
}
private string image;
public string Image
{
get { return image; }
set
{
image= value;
this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(image)));
}
}
private ICollection<ListProduct> listProduct;
public ICollection<ListProduct> ListProduct{
get { return listProduct; }
set
{
listProduct= value;
this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(listProduct)));
}
}
public event PropertyChangedEventHandler PropertyChanged;
}
}
ListsModel:
public class Lists
{
public Lista()
{
}
[PrimaryKey, AutoIncrement]
public int ListID get; set; }
public string Name { get; set; }
public string Descrip { get; set; }
public bool Done { get; set; }
public Typ Typ { get; set; }
public virtual ICollection<ListsProduct> ListsProducts{ get; set; }
}
public class ListsProduct
{
public int ListsProductID{ get; set; }
public int ListID { get; set; }
public int ProductID { get; set; }
public virtual Lists Lists { get; set; }
public virtual Product Product { get; set; }
}
}
ListProductModel:
SearchProductPage:
<StackLayout Orientation="Vertical">
<SearchBar Text="{Binding SearchBarText}" />
<Button x:Name="btnPesquisar" Text="Search" Command="{Binding SearchCommand}" />
<ListView ItemsSource="{Binding Products}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.ContextActions>
<MenuItem Text="Share" Clicked="ShareProduct" />
<MenuItem Text="Add To" Clicked="AddProduct" />
</ViewCell.ContextActions>
<ViewCell.View>
<StackLayout Orientation="Horizontal" HorizontalOptions="FillAndExpand" >
<Image Aspect="AspectFit" HeightRequest="20" WidthRequest="20" Source="{Binding Image}" />
<Label Text="{Binding Name}" />
<Label Text="{Binding Price, StringFormat='R${0:C2}'}" HorizontalOptions="End" />
</StackLayout>
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
</ContentPage>
SearchPage CODE BEHIND:
public partial class SearchPage: ContentPage
{
ProductsViewModel viewModel;
public TelaPesquisaView()
{
InitializeComponent();
this.BindingContext = new ViewModels.ProductsViewModel();
}
public async void AddProduct(object sender, EventArgs e)
{
var al = ((MenuItem)sender);
await viewModel.AddToList(al.BindingContext as Product);
var produtoLista = new ListsPage();
await Navigation.PushAsync(produtoLista);
}
public async void ShareProduct(object sender, EventArgs e)
{
var al = ((MenuItem)sender);
if (al != null) {
await viewModel.Share(al.BindingContext as Produto);
}
}
}
}
And the ProductViewModel
public class ProductViewModel : INotifyPropertyChanged
{
private string searchBarText = string.Empty;
public string SearchBarText {
get { return searchBarText ; }
set
{
if (searchBarText != value)
{
searchBarText = value ?? string.Empty;
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(searchBarText )));
if (SearchCommand.CanExecute(null))
{
SearchCommand.Execute(null);
}
}
}
}
// filtrar somente os 5 primeiros
#region Command SearchCommand
private Xamarin.Forms.Command searchCommand;
public ICommand SearchCommand{
get
{
searchCommand= searchCommand?? new Xamarin.Forms.Command(DoSearchCommand, ExecuteCommand);
return searchCommand;
}
set
{
searchCommand= (Xamarin.Forms.Command)value;
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(searchCommand)));
}
}
private void DoSearchCommand()
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Products)));
}
private bool ExecuteCommand()
{
return true;
}
#endregion
private ObservableCollection<Models.Produto> products;
public ObservableCollection<Models.Produto> Products {
get
{
ObservableCollection<Models.Product> searchProducts = new ObservableCollection<Models.Product>();
if (products != null)
{
List<Models.Product> prod = (from p in products
where p.Name.ToLower().Contains(searchBarText.ToLower())select p).Take(3).ToList<Models.Product>();
if (prod != null && prod.Any())
{
searchedProducts = new ObservableCollection<Models.Product>(prod);
}
}
return searchedProducts ;
}
set
{
products = value;
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Products)));
}
}
public ProductsViewModel()
{
SearchCommand = new Xamarin.Forms.Command(async () =>
{
var products = await ApiProducts.Api.GetAsync();
Products = new ObservableCollection<Models.Product>(products );
});
}
public async Task AddToList(ListsProduct prod)
{
Lists list = new Lists();
list.ListsProduct.Add(prod);
App.Database.SaveList(list);
}
public async Task Share(Models.Product prod)
{
var title = prod.NomeProduto;
var message = prod.ToString();
// Share message and an optional title.
await CrossShare.Current.Share(message, title );
}
public event PropertyChangedEventHandler PropertyChanged;
}
}

Here is the starting point for you. For the rest you can use the same pattern passing your new product in constructors or just implement setters in your view models.
Define binding to get a new product
<MenuItem Text="Adicionar à" Clicked="AdicionaProduto" CommandParameter="{Binding .}" />
Then pass it to your ListasView constructor as parameter
public async void AdicionaProduto(object sender, EventArgs e)
{
var al = ((MenuItem)sender);
var produtoLista = new ListasView(al.CommandParameter as Produto);
await Navigation.PushAsync(produtoLista);
}
To be able to do that you need to change a constructor
public ListasView(Produto newProduto = null)
{
InitializeComponent();
//this.BindingContext = new ViewModels.ListasViewModel();
if (newProduto != null)
{
//do something
int x = 0;
}
You can take that newProduto and store it in your DB or pass further to other models or views via constructor or some setters.

Related

Count selected checkboxes in collectionview xamarin

I have a collection view with a checkbox. I want to count the amount of checkboxes which have been selected and show that value in a label (string Sel). I think I have mostly done it however the label doesn't update. I think this is due to not calling OnProperty changed in the correct place which would update the label. I'm still rapping my head round MVVM. Thanks
ModelView:
public class MeetAWalkerViewModel : INotifyPropertyChanged
{
public ObservableCollection<PetProfile> source;
public ObservableCollection<PetProfile> PetInfo { get; private set; }
public ObservableCollection<PetProfile> EmptyPetInfo
{
get => source;
private set
{
if (value != source)
{
source = value;
OnPropertyChanged(nameof(EmptyPetInfo));
}
}
}
public string Sel { get; private set; }
public MeetAWalkerViewModel()
{
var count = EmptyPetInfo.Count(t => t.Selected);
Sel = "Amount of selected pets" + Convert.ToString(count);
}
#region INotifyPropertyChanged
public event PropertyChangedEventHandler PropertyChanged;
void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
#endregion
}
Xaml:
<CollectionView x:Name="petCollectionView" ItemsSource="{Binding EmptyPetInfo}">
<CollectionView.ItemTemplate>
<DataTemplate>
<Grid Padding="10" RowDefinitions="80" ColumnDefinitions="120,60,60">
<Image Grid.Column="0"
Grid.Row="0"
x:Name="PetImage"
Source="{Binding imageUrl}"/>
<Label Grid.Column="1"
Grid.Row="0"
Text="{Binding PetName}"
FontAttributes="Bold"
x:Name="labelpetname" VerticalTextAlignment="Center" HorizontalTextAlignment="Center"/>
<CheckBox Grid.Row="0" Grid.Column="2" HorizontalOptions="End" IsChecked="{Binding Selected, Mode=TwoWay}" CheckedChanged="CheckBox_CheckedChanged" BindingContext="{Binding .}"/>
</Grid>
</DataTemplate>
</CollectionView.ItemTemplate>
</CollectionView>

I made a sample based on your code, it works properly.
You can refer to the following code:
MeetAWalkerViewModel.cs
public class MeetAWalkerViewModel: INotifyPropertyChanged
{
public ObservableCollection<PetProfile> source;
//public ObservableCollection<PetProfile> PetInfo { get; private set; }
public ObservableCollection<PetProfile> EmptyPetInfo
{
get => source;
private set
{
if (value != source)
{
source = value;
OnPropertyChanged(nameof(EmptyPetInfo));
}
}
}
int _count;
public int Count
{
set
{
if (_count != value)
{
_count = value;
OnPropertyChanged(nameof(Count));
Sel = "Amount of selected pets is : " + Convert.ToString(_count);
}
}
get
{
return _count;
}
}
public void updateCount(int count) {
}
String sel;
public String Sel
{
set
{
if (sel != value)
{
sel = value;
OnPropertyChanged(nameof(Sel));
}
}
get
{
return sel;
}
}
public MeetAWalkerViewModel()
{
EmptyPetInfo = new ObservableCollection<PetProfile>();
EmptyPetInfo.Add(new PetProfile { PetName = "Pet1", IsSelected= false,ImageUrl= "cherry.png" });
EmptyPetInfo.Add(new PetProfile { PetName = "Pet2", IsSelected = false, ImageUrl = "watermelon.png" });
EmptyPetInfo.Add(new PetProfile { PetName = "Pet3", IsSelected = false, ImageUrl = "cherry.png" });
EmptyPetInfo.Add(new PetProfile { PetName = "Pet4", IsSelected = false, ImageUrl = "watermelon.png" });
EmptyPetInfo.Add(new PetProfile { PetName = "Pet5", IsSelected = false, ImageUrl = "cherry.png" });
EmptyPetInfo.Add(new PetProfile { PetName = "Pet6", IsSelected = false, ImageUrl = "watermelon.png" });
foreach (PetProfile petProfile in EmptyPetInfo) {
if (petProfile.IsSelected)
{
Count++;
}
}
Sel = "Amount of selected pets is : " + Convert.ToString(Count);
}
#region INotifyPropertyChanged
public event PropertyChangedEventHandler PropertyChanged;
void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
#endregion
}
MainPage.xaml
<StackLayout HorizontalOptions="Center" Padding="10" >
<Label x:Name="countSelectedItemsLabel" Text="{Binding Sel}" FontSize="20" />
<CollectionView x:Name="petCollectionView" ItemsSource="{Binding EmptyPetInfo}">
<CollectionView.ItemTemplate>
<DataTemplate>
<Grid Padding="10" RowDefinitions="80" ColumnDefinitions="120,60,60">
<Image Grid.Column="0"
Grid.Row="0"
x:Name="PetImage"
Source="{Binding ImageUrl}"/>
<Label Grid.Column="1"
Grid.Row="0"
Text="{Binding PetName}"
FontAttributes="Bold"
x:Name="labelpetname" VerticalTextAlignment="Center" HorizontalTextAlignment="Center"/>
<CheckBox Grid.Row="0" Grid.Column="2" HorizontalOptions="End" IsChecked="{Binding IsSelected, Mode=TwoWay}" CheckedChanged="CheckBox_CheckedChanged" BindingContext="{Binding .}"/>
</Grid>
</DataTemplate>
</CollectionView.ItemTemplate>
</CollectionView>
</StackLayout>
MainPage.xaml.cs
public partial class MainPage : ContentPage
{
MeetAWalkerViewModel viewModel;
int selectedCount = 0;
public MainPage()
{
InitializeComponent();
viewModel = new MeetAWalkerViewModel();
BindingContext = viewModel;
}
private void CheckBox_CheckedChanged(object sender, CheckedChangedEventArgs e)
{
PetProfile model = (PetProfile)((CheckBox)sender).BindingContext;
if (model.IsSelected)
{
selectedCount++;
}
else
{
selectedCount--;
}
viewModel.Count = selectedCount;
}
}
PetProfile.cs
public class PetProfile
{
public string PetName { get; set; }
public string ImageUrl { get; set; }
public bool IsSelected { get; set; }
}
The result is:

You need to change the String like this
String sel ;
public String Sel
{
set
{
if (sel != value)
{
sel = value;
OnPropertyChanged(nameof(Sel ));
}
}
get
{
return sel ;
}
}

Xamarin forms: System.InvalidCastException: 'Specified cast is not valid

I have a listview in xamarin and when i try to cast the selecteditem in a button clicked event it gives me the error. The class SavedVira is for a sqlite database table, i'm trying to use async but it seems to have been more trouble then worth. (i'm very new to programing). Here is my code:
XAML:
<ListView x:Name="SavedViraView" HasUnevenRows="True" ItemTapped="SavedViraView_ItemTapped">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.View>
<StackLayout Padding="10">
<Label Text="Navn:" FontSize="18" FontAttributes="Bold"/>
<Label Text="{Binding Virusnavn}" FontSize="15"/>
<Label Text="Symptomer:" FontSize="18" FontAttributes="Bold"/>
<Label Text="{Binding symptom1}"/>
<Label Text="{Binding symptom2}"/>
<Label Text="{Binding symptom3}"/>
<Label Text="{Binding symptom4}"/>
<Label Text="{Binding symptom5}"/>
<Label Text="{Binding symptom6}"/>
<Label Text="Lavet af:" FontSize="18" FontAttributes="Bold"/>
<Label Text="{Binding Creator}"/>
<Button Text="Load" x:Name="LoadButton" Clicked="LoadButton_Clicked"/>
</StackLayout>
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
XAML.CS:
private ObservableCollection<SavedVira> SavedVira = new ObservableCollection<SavedVira>();
public Åben()
{
InitializeComponent();
}
protected override void OnAppearing()
{
nameLabel.Text = Values.currentUser;
Init();
}
private async void Init()
{
BindingContext = new SavedVira();
var Viralist = await DataServices.GetSavedVira();
SavedVira = new ObservableCollection<SavedVira>(Viralist);
SavedViraView.ItemsSource = SavedVira;
}
private void LoadButton_Clicked(object sender, EventArgs e)
{
var LoadVirus = ((ListView)sender).SelectedItem as SavedVira;
if (LoadVirus == null)
return;
Values.LoadBool = true;
Values.symptomZero = LoadVirus.symptom1;
Values.symptomOne = LoadVirus.symptom2;
Values.symptomTwo = LoadVirus.symptom3;
Values.symptomThree = LoadVirus.symptom4;
Values.symptomFour = LoadVirus.symptom5;
Values.symptomFive = LoadVirus.symptom6;
}
SavedVira cast/model:
[Table("savedvira")]
public class SavedVira
{
[PrimaryKey, AutoIncrement]
[Column("id")]
public int Id { get; set; }
[Column("virusnavn")]
public string Virusnavn { get; set; }
[Column("creator")]
public string Creator { get; set; }
[Column("symptoms1")]
public string symptom1 { get; set; }
[Column("symptoms2")]
public string symptom2 { get; set; }
[Column("symptoms3")]
public string symptom3 { get; set; }
[Column("symptoms4")]
public string symptom4 { get; set; }
[Column("symptoms5")]
public string symptom5 { get; set; }
[Column("symptoms6")]
public string symptom6 { get; set; }
}
Any help would be grealty appriciated!

the sender is a Button so this doesn't work
var LoadVirus = ((ListView)sender).SelectedItem as SavedVira;
instead do this
var btn = (Button)sender;
var selected = (SavedVira)btn.BindingContext;
also, using the same name for an instance variable and a class is confusing, I'd suggest you avoid it
SavedVira = new ObservableCollection<SavedVira>(Viralist);

Trying to set picker within listview MVVM Xamarin

Trying to set the initial value to a picker through the use of SelectedItem. I can do this without any issue if the picker isn't within a listview. However, once I try to accomplish this in a listview no dice.
I never can get the picker to display the initially downloaded value. If I use the same binding for an entry it displays the expected string.
Thoughts??
This can be reproduced in this simplistic standalone project. Please help. Thanks.
https://github.com/smarcus3/DebuggingProject
XAML
<ListView x:Name="listView" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand" ItemsSource="{Binding downloadedRecipeIngredients}"> <!--SelectedItem="{Binding SelectedItem}"-->
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout Orientation="Horizontal">
<!-- Element Label -->
<Entry VerticalOptions="CenterAndExpand" HorizontalOptions="StartAndExpand" Text="{Binding IngredientName}"/>
<!--<Picker x:Name="pickerIngredient" HorizontalOptions = "StartAndExpand" ItemsSource="{Binding listIngredients}" BindingContext="{Binding Source={x:Reference Page}, Path=BindingContext}" SelectedItem="{Binding IngredientName}" WidthRequest="100"/>-->
<Picker x:Name="pickerIngredientancestor" HorizontalOptions = "StartAndExpand" WidthRequest="100" ItemsSource="{Binding listIngredients, Source={RelativeSource AncestorType={x:Type viewModel:testPageViewModel}}}" SelectedItem="{Binding IngredientName}"/>
<Entry Text="{Binding Quantity}" VerticalOptions="CenterAndExpand" HorizontalOptions="StartAndExpand" />
<Entry Text="{Binding UnitName}" VerticalOptions="CenterAndExpand" HorizontalOptions="StartAndExpand" />
<Entry Text="{Binding Comments}" VerticalOptions="CenterAndExpand" HorizontalOptions="StartAndExpand" />
<!-- Assessment Menu Icon -->
<Label Text="Clickable Label" VerticalOptions="CenterAndExpand" HorizontalOptions="EndAndExpand">
<Label.GestureRecognizers>
<TapGestureRecognizer Command="{Binding Path=BindingContext.btnPress, Source={x:Reference Page}}" CommandParameter="{Binding .}" />
</Label.GestureRecognizers>
</Label>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
VIEW MODEL
public class testPageViewModel : BaseViewModel
{
clRecipeIngredient[] _downloadedRecipeIngredients;
public clRecipeIngredient[] downloadedRecipeIngredients
{
get {
return _downloadedRecipeIngredients;
}
set
{
//if (downloadedRecipeIngredients != value)
//{
_downloadedRecipeIngredients = value;
OnPropertyChanged("downloadedRecipeIngredients");
//}
}
}
//Lists for Pickers
ObservableCollection<string> _listIngredients = new ObservableCollection<string>();
public ObservableCollection<string> listIngredients { get { return _listIngredients; } }
private clRecipeDataBase recipeDataBase;
public testPageViewModel()
{
recipeDataBase = new clRecipeDataBase();
btnPress = new Command<clRecipeIngredient>(madeIt);
getData();
}
async void getData()
{
//PICKER INGREDIENT DATA
clIngredient[] tmp = await recipeDataBase.getIngredientData();
for (int i = 0; i < tmp.Length; i++)
{
_listIngredients.Add(tmp[i].IngredientName);
}
_downloadedRecipeIngredients = await recipeDataBase.getRecipeIngredientsDataByRecipeID(310); //HARDCODED TO CRISPY PIZZA RECIPE
OnPropertyChanged("downloadedRecipeIngredients");
}
public ICommand btnPress { get; private set; }
void madeIt(clRecipeIngredient x)
{
Console.WriteLine(x.IngredientName + " -- " + x.Comments);
//_downloadedRecipeIngredients.Remove(x);
}
}
clRecipeIngredients
public class clRecipeIngredient
{
public int RecipeIngredientsID { get; set; }
public int RecipeIDLookedUP { get; set; }
public int IngredientIDLookedUp { get; set; }
public double Quantity { get; set; }
public int UnitIDLookedUp { get; set; }
public bool HiddenFlag { get; set; }
public string UnitName { get; set; }
public string IngredientName { get; set; }
public string Comments { get; set; }

I checked your sample and you could modify it like following .
in Xaml
<Picker HorizontalOptions = "StartAndExpand" WidthRequest="100" ItemsSource="{Binding Path=BindingContext.listIngredients, Source={x:Reference Page}}" SelectedItem="{Binding IngredientName, Mode=TwoWay}" />
in ViewModel
ObservableCollection had implemented the interface INotifyPropertyChanged in default . So you could simplify the code in your ViewModel .
Note : You could not set the value of SelectItem as a string directly even if they are equal . You need to set it like following
ing.IngredientName = listIngredients[0];
So the ViewModel could like
public class testPageViewModel : BaseViewModel
{
public ObservableCollection<clRecipeIngredient> downloadedRecipeIngredients
{
get;set;
}
public ObservableCollection<string> listIngredients { get; set; }
//private clRecipeDataBase recipeDataBase;
public testPageViewModel()
{
//recipeDataBase = new clRecipeDataBase();
btnPress = new Command<clRecipeIngredient>(madeIt);
downloadedRecipeIngredients = new ObservableCollection<clRecipeIngredient>();
listIngredients = new ObservableCollection<string>();
getData();
}
async void getData()
{
//PICKER INGREDIENT DATA
//clIngredient[] arrayIngredients = await recipeDataBase.getIngredientData();
//clIngredient[] arrayIngredients = new clIngredient[5];
//arrayIngredients[0].IngredientName = "Apple";
//arrayIngredients[1].IngredientName = "Salt";
//arrayIngredients[2].IngredientName = "Buuter";
//arrayIngredients[3].IngredientName = "Flour";
//arrayIngredients[4].IngredientName = "Egg";
listIngredients.Add("Apple");
listIngredients.Add("Salt");
listIngredients.Add("Butter");
listIngredients.Add("Flour");
listIngredients.Add("Egg");
//for (int i = 0; i < arrayIngredients.Length; i++)
//{
// _listIngredients.Add(arrayIngredients[i].IngredientName);
//}
//clRecipeIngredient[] arryRecipeIngredients = await recipeDataBase.getRecipeIngredientsDataByRecipeID(310); //HARDCODED TO CRISPY PIZZA RECIPE
clRecipeIngredient ing = new clRecipeIngredient();
ing.IngredientName = listIngredients[0];
ing.Quantity = 1;
ing.UnitName = "Cups";
ing.Comments = "Comments0";
clRecipeIngredient ing2 = new clRecipeIngredient();
ing2.IngredientName = listIngredients[1];
ing2.Quantity = 2;
ing2.UnitName = "Whole";
ing2.Comments = "Comments1";
downloadedRecipeIngredients.Add(ing);
downloadedRecipeIngredients.Add(ing2);
}
public ICommand btnPress { get; private set; }
void madeIt(clRecipeIngredient x)
{
Console.WriteLine(x.IngredientName + " -- " + x.Comments);
//_downloadedRecipeIngredients.Remove(x);
}
}
And don't forget to implement INotifyPropertyChanged in your model as the value of IngredientName will been changed .
public class clRecipeIngredient : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(
[CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this,new PropertyChangedEventArgs(propertyName));
}
//...
string ingredientName;
public string IngredientName
{
get
{
return ingredientName;
}
set
{
if (ingredientName != value)
{
ingredientName = value;
OnPropertyChanged("IngredientName");
}
}
}
//...
}

Its still unclear why you cannot directly set the selectedItem with a string as I can do in pickers not inside of a ListView.
However, setting the picker to use the SelectedIndex property works great. This is the KEY. For ListView's containing pickers I will not set their value based on INDEX instead of SelectedItem.
Final Code Snippets
XAML
<Picker HorizontalOptions = "StartAndExpand" WidthRequest="100" ItemsSource="{Binding Path=BindingContext.listIngredients, Source={x:Reference Page}}" SelectedIndex="{Binding IngredientIDLookedUp}" />
View Model
clRecipeIngredient[] arryRecipeIngredients = await recipeDataBase.getRecipeIngredientsDataByRecipeID(310); //HARDCODED TO CRISPY PIZZA RECIPE
clRecipeIngredient ing = new clRecipeIngredient();
_downloadedRecipeIngredients.Clear();
for (int i = 0;i < arryRecipeIngredients.Length;i++)
{
for (int j=0; j<_listIngredients.Count;j++)
{
//FIND THE SELECTED INDEX BASED ON PICKER’S LIST and STORE IN THE CUSTOM CLASS
if(arryRecipeIngredients[i].IngredientName == _listIngredients[j])
{
arryRecipeIngredients[i].IngredientIDLookedUp = j;
}
}
_downloadedRecipeIngredients.Add(arryRecipeIngredients[i]);
}

Xamarin.Forms data binding

Is there any chance to get access from code behind to picker inside my listview/listview.itemtemplate/datatemplate/viewcell ?
First I want to get rid of x:Array String, then I want to get data from database and bind to my picker in OnApearing() method, after I select picker data it will update my database
<Picker Title="Select text"
x:Name="Picker"
HorizontalOptions="StartAndExpand"
VerticalOptions="Center"
FontSize="20"
SelectedIndexChanged="Picker_SelectedIndexChanged">
<Picker.ItemsSource>
<x:Array Type="{x:Type x:String}">
<x:String>Text1</x:String>
<x:String>Text2</x:String>
<x:String>Text3</x:String>
<x:String>Text4</x:String>
</x:Array>
</Picker.ItemsSource>
</Picker>
Thanks for help :)

You could use list in list when the picker is in the ViewCell
<ListView ItemsSource="{Binding MyItems}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Grid BackgroundColor="#eee" >
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Label Grid.Row="0" Text="{Binding Content}" TextColor="Red" />
<Picker Grid.Row="1" ItemsSource="{Binding PickerSource}" SelectedItem="{Binding SelectedValue}" />
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
in code behind
in ViewModel
public class MyViewModel: INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public ObservableCollection<MyModel> MyItems { get; set; }
public MyViewModel()
{
// I used local data just for demo, you could get it from DB
MyItems = new ObservableCollection<MyModel>()
{
new MyModel(){Content="items1",PickerSource = new ObservableCollection<string>(){"option1","option2","option3" } },
new MyModel(){Content="items2",PickerSource = new ObservableCollection<string>(){"option1","option2","option3" } },
new MyModel(){Content="items3",PickerSource = new ObservableCollection<string>(){"option1","option2","option3" } },
new MyModel(){Content="items4",PickerSource = new ObservableCollection<string>(){"option1","option2","option3" } },
new MyModel(){Content="items5",PickerSource = new ObservableCollection<string>(){"option1","option2","option3" } },
new MyModel(){Content="items6",PickerSource = new ObservableCollection<string>(){"option1","option2","option3" } },
new MyModel(){Content="items7",PickerSource = new ObservableCollection<string>(){"option1","option2","option3" } },
};
foreach(var model in MyItems)
{
model.PropertyChanged += Model_PropertyChanged;
}
}
private void Model_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
if(e.PropertyName== "SelectedValue")
{
var SelectedModel = sender as MyModel;
var SelectedValue = SelectedModel.SelectedValue;
//... do something you want
}
}
}
in Model
public class MyModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public ObservableCollection<string> PickerSource { get; set; }
public string Content { get; set; }
string selectedValue;
public string SelectedValue
{
get { return selectedValue; }
set
{
selectedValue = value;
NotifyPropertyChanged("SelectedValue");
}
}
//other properties
}

Xamarin Forms Picker Binding

I'd like to implement a simple picker XAML binded to 3 labels, where when I choose a value from the picker the labels will be populated automatically (the data comes from SQLite).
Here is what I have:
<Picker x:Name="ListJobs" Title="Select Job" ItemsSource="{Binding options}" ItemDisplayBinding="{Binding JobNo}" SelectedItem="{Binding SelectedJobs}"/>
<Label Text="{Binding JobsId}" IsVisible="True" x:Name="TxtId"/>
<Label Text="{Binding name}" IsVisible="True" x:Name="TxtName"/>
<Label Text="{Binding location}" IsVisible="True" x:Name="TxtLoc"/>
Model
public class Jobs
{
public string JobsId {get;set;}
public string name {get;set;}
public string location {get;set;}
public Jobs(){}
}
Code Behind:
protected override OnAppearing()
{
jobsInfo = (List<Jobs>) GetJob();
foreach (var item in jobsInfo)
{
Jobs options = new Jobs
{
JobsId = item.JobsId,
name = item.name,
location = item.location
};
BindingContext = options;
}
}
private IEnumerable<Jobs> GetJobsInfo()
{
var db = _connection.Table<Jobs>();
return db.ToList();
}
I would to select from picker (like dropdown) and populate the labels.

First, there are some mistakes in your code.
1.When you go through the loop (the data you gained from db), options is always updated with new data(so it generates using last object), and you set it to BindingContext. You should set a modelView here rather a model.
2.The itemSource of Picker must be a list, however you set a model here.
3.The viewmodel must implement INotifyPropertyChanged to notify the changes.
I think what you need understanding most is not this Picker , it is How to work with binding.
Bindable Properties
Data Binding Basics
From Data Bindings to MVVM
Okay, let us come back to this case. What you need is here
I simplified the demo and you can refer to it.
XAML
<Picker x:Name="picker"
Title="Select Job"
ItemsSource="{Binding JobList}"
ItemDisplayBinding="{Binding Name}"
SelectedItem="{Binding SelectedJob}"/>
<Label Text="{Binding SelectedJob.JobsId}" IsVisible="True" x:Name="TxtId" Margin="0,100,0,0"/>
<Label Text="{Binding SelectedJob.Name}" IsVisible="True" x:Name="TxtName"/>
<Label Text="{Binding SelectedJob.Location}" IsVisible="True" x:Name="TxtLoc"/>
Model and ViewModel:
public class Jobs
{
public string JobsId { get; set; }
public string Name { get; set; }
public string Location { get; set; }
}
public class RootModel : INotifyPropertyChanged
{
List<Jobs> jobList;
public List<Jobs> JobList
{
get { return jobList; }
set
{
if (jobList != value)
{
jobList = value;
OnPropertyChanged();
}
}
}
Jobs selectedJob;
public Jobs SelectedJob
{
get { return selectedJob; }
set
{
if (selectedJob != value)
{
selectedJob = value;
OnPropertyChanged();
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
}
Code behind:
public MainPage()
{
InitializeComponent();
this.BindingContext = new RootModel
{
JobList = GetJobsInfo()
};
}
private List<Jobs> GetJobsInfo()
{
var db = _connection.Table<Jobs>();
return db.ToList();
}
My Test:

XAML:
<Picker x:Name="ListJobs" Title="Select Job" ItemsSource="{Binding AllJobs}"
ItemDisplayBinding="{Binding Name}" SelectedItem="{Binding SelectedJob}"/>
<Label Text="{Binding SelectedJob.JobId}" IsVisible="True" x:Name="TxtId"/>
<Label Text="{Binding SelectedJob.Name}" IsVisible="True" x:Name="TxtName"/>
<Label Text="{Binding SelectedJob.Location}" IsVisible="True" x:Name="TxtLoc"/>
Model:
public class Job
{
public string JobId { get; set; }
public string Name { get; set; }
public string Location {get; set; }
}
public class JobModel
{
public List<Job> AllJobs { get; set; }
public Job SelectedJob { get; set; }
}
Code behind:
protected override OnAppearing()
{
BindingContext = new JobsModel {
AllJobs = GetJobs()
};
}
private List<Jobs> GetJobs()
{
var db = _connection.Table<Jobs>();
return db.ToList();
}

//How to add picker or dropdownlist in Xamarin forms and bind text ?
//we will be using Picker Properties -> pickername.ItemsSource and pickername.SelectedItem
//In above line pickername is the x:Name given to picker
//page.xaml
<Frame CornerRadius="5" HeightRequest="50" Padding="0">
<StackLayout Orientation="Horizontal">
<controls:BorderlessPicker
x:Name="Pickdoctype"
ItemDisplayBinding="{Binding text}"
SelectedIndexChanged="Pickdoctype_SelectedIndexChanged"
HorizontalOptions="FillAndExpand"
Title="Enter Document Type"
FontSize="20"
TextColor="Gray">
</controls:BorderlessPicker>
<ImageButton BackgroundColor="Transparent" Padding="0">
<ImageButton.Source>
<FontImageSource Glyph="" Size="25"
FontFamily="{StaticResource FontAwesomeSolid}"
Color="Gray"></FontImageSource>
</ImageButton.Source>
</ImageButton>
</StackLayout>
</Frame>
//page.xaml.cs
//Picker Get API
var responseUserData = await httpService.Get("manageDocument/documentType/documentType/" + UserID);
if (responseUserData.IsSuccessStatusCode)
{
var responseUserDataString = await responseUserData.Content.ReadAsStringAsync();
var myDeserializedClass = JsonConvert.DeserializeObject<List<DocumentTypeModel>>(responseUserDataString);
Pickdoctype.ItemsSource = myDeserializedClass;
}
//Get Picker value functionality
private void Pickdoctype_SelectedIndexChanged(object sender, EventArgs e)
{
try
{
DocumentTypeModel selectedItem = (DocumentTypeModel)Pickdoctype.SelectedItem;
string PickerValue = selectedItem.value;
string PickerText = selectedItem.text;
}
catch (Exception ex)
{
}
}
//Create a model class
public class DocumentTypeModel
{
public string masterName { get; set; }
public string text { get; set; }
public string value { get; set; }
}

Develop Reference

C# (C-Sharp) is a programming language developed by Microsoft that runs on the .NET Framework.

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