Xamarin forms: How to add a contentpage having arguments into a list?

Sreeee · June 2019

I am implementing the Navigation Drawer on my project. I am following this blog for this feature.

Mainpage.xsml.cs:

public partial class NavigationDrawerPage : MasterDetailPage
    {
public List<MasterPageItem> menuList { get; set; }
        public MainPage()
        {
            InitializeComponent();

            menuList = new List<MasterPageItem>();

            // Adding menu items to menuList and you can define title ,page and icon
            menuList.Add(new MasterPageItem() { Title = "Home", Icon = "home.png", TargetType = typeof(HomePage) });
            menuList.Add(new MasterPageItem() { Title = "Setting", Icon = "setting.png", TargetType = typeof(SettingPage) });
            menuList.Add(new MasterPageItem() { Title = "LogOut", Icon = "logout.png", TargetType = typeof(LogoutPage) });

            navigationDrawerList.ItemsSource = menuList;

            Detail = new NavigationPage((Page)Activator.CreateInstance(typeof(HomePage)));
        }
}

Mainpage.xaml

<StackLayout Grid.Row="1" Spacing="15">
                    <ListView x:Name="navigationDrawerList"
                  RowHeight="60"
                  SeparatorVisibility="None"
                  BackgroundColor="#e8e8e8"
                  ItemSelected="OnMenuItemSelected">

                        <ListView.ItemTemplate>
                            <DataTemplate>
                                <ViewCell>
                                    <StackLayout>
                                        <!-- Main design for our menu items -->
                                        <StackLayout VerticalOptions="FillAndExpand"
                             Orientation="Horizontal"
                             Padding="20,10,0,10"
                             Spacing="20">

                                            <Image Source="{Binding Icon}"
                         WidthRequest="30"
                         HeightRequest="30"
                         VerticalOptions="Center" />

                                            <Label Text="{Binding Title}"
                         FontSize="Medium"
                         VerticalOptions="Center"
                         TextColor="Black"/>
                                        </StackLayout>
                                        <BoxView HeightRequest="1" BackgroundColor="Gray"/>
                                    </StackLayout>
                                </ViewCell>
                            </DataTemplate>
                        </ListView.ItemTemplate>
                    </ListView>
                </StackLayout>

MasterPageItem.cs

public class MasterPageItem
    {
        public string Title { get; set; }
        public string Icon { get; set; }
        public Type TargetType { get; set; }
    }

My problem is when adding my content pages to list. The above code working perfect:

menuList.Add(new MasterPageItem() { Title = "Home", Icon = "home.png", TargetType = typeof(SettingPage) });

But I have a page having one argument, I can't add the argument inside of the TargetType. See the below code:

menuList.Add(new MasterPageItem() { Title = "Help", Icon = "help.png", TargetType = typeof(HelpPage(false)) });  //showing syntax errors for this line

How can I add a content page having arguments into the list item? Should I change the TargetType datatype?

ColeX · June 2019

You could pass parameters with the method public static object CreateInstance(Type type, params object[] args);

Item

public class MasterPageItem
{
    public string Title { get; set; }
    public string Icon { get; set; }
    public Type TargetType { get; set; }

    public object[] args { get; set; }   //
}

MasterDetailPage

menuList.Add(new MasterPageItem() { Title = "Home", Icon = "home.png", TargetType = typeof(HomePage), args = new object[] {"string", 1 , false} } ); // pass parameters whatever you want

Add the constructor with corresponding parameters

public HomePage()   //remain the default constructor 
{
    InitializeComponent();
}

public HomePage (string s , int i , bool b)   //add this
{
    InitializeComponent ();
}

My test

ColeX · June 2019

Have you remained the Default constructor with MyTabbedPage ?

Check if the following method in MyTabbedPage.cs

  public MyTabbedPage()
    {
        InitializeComponent();
    }

ColeX · June 2019

No better way , you could hard code here

Detail = new NavigationPage((Page)Activator.CreateInstance(typeof(HomePage), new object[] { "string", 1, false }));

ColeX · June 2019

If you only need bool value , just pass one parameter.

 Detail = new NavigationPage((Page)Activator.CreateInstance(typeof(Homepage), new object[] { false }));

And change the constructor with only one parameter

public HomePage (bool b)   //add this
{
    InitializeComponent ();
}

ColeX · June 2019

Detail = new NavigationPage((Page)Activator.CreateInstance(page));
Detail = new NavigationPage((Page)Activator.CreateInstance(page,item.args));

If you call the first one , it always hits the default constructor (without argument).

If you call the second one , it hits the constructor with arguments (it is determined by the parameters passed in the MasterPageItem)

Change the code in item selected event

private void OnMenuItemSelected(object sender, SelectedItemChangedEventArgs e)
    {
        var item = (MasterPageItem)e.SelectedItem;
        Type page = item.TargetType;
        Detail = new NavigationPage((Page)Activator.CreateInstance(page,item.args));   //this line
        IsPresented = false;
    }

If

menuList.Add(new MasterPageItem() { Title = "Announcements", Icon = "ic_topics_fill_xx.png", TargetType = typeof(HomePage), args = new object[] { "bool", 1, false } });

it hits

public HomePage (string s , int i , bool b)  
{
    InitializeComponent ();
}

If

menuList.Add(new MasterPageItem() { Title = "Announcements", Icon = "ic_topics_fill_xx.png", TargetType = typeof(HomePage), args = new object[] { false } });

it hits

 public HomePage ( bool b)  
{
    InitializeComponent ();
}

If

menuList.Add(new MasterPageItem() { Title = "Announcements", Icon = "ic_topics_fill_xx.png", TargetType = typeof(HomePage)});

it hits

public HomePage ()   //default constructor
{
    InitializeComponent ();
}

Is it clear ?

ColeX · June 2019

.............

It should be Detail = new NavigationPage((Page)Activator.CreateInstance(page,item.args));

ClintStLaurent · June 2019

Personally I'd put those traits on the ViewModel for the pages.
Then you don't need the extra class of MasterPageItem. Just use the ViewModels as your collection.
And your other classes aren't responsible for creating items and setting the properties. IE: Why would your NavigationDrawer be responsible for setting the titles and icons of _other_pages? It shouldn't know or control these things.

Sreeee · June 2019

@ClintStLaurent Can you share sample codes?

ColeX · June 2019

You could pass parameters with the method public static object CreateInstance(Type type, params object[] args);

Item

public class MasterPageItem
{
    public string Title { get; set; }
    public string Icon { get; set; }
    public Type TargetType { get; set; }

    public object[] args { get; set; }   //
}

MasterDetailPage

menuList.Add(new MasterPageItem() { Title = "Home", Icon = "home.png", TargetType = typeof(HomePage), args = new object[] {"string", 1 , false} } ); // pass parameters whatever you want

Add the constructor with corresponding parameters

public HomePage()   //remain the default constructor 
{
    InitializeComponent();
}

public HomePage (string s , int i , bool b)   //add this
{
    InitializeComponent ();
}

My test

Sreeee · June 2019

menuList.Add(new MasterPageItem() { Title = "Announcements", Icon = "ic_topics_fill_xx.png", TargetType = typeof(HomePage), args = new object[] { "bool", 1, false } });

Hi @ColeX tried like above, my argument is a bool variable. but getting following Exception.

Unhandled Exception:
System.MissingMethodException: Default constructor not found for type appname.MyTabbedPage

ColeX · June 2019

Have you remained the Default constructor with MyTabbedPage ?

Check if the following method in MyTabbedPage.cs

  public MyTabbedPage()
    {
        InitializeComponent();
    }

ClintStLaurent · June 2019

@Sreeee said:
@ClintStLaurent Can you share sample codes?

Samples of... ? Ya lost me. Sample of a property called "Title"? I don't understand what it is you want a sample of. If its just a matter of understanding MVVM, base classes for view models etc. you can hit up my tutorials.
http://redpillxamarin.com/2018/03/12/2018-101-vs2017-new-solution/

Sreeee · June 2019

@ColeX It is working. One last question.

// Initial navigation, this can be used for our home page
    Detail = new NavigationPage((Page)Activator.CreateInstance(typeof(HomePage)));

For the initial navigation, I am using the above code. So the same argument needs to pass here also, how can I do that here?

ColeX · June 2019

No better way , you could hard code here

Detail = new NavigationPage((Page)Activator.CreateInstance(typeof(HomePage), new object[] { "string", 1, false }));

Sreeee · June 2019

@ColeX Why passing "string"? { "string", 1, false })); Actually it is a bool variable, so can I pass like below?

Detail = new NavigationPage((Page)Activator.CreateInstance(typeof(Homepage), new object[] { "bool", 1, false }));

ColeX · June 2019

If you only need bool value , just pass one parameter.

 Detail = new NavigationPage((Page)Activator.CreateInstance(typeof(Homepage), new object[] { false }));

And change the constructor with only one parameter

public HomePage (bool b)   //add this
{
    InitializeComponent ();
}

NMackay · June 2019

Eeeek, I'd be rejecting that pull request

Prism makes these scenarios really simple.
https://prismlibrary.github.io/docs/xamarin-forms/navigation/passing-parameters.html

Sreeee · June 2019

@ColeX The initial navigation part is working fine and I can see the contents on the page. But when I select an item from navigation drawer the page is not loading. I am using the following code when selecting an item from the navigation drawer.

<ListView x:Name="navigationDrawerList"
                  ItemSelected="OnMenuItemSelected">

private void OnMenuItemSelected(object sender, SelectedItemChangedEventArgs e)
        {
            var item = (MasterPageItem)e.SelectedItem;
            Type page = item.TargetType;
            Detail = new NavigationPage((Page)Activator.CreateInstance(page));
            IsPresented = false;
        }

Code execution is coming on the Homepage and but invoking the constructor without argument.

public HomePage()  
{
    InitializeComponent();
}

Sreeee · June 2019

@ColeX The code execution is coming on the Homepage but invoking the constructor without argument. So is that mean our code for adding arguments to the page is not correct. I try both ways(added below) for adding arguments, but always hitting the constructor without argument.

menuList.Add(new MasterPageItem() { Title = "Announcements", Icon = "ic_topics_fill_xx.png", TargetType = typeof(HomePage), args = new object[] { "bool", 1, false } });

menuList.Add(new MasterPageItem() { Title = "Announcements", Icon = "ic_topics_fill_xx.png", TargetType = typeof(HomePage), args = new object[] { false } });

ColeX · June 2019

Detail = new NavigationPage((Page)Activator.CreateInstance(page));
Detail = new NavigationPage((Page)Activator.CreateInstance(page,item.args));

If you call the first one , it always hits the default constructor (without argument).

If you call the second one , it hits the constructor with arguments (it is determined by the parameters passed in the MasterPageItem)

Change the code in item selected event

private void OnMenuItemSelected(object sender, SelectedItemChangedEventArgs e)
    {
        var item = (MasterPageItem)e.SelectedItem;
        Type page = item.TargetType;
        Detail = new NavigationPage((Page)Activator.CreateInstance(page,item.args));   //this line
        IsPresented = false;
    }

If

menuList.Add(new MasterPageItem() { Title = "Announcements", Icon = "ic_topics_fill_xx.png", TargetType = typeof(HomePage), args = new object[] { "bool", 1, false } });

it hits

public HomePage (string s , int i , bool b)  
{
    InitializeComponent ();
}

If

menuList.Add(new MasterPageItem() { Title = "Announcements", Icon = "ic_topics_fill_xx.png", TargetType = typeof(HomePage), args = new object[] { false } });

it hits

 public HomePage ( bool b)  
{
    InitializeComponent ();
}

If

menuList.Add(new MasterPageItem() { Title = "Announcements", Icon = "ic_topics_fill_xx.png", TargetType = typeof(HomePage)});

it hits

public HomePage ()   //default constructor
{
    InitializeComponent ();
}

Is it clear ?

Sreeee · June 2019

@ColeX I tried like below but showing `NavigationPage' does not contain a constructor that takes 2 arguments.

Detail = new NavigationPage((Page)Activator.CreateInstance(page), item.args);

Screenshot:

ColeX · June 2019

.............

It should be Detail = new NavigationPage((Page)Activator.CreateInstance(page,item.args));

Sreeee · June 2019

Hi @ColeX

Today I tested the navigation drawer feature in ios and UWP. In ios a blue box is showing on each pages of drawer items. See the screenshot below:

In UWP the navigation drawer is not dismissing after selecting an item from it.

I searched a lot, Can you suggest any solution for these 2 issues?

ColeX · June 2019

@Sreeee said:
Hi @ColeX

Today I tested the navigation drawer feature in ios and UWP. In ios a blue box is showing on each pages of drawer items. See the screenshot below:

In UWP the navigation drawer is not dismissing after selecting an item from it.

I searched a lot, Can you suggest any solution for these 2 issues?

This is a another question , could you open a new thread ?

Sreeee · June 2019

@ColeX Sure.
Started a new thread here.

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Xamarin forms: How to add a contentpage having arguments into a list?

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MasterDetailPage

Add the constructor with corresponding parameters

My test

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Item

MasterDetailPage

Add the constructor with corresponding parameters

My test