c# - Xamarin.form Page Navigation in mvvm -


i working on xamarin.form cross-platform application , want navigate 1 page on button click. cannot navigation.pushasync(new page2()); in viewmodel because possible in code-behid file. please suggest way this?

here view:

<?xml version="1.0" encoding="utf-8" ?> <contentpage xmlns="http://xamarin.com/schemas/2014/forms"              xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"              x:class="calculator.views.signin"              xmlns:viewmodels="clr-namespace:calculator.viewmodels;assembly=calculator">      <contentpage.bindingcontext>         <viewmodels:localaccountviewmodel/>     </contentpage.bindingcontext>      <contentpage.content>              <stacklayout>                 <button command="{binding continuebtnclicked}"></button>              </stacklayout>       </contentpage.content> </contentpage>

here viewmodel:

 public class localaccountviewmodel : inotifypropertychanged         {                 public localaccountviewmodel()             {                 this.continuebtnclicked = new command(gotopage2);             }               public void gotopage2()             {                  /////              }               public icommand continuebtnclicked             {                  protected set;                 get;             }             public event propertychangedeventhandler propertychanged;           protected virtual void onpropertychanges([callermembername] string propertyname = null)         {             propertychanged?.invoke(this, new propertychangedeventargs(propertyname));         }          }

one way can pass navigation through vm constructor. since pages inherit visualelement, directly inherit navigation property.

code behind file:

public class signin : contentpage {     public signin(){        initializecomponent();        // note vm constructor takes inavigation parameter        bindingcontext = new localaccountviewmodel(navigation);     } }

then in vm, add inavigation property , change constructor accept inavigation. can use property navigation:

public class localaccountviewmodel : inotifypropertychanged {         public inavigation navigation { get; set;}           public localaccountviewmodel(inavigation navigation)         {             this.navigation = navigation;             this.continuebtnclicked = new command(async () => await gotopage2());         }           public async task gotopage2()         {              /////              await navigation.pushasync(new page2());         }           ...

note issue code should fix: gotopage2() method must set async , return task type. in addition, command perform asynchronous action call. because must page navigation asychronously!

hope helps!


Comments

Post a Comment

Popular posts from this blog

inversion of control - Autofac named registration constructor injection -

does autofac support specifying registration name in components' constructors? example: ninject's namedattribute . you need use autofac.extras.attributed package on top achieve this so let's have 1 interface , 2 classes: public interface ihello { string sayhello(); } public class englishhello : ihello { public string sayhello() { return "hello"; } } public class frenchhello : ihello { public string sayhello() { return "bonjour"; } } then have consumer class, in want select instance injected: public class helloconsumer { private readonly ihello helloservice; public helloconsumer([withkey("en")] ihello helloservice) { if (helloservice == null) { throw new argumentnullexception("helloservice"); } this.helloservice = helloservice; } public string sayhello() { return this.helloservice.sayhello()...
Read more

verilog - Systemverilog dynamic casting issues -

i've code snippet following in testbench function void write_to_port( my_data_type_base data ); my_data_type_extended data_ext; if(!$cast(data_ext, data)); `uvm_error(get_type_name(), "failed cast"); `uvm_info(get_name(), $psprintf("data_ext :\n%s", data_ext.sprint()), uvm_medium) // write data_ext out port.... endfunction when run it, i'm getting uvm_error "failed cast." i'm not quire sure why $cast not returning 1. can see, i'm printing out extended class data item after casting uvm_info. can see it's being cast properly. if don't use $cast if condition, don't runtime error. isn't coding practice use if dynamic cast check if $cast returning 1 ? what might reason behind cast not returning 1 in above case? i think semicolon on line 'if' not belong? i think consumes if statement, , uvm_error executes regardless of how if evaluates: if(!$cast(data_ext, data)); <- no semico...
Read more

ios - Change Storyboard View using Seague -

i have following code checks connection server, , depending on want change views if no connection found. nsstring *connect = [nsstring stringwithcontentsofurl:[nsurl urlwithstring:@"http://myserver.com"] encoding:nsutf8stringencoding error:nil]; if (connect == null) { [self performseguewithidentifier:@"network_failure" sender:self]; } else { // other code here } my problem not change views. have added storyboard segue between 2 views identifier of network_failure . not have navigation controller or that, problem? thanks help! no not problem. first of all, in objectivec exists nil object oriented null . must use that. so: if(connect == nil) or better: if(!connect) so due fact nil not same of null , probably code does't enter in if scope . you have been able discover breakpoint. anyway: be sure set trigger segue (line) 2 view controller , , name network_failure (that not best name. should instead view1toview2 ) as, m...
Read more