mvvm - Input validation on Windows store app -



mvvm - Input validation on Windows store app -

in windows store app using mvvm have textbox 2 way binding should allow numeric values. proper procedure using mvvm ignore when non numeric key pressed?

the value beingness changed of inotifypropertychanged triggers when textbox loses focus. want instant validation properties. can't find proper simple illustration of this.

why not create attached property contain behavior? this:

class="lang-cs prettyprint-override">public class textboxhelper { public static bool getrestricttonumerical(dependencyobject obj) { homecoming (bool)obj.getvalue(restricttonumericalproperty); } public static void setrestricttonumerical(dependencyobject obj, bool value) { obj.setvalue(restricttonumericalproperty, value); } public static readonly dependencyproperty restricttonumericalproperty = dependencyproperty.registerattached("restricttonumerical", typeof(bool), typeof(textboxhelper), new propertymetadata(false, onrestricttonumericalchanged)); private static void onrestricttonumericalchanged(dependencyobject d, dependencypropertychangedeventargs e) { var tb = d textbox; if (tb == null) return; if ((bool)e.newvalue) tb.keydown += tb_keydown; else tb.keydown -= tb_keydown; } static void tb_keydown(object sender, windows.ui.xaml.input.keyroutedeventargs e) { e.handled = e.key < virtualkey.number0 || e.key > virtualkey.number9; } }

you'd utilize in xaml this:

<page x:class="app4.mainpage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="using:app4" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:ignorable="d"> <grid background="{themeresource applicationpagebackgroundthemebrush}"> <textbox verticalalignment="center" local:textboxhelper.restricttonumerical="true" inputscope="number" /> </grid> </page>

this, in opinion, clean mvvm approach input validations might required do. it's overkill simple question, it's more sophisticated validations.

validation mvvm windows-store-apps

Comments

Post a Comment

Popular posts from this blog

Delphi change the assembly code of a running process -

Delphi change the assembly code of a running process - i'm trying alter address 00741fa5 has push test.009e721c . alter push test.009e71c8 . procedure callback; asm force $9e71c8 end; procedure tform2.btn1click(sender: tobject); var ppid :dword; pprocess : cardinal; begin getwindowthreadprocessid(findwindow(nil,pchar('test')), @ppid); pprocess := openprocess(process_all_access, false, ppid); injectasm(pprocess, $741fa5, 10, integer(@callback), 0); end; here injectasm function (with error checking) function injectasm(process: longword; injectaddress, injectsize, codeaddress, codesize : integer): pointer; var csize, rsize : integer; replaced : array of byte; jmp : array [0..4] of byte; jmpaddress : integer; nopv : byte; : integer; nbr: ulong_ptr; begin //injectsize must equal or greater 5, because need space our //(far) jmp wwxxyyzz instruction //if there's no space, inject in place of few instructions if injectsize ...
Read more

json - Hibernate and Jackson (java.lang.IllegalStateException: Cannot call sendError() after the response has been committed) -

json - Hibernate and Jackson (java.lang.IllegalStateException: Cannot call sendError() after the response has been committed) - hello have problem hibernate , jackson. have 2 pojos @entity @table(name = "users") public class user implements serializable { static final long serialversionuid = 4235637833262722256l; @id @generatedvalue private int id; @column(name = "creation_date") private date creationdate; @column(name = "first_name") private string firstname; @column(name = "last_name") private string lastname; @version @column(name = "version") private int version; @column(name = "e_mail") private string email; @column(name = "enabled") private boolean enabled; @column(name = "login") private string login; @column(name = "password") private string password; @jsonmanagedreference("role") @onetomany(mappedby = "user", cascade = cascadetype.all,fetch = fetchtyp...
Read more

C++ 11 "class" keyword -

C++ 11 "class" keyword - i've started using c++ 11 little bit more , have few questions on special uses of class keyword. know it's used declare class, there's 2 instances have seen don't understand: method<class t>(); and class class_name *var; why precede typename keyword class in first example, , keyword pointer in sec example? that known elaborated type specifier , necessary when class name "shadowed" or "hidden" , need explicit. class t { }; // love of god don't t t; t t2; if compiler smart, give these warnings: main.cpp:15:5: error: must utilize 'class' tag refer type 't' in scope t t2; ^ class main.cpp:14:7: note: class 't' hidden non-type declaration of 't' here t t; ^ if class not defined, deed forwards declaration. for example: template <typename t> void method() { using type = typename t::value_type; } method...
Read more