knockout dropdown validation on load? required

问题

There are many post on this one which i find not helpful and i need to find out why and how .

I made a fiddle with two controls dropdown and textbox and applied required validation with .extend My fiddle

Question 1 : when i first load my page i get a validation error beside dropdown but not beside textbox ? i am confused why is that .

Question 2 : Ok . its awkward to display a error message on load so i planned to disable error messages display on load . Added this line ko.validation.init({ insertMessages: false }); . By this i got rid of on load error message display . BUT when i click on submit i can't find the error message text beside textbox or dropdwon .

One way or the other dropdown is failing my cause to display error text.

Any feasible approach is much appreciated .

回答1:

1. If you subscribe to your observables, you will see that country is actually set on load by ko, which is not the case for code (demo):

   self.Code.subscribe(function () { alert("Codes changed"); });
   self.country.subscribe(function () { alert("Country has changed"); });
   

   This is caused by how select is handled (how options binding is handled I believe) and explains why the validation is done on country.

2. insertMessages: false will hide all messages, then you need to handle them with the validationMessage binding.

Simply remove the init value of your observable (demo):

self.Code = ko.observable();
self.country = ko.observable(); // no ""

回答2:

To disable messages on load you need this instruction

self.Errors.showAllMessages(false)

this will disable all message on first load. setting this will not help you

ko.validation.init({ insertMessages: false })

For your first problem, You must be doing this

<select data-bind='blah,validationElement:TextBoxField' >

this will cause it. Hope it helps.

回答3:

Using this is perfect:

ko.validation.group(yourViewModel, { deep: true }).showAllMessages(false);

However it must be done after calling applyBindings:

ko.applyBindings(yourViewModel);

Otherwise it doesn't work.

来源：https://stackoverflow.com/questions/25422260/knockout-dropdown-validation-on-load-required