在带有ng-messages的angularjs材料md-input-container中显示服务器端验证消息

Question

I have a form with some inputs which are in md-input-container. Each input have some validation message with ng-messages directive:

<form name="ctrl.myForm" layout="column" ng-submit="addUser(model)">

    <input hide type="submit" />
    <div layout="column" layout-padding>

        <md-input-container> 
            <label translate>Username</label>
            <input name="username" ng-model="model.username" type="text" required>
            <div ng-messages="ctrl.myForm.username.$error">
                <div ng-message="required" translate>This field is required.</div>
                <div ng-message="unique" translate>Username is used before.</div>
            </div>
        </md-input-container>

        <md-input-container> 
            <label translate>Email</label>
            <input name="email" ng-model="model.email" required>
            <div ng-messages="ctrl.myForm.email.$error">
                <div ng-message="required" translate>This field is required.</div>
                <div ng-message="email" translate>Email is not valid.</div>
            </div>
        </md-input-container>

    </div>

    <div layout="row">
        <span flex></span>
        <md-button 
            class="md-raised"
            ng-click="cancel()">
            <wb-icon>close</wb-icon>
            <span translate>Cancel</span>
        </md-button>
        <md-button 
            class="md-raised"
            ng-click="addUser(model)">
            <wb-icon>done</wb-icon>
            <span translate>Add</span>
        </md-button>
    </div>

</form>

In my controller, I have a function named addUser(model) which send given data to server and receives some validation codes. I set appropriate keys in $error objects but relative messages are not show. I set keys as following if I get error from server:

function addUser(model){
    $myService.newUser(model)//
    .then(function(user) {
        // user is created successfully.
    }, function(error) {
        ctrl.myForm.$invalid = true;
        ctrl.myForm.username.$error['unique'] = true;
        ctrl.myForm.email.$error['email'] = true;
    });
}

I expect when I set keys as true related messages appear in the form but message are not shown. In this time if I change value of a field related message of that field is shown! I could not find problem.

Answer 1

Read here https://docs.angularjs.org/guide/forms about $asyncValidators , there are some examples also. ( ctrl.$asyncValidators.username=... etc.)

In few words:

Angularjs built-in validation requires you to write and add validators. You should not control $invalid, $error fields manually (Thats why they have $ prefix). Angularjs material also follow this approach.

PS reason why lines like ctrl.myForm.$invalid = true; wont work consistently is quite simple - angularjs next validation run will set it back to false