Don't evaluate variable in view - angularjs

I have a site built with AngularJS. I need to put a text somewhere on the page that looks something like this: Use {{name}} to display the username.
But AngularJS automatically tries to evaluate {{name}}. But in this case I don't want it to be evaluated. I just simply want to show that as a text.
I already tried to use the unicode characters: {{name}}. But it still evaluates that...
Is there a way to do this?

Use the ngNonBindable directive
<span ng-non-bindable>Use {{name}} to display the username.</span>

Related

angular-translate: unable to use dynamic data in nested directives

I'm using angular-translate package. It provides developers with different things. One thing is internal interpolation so you are able to use dynamic data inside translation strings. Or even angular directives.
Assume we have greeting.
'Hello {{name}}!'
That is used in template like that:
<h3 translate="greeting" translate-values="vm.user" translate-compile></h3>
But user.name maybe empty. In this case I'd like to see "Hello anonymous!". I'm trying to use ng-if but it does not work in expected way:
'greeting': 'Hello <span ng-if="!name">anonymous</span>{{name}}!'
It will output "Hello anonymousJack!" like if name is empty and is not empty at the same time.
Why I don't want to inject ng-if into template instead of translation? Because depending on language there will be different position of name part. So I'd like to avoid unclear decomposition like
<span translate="greeting_1"></span>
<span ng-if="vm.user.name" bind="vm.user.name"></span>
<span ng-if="!vm.user.name" translate="greeting_anomymous"></span>
<span translate="greeting_2"></span>
This looks unclear and confusing. Especially in more complex cases.
I've found all data passed through translate-values is available in nested variable interpolateParams. So next will work:
'greeting': 'Hello <span ng-if="!interpolateParams.name">anonymous</span>{{name}}!'

How to interpolate expressions in ng-messages directive?

Let's say that I have a form name "signupForm". When I use the ng-disabled directive on a button (to disable the form in case its invalid), I use
ng-disabled="{{formName}}.$invalid"> (formName contains the value signupForm)
When I inspect the button in browser, the above directive evaluates to ng-disabled="signupForm.$invalid">. This is perfect. The problem is that when I try to use the same expression inside of the ng-messages directive, like: ng-messages ="{{formName}}.$error"> the expression is NOT interpolated. So if I use the directive on a div and inspect it in browser, I see it as:
<div ng-messages="{{formName}}.$error"></div> whereas I expect it to be shown as <div ng-messages="signupForm.$error"></div>. But this does not happen.
So what can be done to make the ng-messages directive interpolate the expression & show it correctly? I have tested this issue with AngularJS 1.4.7 & 1.5.0-rc.1 and the issue exists in both of them. Any help is appreciated. Thank you.
ng-messages=this[formName].$error
ng-messages doest not allow interpolation in attribute value.
but we can pass expression to be evaluated.
this in html represent current scope and it has all the information about form with validations too. you can log it and see yourself.
ng-messages="this[formName][fieldName].$error"
ng-messages="this[formName].$error"
will work, worked for me

when should I write code with `{{}}` and without `{{}}` in html of angular js project

May be This is a simple question but it is challenging for me.
In angularJS when i write {{}} in html code so i write code like this like
if i talk about dynamic id, we write like code this
<div ng-repeat = 'item in itmes track by $index'>
<div id = "div-{{$index}}">{{item.name}}</div>
</div>
If i use any model without {{}} i write this example
<input id = 'name' ng-model = "item.name"/>
whenever i am coding in angular js, i write code without {{}} then if it is not work then i try code with {{}} and vise versa. and randomly 1 will correct
Question is when i write code with {{}} and without {{}} in html code ?
After the OP explained what exactly was the problem.
So, the question here is very simple: when do we use {{}} and when we don't in the context of ng-model.
When you do a <input type=... ng-model="someModel>, what you're essentially telling Angular is: "Here is an input element; attach $scope's someModel variable to the value of this input element.
Now, you can use this in your JavaScript controller like so: $scope.someModel, but what about HTML? We have a templating language in Angular, and when you give it some variable (say someModel), it'll search its $scope for it, and then put in the value there. If it is unable to, it'll throw a nasty error.
In essence, {{}} GETS the value, without that, you generally set the variable to gold the value of something.
Very simply put, AngularJS thinks that the content within the brace is an expression, which must be resolved. Once it is, Angular puts the value of the resolved expression there. In the most basic of the terms, you just tell it: "Here is some expression; put the evaluated value instead."
In ES6, we call it template strings.
So, you'll use it for expressions which mutate after every iteration. Say, a loop or something. Places where you know what the answer is, or you have static content, you won't use it.
Say you have the following bit of code:
...
...
$scope.figureOne = 10;
in your controller.js and the following in its view file:
<div>My age is {{ figureOne }}</div>
Angular gets the value from the $scope, and puts it there; so, the rendered form will be: My age is 10. However, if you had the following
<div>My age is figureOne</div>
This time, Angular knows that there is nothing to evaluate or resolve, so, it'll just render it as it is: My age is figureOne.
I hope I made it clear! :)
Angular directives have different types of parameters. Some parameters (#) expect string values and some expect javascript expressions (=) (with variables bound to $scope).
There's no obvious way to know which parameter expects what type of value (aside from looking at documentation).
If a variable expects static string value and you have an angular expression
then you'll need to evaluate it by wrapping in {{}}
If there variable expects an expression and you have an expression
simply type that in.
It's the best to avoid using {{}} where possible, your dynamic ID will fail when Angular hasn't interpolated the expression yet, use ng-attr-id="div-{{$index}} for that. https://docs.angularjs.org/guide/directive#-ngattr-attribute-bindings
Another example, if you have a slow connection and Angular isn't loaded yet users will see the {{}}, you can avoid this by using ng-bind="".
See this thread for more info: AngularJS : Why ng-bind is better than {{}} in angular?
It is very simple.
{{something}} - used for one way binding(Static).
<input type="text" value="{{something}}">
Now if you change its value in HTML ,you can not get it by $scope.something in js.
but If you use ng-model="something",you can get its value in JS.
This happens because ng-model is two way binding.
<input type="text" ng-model="something">
Mostly We use ng-model for forms and {{}} to display static information like User details or else.

Generate dynamic expressions in ng-repeat

I have a ngRepeat element that has a delete button that triggers a confirmation message. I'm trying to make the confirmation message show with a dynamic expression like so:
<div ng-repeat="item in items">
<a ng-click="delete(item_id)"></a>
<span ng-show="{{item._id}}_delete">Are you sure you want to delete your review? </span>
</div>
I'm not sure if this is the right way to create dynamic expressions, but this is the only way I can get the expression to at least generate in html.
But I am getting this error for all the repeated items (with different item ids in each error):
Error: [$parse:syntax] Syntax Error: Token 'cb0a2a73ede6e3a9d7a58_delete' is an unexpected token at column 4 of the expression [543cb0a2a73ede6e3a9d7a58_delete] starting at [cb0a2a73ede6e3a9d7a58_delete].
^ the outputted item._id for that item is 543cb0a2a73ede6e3a9d7a58 for example.
Angular is expecting an expression there that returns true or false for ng-show. So just rendering a String won't really help. You could either define a controller function that resolves to true or false or just write the expression inline, like ng-show="item.id === 2".
But it seems that you want a confirmation dialog before deleting, in that case you should write a custom directive that intercepts the click action before executing it (unfortunately there is no such thing as ng-confirm in Angular built-in).
Here is an example of such a directive: https://gist.github.com/asafge/7430497
If you simply want to toggle a message to the user, you could simply make your span dependant on a scope variable that gets toggled, like so:
<a ng-click="delete(item_id); showDelete=!showDelete">item</a>
<span ng-show="showDelete">Are you sure you want to delete your review? </span>
JSFiddle here.
However, you probably want to wrap it all up into a directive like #frank blizzard mentioned.
try this one :)
AH, if item._id starts with a number it will get a error
Variable names must begin with a letter
link
so ng-show bound to a variable in the scope and it is dynamically creating. a_delete,b_delete will work fine but if it generate like 1_delete,2_delete it will result a error because those are starts with a number.
In your case item._id starts with number like 543cb0a2a73ede6e3a9d7a58 as you mentioned in you question. so ng-show ends with something like ng-show="543cb0a2a73ede6e3a9d7a58_delete". That should get a error because of violation of naming-conventions.

Angular interpolation expression not evaluated

I am having an issue with Angular interpolation.
I have a directive template that looks like this:
<div class="autocomplete {{attrs.class}}" id="{{attrs.id}}">
<input type="text" {{attrs.autofocus | toAutofocusText}} ng-model="searchParam" placeholder="{{attrs.placeholder}}"/>
...
</div>
The problem I have is that this expression is not evaluated:
{{attrs.autofocus | toAutofocusText}}
However, if I change this to something like this:
x="{{attrs.autofocus | toAutofocusText}}"
It does get evaluated.
Could someone explain me why this would be happening? I am guessing it is something fairly fundamental, but I can't find anything on Google.
So the answer is that attributes don't get interpolated on that level. Or to be more specific, at the time when your HTML is compiled, angular processes DomElements. A Dom element with an attribute that starts with {{ isn't a valid attribute, which is why the $compile don't know about it. However, it does now about such expressions within attribute values, or Dom element contents.
Remember that angular is (they say) what html would be if written for applications. The data binding syntax is evaluated as html. Saying:
x="{{attrs.autofocus | toAutofocusText}}"
is different because now you are talking about an attribute's property being evaluated not some unknown characters inside an html element.
Another thing I would recommend is you look into using ng-class for manipulating the class stuff:
http://docs.angularjs.org/api/ng/directive/ngClass

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