How to make input read only based on particular value in Vue?

You can do something like this:

<input v-bind:readonly="isReadOnly">

Please note that, according to HTML specs, the select tag in HTML doesn't have a readonly attribute.

However, in general case, I'd go with something like this:

<input class="form-control" id="selectCategory" :readonly="cat_id >= 1">

Basically, the documentation says that if an attribute value evaluates to false, then the attribute being omitted. See here for further details.

you could have a computed property that returns a boolean dependent on whatever criteria you need.

<input type="text" :disabled=isDisabled>

then put your logic in a computed property...

computed: {
 isDisabled() {
// evaluate whatever you need to determine disabled here...
   return true;
 }
}

JSFIDDLE https://jsfiddle.net/sureshamk/0dzvcf4d/1320/

I ran into this issue while making a form for a password changing form and I encountered the browser trying to autocomplete everything. This should prevent the autocomplete from firing and also provide a method to change the value to suit your needs.
For some reason adding a v-bind:readonly property of true reverts to readonly="readonly"
Here is my currently working example which removes and re-adds the readonly property on focusout.

Vue Template HTML

<input type="password" v-model="user.password" placeholder="Password" @focusin="toggleReadonly" @focusout="toggleReadonly" :readonly="true">

Method

toggleReadonly(event){
          event.preventDefault()
          if(event.target.getAttribute('readonly') == 'readonly'){
              event.target.removeAttribute('readonly')
          }
          else{
              event.target.setAttribute('readonly', 'readonly')
         }
 }