# Customizing classes

Article

Using Tailwind with Vue Formulate 2.4

Using the newly customizable classes in Vue Formulate, learn how to leverage the Tailwind CSS utility framework to quickly add custom styling to your forms.

There are 4 ways to change the classes applied to DOM elements inside a FormulateInput:

  1. Use props on a FormulateInput.
  2. Globally via the classes option.
  3. Globally via the baseClasses option.
  4. Manually override the DOM using slots.

In the first two cases, you can use a string, array, or function to define which classes should be applied to a given element (e.g., label) in a given state (e.g., field has validation errors). Each element and state is identified by class key.

# Changing classes with props

Changing classes on a given input is easy. Simply target the class key you’d like to change with a prop named [element class key]-class. To target a state use [element class key]-[state class key]-class.

# Strings (to replace base classes)

Use string values in your class prop to replace any base classes.

<FormulateInput
  label="The label is using its own class"
  label-class="my-label-class"
/>
<!-- <label class="my-label-class"> -->

# Arrays (to append to base classes)

To append classes to the base classes, use an array in your class prop.

<FormulateInput
  label="The input wrapping div is using its own class"
  :wrapper-class="['my-wrapper-class']"
/>
<!-- <div class="formulate-input-wrapper my-wrapper-class" /> -->

# Functions

For fine grained control you can use a function. The function will receive 2 arguments, a class context object and an array of base classes generated using the global options.

<FormulateInput
  label="The element div is using its own class"
  :element-class="(context, classes) => ['my-element-class'].concat(classes)"
/>
<!-- <div class="my-element-class formulate-input-element formulate-input-element--text" /> -->

# Changing classes globally

To globally update which classes are applied to every FormulateInput by default you can update the classes option with an object of class keys.

Similar to modifying classes with props the values in the classes option can be a string, array, or function. Strings overwrite any base classes, arrays are appended to the base classes, and functions allow for fine grained control and can accept a context and baseClasses arguments respectively.

# String

import Vue from 'vue'
import VueFormulate from 'vue-formulate'

Vue.use(VueFormulate, {
  classes: {
    outer: 'mytheme-wrapper',
  }
})
// All <FormulateInput> will output:
// <div class="mytheme-wrapper">...

# Array

...
Vue.use(VueFormulate, {
  classes: {
    outer: ['mytheme-wrapper'],
  }
})
// All <FormulateInput> will output:
// <div class="formulate-input mytheme-wrapper">...

# Function

...
Vue.use(VueFormulate, {
  classes: {
    outer: (context, classes) => {
      return classes.concat([
        'mytheme-wrapper',
        `mytheme-wrapper--${context.type}`
      ])
    },
  }
})
// All <FormulateInput> will output:
// <div class="formulate-input mytheme-wrapper mytheme-wrapper--[type]">...

# A custom baseClasses function

For advanced use cases, you can also choose to override the base classes by setting options.baseClasses to your own function. This function will be applied to every class key on every <FormulateInput>. For example, if you wanted to perform a reset of all classes in Vue Formulate you could return an empty array:

Vue.use(VueFormulate, {
  baseClasses: (baseClasses, context) => []
})

# Class keys

Manipulating classes on DOM elements requires targeting which element you want to add/remove classes on. To allow for precise class targeting, every DOM element is assigned an “element key” which can be used to customize classes.

In addition to “element keys”, Vue Formulate also includes “state keys” that are used to describe a specific state of the input. For example hasErrors is the state key for an input that is currently displaying an error. Classes defined with “state keys” are additive, they do not replace any base classes.

# Element keys

Key Default Description
outer .formulate-input The outermost div wrapper.
wrapper .formulate-input-wrapper A wrapper around the label + interior element.
label .formulate-input-label
.formulate-input-label--[position]
The label wrapper and its position (before/after).
element .formulate-input-element
.formulate-input-element--[type]
The wrapper around the actual <input> element(s).
input n/a Applied directly to the input DOM element. Not used by default to allow for more flexible cascading.
help .formulate-input-help
.formulate-input-help--[position]
Wrapper around the help text.
errors .formulate-input-errors Wrapper around the list of errors.
error .formulate-input-error Wrapper around a single error message.

Chart of element class keys

Some input types have additional class keys that are detailed on their own pages:

# State keys

State keys make it easy to add a class for a given input state like when a field has a value. State keys must always be combined with an element key.

Key Description
hasErrors The field is visibly showing errors. If the error-behavior is not live this will be false until the errors are shown.
hasValue The field has a value.
isValid The field has no errors regardless of the visibility.

Note

You can achieve the same result as a state key by using a function for an element key and appending some values based on state provided in the context. These state keys are a helpful shortcut to the same result.

# Globally

To define a state key globally, combine it camel-case style with an element key.

Vue.use(VueFormulate, {
  classes: {
    labelHasValue: 'has-value'
  }
})

# Via props

To use a state class key via props, you combine it with a element key (kebab case) [element key]-[state-key]-class. For example, to add a check mark to the label of a field that is valid:

<FormulateInput
  label="Social Security Number"
  placeholder="xxx-xx-xxx"
  help="Please enter your social security number: XXX-XX-XXXX"
  value="332-22-9982"
  :validation="[
    ['required'],
    ['matches', /^\d{3}\-\d{2}\-\d{4}$/]
  ]"
  label-is-valid-class="my-valid-class"
/>
Please enter your social security number: XXX-XX-XXXX

# Class context

Global class functions and prop class functions both receive a “class context” with the following values:

Property Description
attrs Attributes that are applied to the input (ex. disabled)
classification The classification of the input (text, group, select, etc.)
hasErrors Boolean indicating visible errors.
hasValue Boolean whether or not the field has a value.
helpPosition String describing the position of the help text. before or after.
isValid Boolean indicating if the field is error free, regardless of error visibility.
labelPosition String describing the position of the label. before or after.
type The type of input.
value The value of the input.