API
variant

variant

import { variant } from '@effector/reflect';
const Components = variant({
  source: $typeSelector,
  bind: Props,
  cases: ComponentVariants,
  default: DefaultVariant,
  hooks: Hooks,
});

Method allows to change component based on value in $typeSelector. Optional bind allow to pass props bound to stores or events.

Arguments

  1. source — Store of string value. Used to select variant of component to render and bound props to.
  2. bind — Optional object of stores, events, and static values that would be bound as props.
  3. cases — Object of components, key will be used to match
  4. default — Optional component, that would be used if no matched in cases
  5. hooks — Optional object { mounted, unmounted } to handle when component is mounted or unmounted.
  6. useUnitConfig - Optional configuration object, which is passed directly to the second argument of useUnit from effector-react.

Example

When Field is rendered it checks for $fieldType value, selects the appropriate component from cases and bound props to it.

import { variant } from '@effector/reflect';
import { DateSelector, Range, TextInput } from '@org/ui-lib';
import { createEvent, createStore } from 'effector';
import React from 'react';
 
const $fieldType = createStore<'date' | 'number' | 'string'>('string');
 
const valueChanged = createEvent<string>();
const $value = createStore('');
 
const Field = variant({
  source: $fieldType,
  bind: { onChange: valueChanged, value: $value },
  cases: {
    date: DateSelector,
    number: Range,
  },
  default: TextInput,
});

Shorthand for boolean cases

When you have only two cases, you can use variant shorthand.

const Component = variant({
  if: $isError,
  then: ErrorComponent,
  else: SuccessComponent,
});

This is equivalent to

const Component = variant({
  source: $isError.map((isError) => (isError ? 'error' : 'success')),
  cases: {
    error: ErrorComponent,
    success: SuccessComponent,
  },
});

This shorthand supports bind and hooks fields as well.

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