Formik（というかYup）でemailがユニークかどうかとかpasswordが一致するかなどを検証する

ReactでFormik + Yupを使う最低限（reactstrapを添えて）

formik step by step (React Native)

• string.required
• string.length
• string.min
• string.max
• string.matches
• string.email
• string.url
• string.ensure
• string.trim
• string.lowercase
• string.uppercase

• number.min
• number.max
• number.lessThan
• number.moreThan
• number.positive
• number.negative
• number.integer
• number.truncate
• number.round

• date.min
• date.max

• array.of
• array.required
• array.min
• array.max
• array.ensure
• array.compact

• object.shape
• object.from
• object.noUnknown
• object.camelCase
• object.constantCase

• yup.reach
• yup.addMethod
• yup.ref
• yup.lazy
• ValidationError

• .clone(): Schema
• .label(label: string): Schema
• .meta(metadata: object): Schema
• .describe(): SchemaDescription
• .concat(schema: Schema)
• .validate(value: any, options?: object): Promise<any, ValidationError>
• .validateSync(value: any, options?: object): any
• .validateAt(path: string, value: any, options?: object): Promise<any, ValidationError>
• .validateSyncAt(path: string, value: any, options?: object): any
• .isValid(value: any, options?: object): Promise
• .isValidSync(value: any, options?: object): boolean
• .cast(value: any, options = {}): any
• .isType(value: any): boolean
• .strict(isStrict: boolean = false): Schema
• .strip(stripField: boolean = true): Schema
• .withMutation(builder: (current: Schema) => void): void
• .default(value: any): Schema
• .default(): Any
• .nullable(isNullable: boolean = true): Schema
• .required(message?: string | function): Schema
• .notRequired(): Schema
• .typeError(message: string): Schema
• .oneOf(arrayOfValues: Array, message?: string | function): Schema - Alias: equals
• .notOneOf(arrayOfValues: Array, message?: string | function)
• .when(keys: string | Array, builder: object | (value, schema) => Schema): Schema
• .test(name: string, message: string | function, test: function): Schema
• .test(options: object): Schema
• .transform((currentValue: any, originalValue: any) => any): Schema