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January 24, 2020 16:58
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my own useForm hook
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const schema = { | |
email: { | |
presence: { allowEmpty: false, message: "required" }, | |
email: { | |
message: "valid" | |
} | |
} | |
}; | |
interface LoginFormFields { | |
email: string; | |
} | |
const { formState, handleChange, hasError } = useForm<LoginFormFields>(schema, { email: "" }); | |
<TextField | |
name="email" | |
error={hasError("email")} | |
fullWidth | |
helperText={hasError("email") ? t(`form.${formState.errors.email[0]}`) : null} | |
label={t("form.email")} | |
required={true} | |
type="email" | |
value={formState.values.email || ""} | |
onChange={handleChange} | |
disabled={loading} | |
autoFocus | |
/> |
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import { ChangeEvent, useState } from "react"; | |
import validate from "validate.js"; | |
// if you add this validator it will always fail. Useful for custom validations. | |
validate.validators.fail = function(value: string, options: any) { | |
return options.message; | |
}; | |
interface FormStateType { | |
[name: string]: string | boolean; | |
} | |
interface FormStateErrors { | |
[name: string]: string[]; | |
} | |
export interface FormState<T> { | |
isValid: boolean; | |
values: T; | |
touched: FormStateType; | |
errors: FormStateErrors; | |
} | |
export const useForm = <T>(schema: any, values: T) => { | |
const errors = validate(values, schema) || {}; | |
const [formState, setFormState] = useState<FormState<T>>({ | |
isValid: Object.keys(errors).length === 0, | |
values, | |
touched: {} as FormStateType, | |
errors | |
}); | |
const handleChange = (event: ChangeEvent<HTMLInputElement>) => { | |
event.persist(); | |
setFormState(prevFormState => { | |
const newState = { | |
...prevFormState, | |
values: { | |
...prevFormState.values, | |
[event.target.name]: event.target.type === "checkbox" ? event.target.checked : event.target.value | |
}, | |
touched: { | |
...prevFormState.touched, | |
[event.target.name]: true | |
} | |
}; | |
newState.errors = validate(newState.values, schema) || {}; | |
newState.isValid = Object.keys(newState.errors).length === 0; | |
return newState; | |
}); | |
}; | |
const hasError = (field: string) => !!(formState.touched[field] && formState.errors[field]); | |
return { formState, handleChange, hasError }; | |
}; |
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