Reputation: 268
My Component has form input fields. These made use of a useState hook with their value and setValue for each input field. I want to optimize my component so the input fields made use of the same custom Hook which I called useFormInput
Inspired by Dan Abramov https://youtu.be/dpw9EHDh2bM see at 49:42
This works perfectly. However now I want to update the username after a new exercise is created. This is in the onSubmit method. But I'm not sure how to do this. Before I refactored I could use setUserName(), but now username is set by the generic custom hook function useFormInput
the username has an onChange method, so I thought I can maybe use this. However this uses the e.target.value because it is used for an input field.
Component: I commented out the setUserName(''), here I want to update the username
const CreateExercise = () => {
const inputEl = useRef(null)
const username = useFormInput('')
const description = useFormInput('')
const duration = useFormInput(0)
const date = useFormInput(new Date())
const [users, setUsers] = useState([])
useEffect(() => {
axios
.get('http://localhost:5000/users/')
.then(res => {
if (res.data.length > 0) {
setUsers(res.data.map(user => user.username))
}
})
.catch(err => console.log(err))
}, [])
const onSubmit = e => {
e.preventDefault()
const exercise = {
username: username.value,
description: description.value,
duration: duration.value,
date: date.value
}
axios
.post('http://localhost:5000/exercises/add', exercise)
.then(res => console.log(res.data))
debugger
// setUsername('')
window.location = '/'
}
custom Hook useFormInput:
const useFormInput = initialValue => {
const [value, setValue] = useState(initialValue)
const handleChange = e => {
const newValue = e.target ? e.target.value : e
setValue(newValue)
}
return {
value,
onChange: handleChange
}
}
I expect the value in the state of username is updated to an empty string ' '
Complete code is on my repo on https://github.com/jeltehomminga/mern-tracker
Upvotes: 1
Views: 10787
Reputation: 19762
Instead of trying to maintain more than 1 state, I'd recommend combining all state into one object. Then you can move everything into your custom hook. In addition, always make sure you handle and communicate any errors to the user.
Working example:
hooks/useFormHandler (the API
defined below is an object with functions to mimic API calls -- you'll replace this with real API calls. Also, if you wanted to make this hook reusable for other form
components, then you'll need to remove the useEffect
and handleSubmit
functions from the custom hook and place them inside the specified functional component instead)
import { useCallback, useEffect, useState } from "react";
import API from "../../API";
// create a custom useFormHandler hook that returns initial values,
// a handleChange function to update the field values and a handleSubmit
// function to handle form submissions.
const useFormHandler = initialState => {
const [values, setValues] = useState(initialState);
// on initial load this will attempt to fetch users and set them to state
// otherwise, if it fails, it'll set an error to state.
useEffect(() => {
API.get("http://localhost:5000/users/")
.then(res => {
if (res.data.length > 0) {
setValues(prevState => ({
...prevState,
users: res.data.map(({ username }) => username)
}));
} else {
setValues(prevState => ({
...prevState,
error: "Unable to locate users."
}));
}
})
.catch(err =>
setValues(prevState => ({ ...prevState, error: err.toString() }))
);
}, []);
// the handleChange function will first deconstruct e.target.name and
// e.target.value, then in the setValues callback function, it'll
// spread out any previous state before updating the changed field via
// [name] (e.target.name) and updating it with "value" (e.target.value)
const handleChange = useCallback(
({ target: { name, value } }) =>
setValues(prevState => ({ ...prevState, error: "", [name]: value })),
[]
);
// the handleSubmit function will send a request to the API, if it
// succeeds, it'll print a message and reset the form values, otherwise,
// if it fails, it'll set an error to state.
const handleSubmit = useCallback(
e => {
e.preventDefault();
const exercise = {
username: values.username,
description: values.description,
duration: values.duration,
date: values.date
};
// if any fields are empty, display an error
const emptyFields = Object.keys(exercise).some(field => !values[field]);
if (emptyFields) {
setValues(prevState => ({
...prevState,
error: "Please fill out all fields!"
}));
return;
}
API.post("http://localhost:5000/exercises/add", exercise)
.then(res => {
alert(JSON.stringify(res.message, null, 4));
setValues(prevState => ({ ...prevState, ...initialState }));
})
.catch(err =>
setValues(prevState => ({ ...prevState, error: err.toString() }))
);
},
[initialState, setValues, values]
);
return {
handleChange,
handleSubmit,
values
};
};
export default useFormHandler;
components/CreateExerciseForm
import isEmpty from "lodash/isEmpty";
import React, { Fragment } from "react";
import { FaCalendarPlus } from "react-icons/fa";
import Spinner from "react-spinkit";
import Button from "../Button";
import Input from "../Input";
import Select from "../Select";
import useFormHandler from "../../hooks/useFormHandler";
const fields = [
{ type: "text", name: "description", placeholder: "Exercise Description" },
{ type: "number", name: "duration", placeholder: "Duration (in minutes)" },
{
type: "date",
name: "date",
placeholder: "Date"
}
];
// utilize the custom useFormHandler hook within a functional component and
// pass it an object with some initial state.
const CreateExerciseForm = () => {
const { values, handleChange, handleSubmit } = useFormHandler({
username: "",
description: "",
duration: "",
date: "",
error: ""
});
// the below will show a spinner if "values.users" hasn't been fulfilled yet
// else, it'll show the form fields. in addition, if there's ever a
// "values.error", it'll be displayed to the user.
return (
<form
style={{ width: 500, margin: "0 auto", textAlign: "center" }}
onSubmit={handleSubmit}
>
{isEmpty(values.users) ? (
<Spinner name="line-scale" />
) : (
<Fragment>
<Select
name="username"
placeholder="Select a user..."
handleChange={handleChange}
value={values.username}
selectOptions={values.users}
style={{ width: "100%" }}
/>
{fields.map(({ name, type, placeholder }) => (
<Input
key={name}
type={type}
name={name}
placeholder={placeholder}
onChange={handleChange}
value={values[name]}
/>
))}
<Button type="submit">
<FaCalendarPlus style={{ position: "relative", top: 2 }} />
Create Exercise
</Button>
</Fragment>
)}
{values.error && <p>{values.error}</p>}
</form>
);
};
export default CreateExerciseForm;
Or, if you insist on using separated states, then create a resetValue
function in the useFormInput
hook:
const useFormInput = initialValue => {
// initialize state from "initialValue"
const [value, setValue] = useState(initialValue)
// handle changes to the "value" state via updating it
// with e.target.value
const handleChange = useCallback(({ target: { value } => {
setValue(value)
}, []);
// reset the value back to initialValue
const resetValue = useCallback(() => {
setValue(initialValue);
}, []);
return {
value,
handleChange,
resetValue
}
}
Then, destructure properties for the username (and other states, if needed):
const CreateExercise = () => {
// use ES6 destructure and aliasing to extract and rename the
// "value" (as username), "handleChange" function (as
// handleUsernameChange) and "resetValue" function (as resetUsername)
const {
value: username,
handleChange: handleUsernameChange,
resetValue: resetUsername
} = useFormInput('')
...other form state
...useEffect(() => {}, [])
const handleSubmit = useCallback(e => {
e.preventDefault();
const exercise = {
username: username,
description: description,
duration: duration,
date: date
};
axios
.post('http://localhost:5000/exercises/add', exercise)
.then(res => {
console.log(res.data)
// only reset the username if the exercise was successfully
// created
resetUsername();
})
.catch(err => console.log(err.toString());
}, [date, description, duration, resetUsername, username]);
return ( ...form )
}
Upvotes: 5
Reputation: 968
I took a look and did a PR - Formik implementation w/validation.
Here is the PR - https://github.com/jeltehomminga/mern-tracker/pull/1
<>
<h3>Create New Exercise Log</h3>
<pre>{JSON.stringify({ formData }, null, 2)}</pre>
<ExerciseForm {...{ users }} onChange={data => setFormData(data)} />
</>
import React from "react";
import * as Yup from "yup";
import { Formik, Form, Field } from "formik";
import DatePicker from "react-datepicker";
import cx from "classnames";
const requiredMessage = "Required";
const exerciseFormSchema = Yup.object().shape({
username: Yup.string().required(requiredMessage),
description: Yup.string()
.min(2, "Too Short!")
.required(requiredMessage),
duration: Yup.number()
.integer()
.min(1, "Min minutes!")
.max(60, "Max minutes!")
.required(requiredMessage),
date: Yup.string().required(requiredMessage)
});
const ExerciseForm = ({ users = [], onChange }) => {
return (
<Formik
initialValues={{
username: "",
description: "",
duration: "",
date: ""
}}
validationSchema={exerciseFormSchema}
onSubmit={values => onChange(values)}
>
{({
values,
touched,
errors,
handleChange,
handleBlur,
isSubmitting,
setFieldValue
}) => {
const getProps = name => ({
name,
value: values[name],
onChange: handleChange,
onBlur: handleBlur,
className: cx("form-control", {
"is-invalid": errors[name]
})
});
return isSubmitting ? (
// Replace this with whatever you want...
<p>Thanks for the Exercise!</p>
) : (
<Form>
<FormControl label="Username">
<>
<select {...getProps("username")}>
<>
<option value="default">Select user...</option>
{users.map(person => (
<option key={person} value={person.toLowerCase()}>
{person}
</option>
))}
</>
</select>
<FormErrorMessage {...{ errors }} name="username" />
</>
</FormControl>
<FormControl label="Description">
<>
<Field {...getProps("description")} />
<FormErrorMessage {...{ errors }} name="description" />
</>
</FormControl>
<FormControl label="Duration in minutes">
<>
<Field {...getProps("duration")} type="number" />
<FormErrorMessage {...{ errors }} name="duration" />
</>
</FormControl>
<FormControl label="Date">
<>
{/* Was present before refactor */}
<div>
<DatePicker
{...getProps("date")}
selected={values.date}
minDate={new Date()}
onChange={date => setFieldValue("date", date)}
/>
<FormErrorMessage {...{ errors }} name="date" />
</div>
</>
</FormControl>
<button type="submit" className="btn btn-primary">
Create Exercise log
</button>
</Form>
);
}}
</Formik>
);
};
export default ExerciseForm;
// Created to manage label and parent className
const FormControl = ({ label, children }) => (
<div className="form-group">
<label>{label}:</label>
{children}
</div>
);
const FormErrorMessage = ({ name, errors }) => {
const error = errors && errors[name];
return error ? (
<div
class="invalid-feedback"
// Add inline style override as error message cannot sit as sibling to datePicker (bootstrap css)
style={{ display: "block" }}
>
{error}
</div>
) : null;
};
Upvotes: 0