Form validation with react and material-ui

Question

I am currently trying to add validation to a form that is built using material-ui components. I have it working but the problem is that the way I am currently doing it the validation function is currently being called on every state change in the input (i.e. every letter that is typed). However, I only want my validation to occur once the typing has stopped.

Given my current code:

class Form extends React.Component {

    state = {open: false, email: '', password: '', email_error_text: null, password_error_text: null, disabled: true};

    handleTouchTap() {
        this.setState({
            open: true,
        });
    }

    isDisabled() {
        let emailIsValid = false;
        let passwordIsValid = false;

        if (this.state.email === "") {
            this.setState({
                email_error_text: null
            });
        } else {
            if (validateEmail(this.state.email)) {
                emailIsValid = true
                this.setState({
                    email_error_text: null
                });
            } else {
                this.setState({
                    email_error_text: "Sorry, this is not a valid email"
                });
            }
        }

        if (this.state.password === "" || !this.state.password) {
            this.setState({
                password_error_text: null
            });
        } else {
            if (this.state.password.length >= 6) {
                passwordIsValid = true;
                this.setState({
                    password_error_text: null
                });
            } else {
                this.setState({
                    password_error_text: "Your password must be at least 6 characters"
                });
            }
        }

        if (emailIsValid && passwordIsValid) {
            this.setState({
                disabled: false
            });
        }
    }

    changeValue(e, type) {
        const value = e.target.value;
        const nextState = {};
        nextState[type] = value;
        this.setState(nextState, () => {
            this.isDisabled()
        });
    }

    login() {
        createUser(this.state.email, this.state.password);
        this.setState({
            open: false
        });
    }

    render() {

        let {open, email, password, email_error_text, password_error_text, disabled} = this.state;

        const standardActions = (
            <FlatButton
                containerElement={<Link to="/portal" />}
                disabled={this.state.disabled}
                label="Submit"
                onClick={this.login.bind(this)} 
            />
        );

        return (
            <div style={styles.container}>
                <Dialog
                    open={this.state.open}
                    title="Enter Your Details to Login"
                    actions={standardActions}
                >
                    <span className="hint--right hint--bounce" data-hint="Enter in your email address">
                        <TextField
                            hintText="Email"
                            floatingLabelText="Email"
                            type="email"
                            errorText={this.state.email_error_text}
                            onChange={e => this.changeValue(e, 'email')} 
                        />
                    </span>
                    <br />
                    <span className="hint--right hint--bounce" data-hint="Enter your password">
                        <TextField
                            hintText="Password"
                            floatingLabelText="Password"
                            type="password"
                            errorText={this.state.password_error_text}
                            onChange={e => this.changeValue(e, 'password')} 
                        />
                    </span>
                </Dialog>
                <h1>VPT</h1>
                <h2>Project DALI</h2>
                <RaisedButton
                    label="Login"
                    primary={true}
                    onTouchTap={this.handleTouchTap.bind(this)} 
                />
            </div>
        );
    }
}

export default Form;

Is there a way that I can achieve my desired functionality, without making a major change to the code, or does it need to be completely refactored?

Answer 1

Does the check have to happen after a certain delay? A solution that I think would suffice in most situations would be to split your code up a bit. Don't trigger your isDisabled() function in changedValue(). Instead have it run on the onBlur event instead.

Try this:

<TextField
  hintText="Password"
  floatingLabelText="Password"
  type="password"
  errorText={this.state.password_error_text}
  onChange={e => this.changeValue(e, 'password')}
  onBlur={this.isDisabled} 
/>

and then your function becomes:

changeValue(e, type) {
    const value = e.target.value;
    const nextState = {};
    nextState[type] = value;
    this.setState(nextState);
}

Answer 2

Current Material-UI version doesn't use the errorText prop but there is still a way that you can use to display error and apply validation to the TextField in Material-UI.

We use the error(Boolean) property to denote if there is an error or not. Further to display the error text use helperText property of the TextField in the Material-UI, just provide it the error text you want to display.

Do it like:

<TextField
  value={this.state.text}
  onChange={event => this.setState({ text: event.target.value })}
  error={text === ""}
  helperText={text === "" ? 'Empty!' : ' '}
/>

Answer 3

Simplest is to call form.reportValidity(). form can be obtained by calling event.currentTarget.form.