Wordpress checkbox and Illegal string offset

Question

I'm using the following code to determine if a checkbox has been ticked and then display some text if it has/hasn't as a test.

When its checked, it works fine and the text displays.

When its unchecked I get the message below on the two lines I have commented in my code below.

Illegal string offset 'chec_checkbox_field_0'

<?php

function webdev_init() {
?>
    <h1>Title</h1>
    <h2>WedDev Overlay Plugin Options</h2>
    <form action='options.php' method='post'>
    <h2>Checking</h2>

    <?php
    settings_fields( 'my_option' );
    do_settings_sections( 'checking' );
    submit_button();
    ?>

    </form>
<?php
}

function chec_settings_init() {

    register_setting( 'my_option', 'chec_settings' );

    add_settings_section(
        'chec_checking_section',
        __( 'Your section description', 'wp' ),
        'chec_settings_section_callback',
        'checking'
    );

    add_settings_field(
        'chec_checkbox_field_0',
        __( 'Settings field description', 'wp' ),
        'chec_checkbox_field_0_render',
        'checking',
        'chec_checking_section'
    );
}

function chec_settings_section_callback() {

    echo __( 'This section description', 'wp' );

}

function chec_checkbox_field_0_render() {

    $options = get_option( 'chec_settings' );
?>

//Error message on line bellow
<input type='checkbox' name='chec_settings[chec_checkbox_field_0]' value='1' <?php if ( 1 == $options['chec_checkbox_field_0'] ) echo 'checked="checked"'; ?> />

<?php
}

$options = get_option( 'chec_settings' );
//Error message on line bellow
if ( $options['chec_checkbox_field_0'] == '1' ) {
    echo 'Checked';
} else {
    echo 'Unchecked';
}

Answer 1

$options = get_option( 'chec_settings' );
//Error message on line bellow
if ( is_array( $options ) && $options['chec_checkbox_field_0'] == '1' ) {
    echo 'Checked';
} else {
    echo 'Unchecked';
}

if the value is not checked it will not save in db. So check if the $options is array.

Answer 2

You need to check for the existance of the key, before using it in a condition.

Change:

<?php if ( 1 == $options['chec_checkbox_field_0'] ) echo 'checked="checked"'; ?>

...to:

<?php if (isset($options['chec_checkbox_field_0']) && (1 == $options['chec_checkbox_field_0'])) echo 'checked="checked"'; ?>

This way, if the checkbox is unchecked and / or the option isn't actually set, the first condition will fail, and PHP will immediately disregard the rest of the statement.