Pretty-Printing JSON with PHP

Solution 1:

PHP 5.4 offers the JSON_PRETTY_PRINT option for use with the json_encode() call.

http://php.net/manual/en/function.json-encode.php

<?php
...
$json_string = json_encode($data, JSON_PRETTY_PRINT);

Solution 2:

This function will take JSON string and indent it very readable. It also should be convergent,

prettyPrint( $json ) === prettyPrint( prettyPrint( $json ) )

Input

{"key1":[1,2,3],"key2":"value"}

Output

{
    "key1": [
        1,
        2,
        3
    ],
    "key2": "value"
}

Code

function prettyPrint( $json )
{
    $result = '';
    $level = 0;
    $in_quotes = false;
    $in_escape = false;
    $ends_line_level = NULL;
    $json_length = strlen( $json );

    for( $i = 0; $i < $json_length; $i++ ) {
        $char = $json[$i];
        $new_line_level = NULL;
        $post = "";
        if( $ends_line_level !== NULL ) {
            $new_line_level = $ends_line_level;
            $ends_line_level = NULL;
        }
        if ( $in_escape ) {
            $in_escape = false;
        } else if( $char === '"' ) {
            $in_quotes = !$in_quotes;
        } else if( ! $in_quotes ) {
            switch( $char ) {
                case '}': case ']':
                    $level--;
                    $ends_line_level = NULL;
                    $new_line_level = $level;
                    break;

                case '{': case '[':
                    $level++;
                case ',':
                    $ends_line_level = $level;
                    break;

                case ':':
                    $post = " ";
                    break;

                case " ": case "\t": case "\n": case "\r":
                    $char = "";
                    $ends_line_level = $new_line_level;
                    $new_line_level = NULL;
                    break;
            }
        } else if ( $char === '\\' ) {
            $in_escape = true;
        }
        if( $new_line_level !== NULL ) {
            $result .= "\n".str_repeat( "\t", $new_line_level );
        }
        $result .= $char.$post;
    }

    return $result;
}

Solution 3:

Many users suggested that you use

echo json_encode($results, JSON_PRETTY_PRINT);

Which is absolutely right. But it's not enough, the browser needs to understand the type of data, you can specify the header just before echo-ing the data back to the user.

header('Content-Type: application/json');

This will result in a well formatted output.

Or, if you like extensions you can use JSONView for Chrome.