JSON and PHP: formatting and validating
Formatting JSON to look all lovely
It's always a happy day when I manage to use JSON in PHP. As a JS developer, it sort of feels like I'm marrying the two technologies. Take that, serialised arrays - I'm using JSON.
PHP, of course, has support for encoding and decoding JSON via json_encode() and json_decode() respectively. What it can't do natively, though, is format JSON.
Why would you want to format JSON in PHP to make it look all nice and indented? Well, if the system you're building uses JSON for a config file, and you want users to be able to edit that config file within the system, in a textarea, say.
I then found this function, which largely does the job.
It can, however, get the indentation wrong sometimes. Also, it can leave whitespace at the end of lines. So I extended it slightly. The following three snippets should be inserted just before the final return statement.
Firstly, let's clear any whitespace left at the end of lines.
$result = preg_replace('/\t+\n/', "\n", $result);
Next, let's fix the indentation. What I noticed was that the script was indenting lines containing closing brackets/braces precisely double what it should be - so four tabs instead of two, for example. So, the following halves each case.
1function PR_callback($match) { return substr($match[1], 0, strlen($match[1]) / 2).$match[2]; }
2$result = preg_replace_callback('/^(\t+)(\]|\})/m', 'PR_callback', $result);
Note I'm using a callback on preg_replace() - this gives me greater control over the nature of my replacements. preg_replace() automatically forwards to my callback one argument - an array of the match. As ever, key 0 in the array contains the whole match and any subsequent keys contain any sub-matches my pattern looked for.
Lastly, either the script or (more probably) my hacks above end up killing some of the line breaks, so let's restore them.
$result = preg_replace('/([^\t]+)\t/', "$1\n\t", $result);
Et voila - nicely formatted JSON.
Make sure your JSON's valid
JSON and JavaScript Object Notation are not always the same thing. How so? Well, this is valid JS but INvalid JSON:
1var someObj = {
2 one: 'one',
3 two: 'two'
4}
...because the JSON spec demands that a) property names are quoted; b) property names and strings must be encased in double, not single quotes.
So if you end up with invalid JSON, how will you know? PHP >= 5.3 defines json_last_error(), which returns a flag saying what went wrong.
Confusingly, it returns something even if nothing went wrong - JSON_ERROR_NONE. It does not return false, so it is insufficient to check the validity of JSON with:
1$badJSON = '{one: "one"}';
2$array = json_decode($badJSON, true); //2nd param means we get back an assoc. array, not an object
3if (!json_last_error()) echo "All OK!";
Instead, the last line should be:
if (json_last_error() != JSON_ERROR_NONE) echo "All OK!";
PHP versions prior to 5.3
If you're running PHP prior to v.5.3, you won't have json_last_error(). Instead, you can simply check the truthy/falsy value of json_decode(), so:
1$array = json_decode($badJSON, true);
2if (!$array) echo "Problem!";
Obviously this approach is more crude and won't tell you what went wrong - just that something did.
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post a commentXML-to-JSON remapper - now RSS friendly
I've had a great response to my XML-to-JSON convertor and remapper. Its ability to not only convert but also remap data on the fly, to your precise structural requirements, has gone down particularly well.
One flaw raised today, though, was that it didn't work with RSS fees. Standard XML feeds, yes, but not RSS. After some digging I realised why.
The plugin expected the iteration node (i.e. the repeated node whose data will form the sub-objects of your JSON data) to directly follow the root node, e.g.
1<root>
2 <news_story>
3 <headline>foo</headline>
4 <url>bar.html</url>
5 </news_story>
6</root>
But if your XML had more levels - such as the following, typical of RSS:
1<rss>
2 <channel>
3 <news_story>
4 <headline>foo</headline>
5 <url>bar.html</url>
6 </news_story>
7 </channel>
8</rss>
...it didn't play ball. This has been countered by the addition of a new second argument when calling the plugin, in which you pass a space-separated selector string matching the iteration node, so for the above two examples this would be 'root news_story' and 'rss channel news_story', respectively.
Happy days! Head over here to download, get usage info or view a demo.
I've also been asked about whether the plugin supports XML node attributes. No, but it will. Stay posted...
post a commentXML-to-JSON convertor and remapper
After much hair-pulling and cursing, my XML-to-JSON convertor and remapper is finally here.
The real power behind this plugin is its ability to not only convert but also REMAP your data on the fly. There are other plugins out there that handle conversion, but I've not seen any that also remap.
This has the potential to be hugely useful.
Imagine you're using a news ticker that requires JSON data (for the headlines, URLs etc), but you want to populate it with data from an XML feed you don't have control over, and whose property names and hierarchical structure is different from what your ticker needs:
1<item>
2 <one>foo</one>
3 <two>bar</two>
4 <three>
5 <four>foobar</four>
6 </three>
7</item>
but you need
1{
2 one: 'foo',
3 two: 'bar',
4 three: 'foobar'
5}
...so not only a conversion but also a structural change. You can achieve that with this plugin.
Head over here to download, get usage info or view a demo.
post a comment
