Yaml and php files

yaml_parse

Convert all or part of a YAML document stream to a PHP variable.

Parameters

The string to parse as a YAML document stream.

Document to extract from stream ( -1 for all documents, 0 for first document, . ).

If ndocs is provided, then it is filled with the number of documents found in stream.

Content handlers for YAML nodes. Associative array of YAML tag => callable mappings. See parse callbacks for more details.

Return Values

Returns the value encoded in input in appropriate PHP type or false on failure. If pos is -1 an array will be returned with one entry for each document found in the stream.

Examples

Example #1 yaml_parse() example

$parsed = yaml_parse ( $yaml );
var_dump ( $parsed );
?>

The above example will output something similar to:

array(8) < ["invoice"]=>int(34843) ["date"]=> string(10) "2001-01-23" ["bill-to"]=> &array(3) < ["given"]=>string(5) "Chris" ["family"]=> string(6) "Dumars" ["address"]=> array(4) < ["lines"]=>string(34) "458 Walkman Dr. Suite #292" ["city"]=> string(9) "Royal Oak" ["state"]=> string(2) "MI" ["postal"]=> int(48046) > > ["ship-to"]=> &array(3) < ["given"]=>string(5) "Chris" ["family"]=> string(6) "Dumars" ["address"]=> array(4) < ["lines"]=>string(34) "458 Walkman Dr. Suite #292" ["city"]=> string(9) "Royal Oak" ["state"]=> string(2) "MI" ["postal"]=> int(48046) > > ["product"]=> array(2) < [0]=>array(4) < ["sku"]=>string(6) "BL394D" ["quantity"]=> int(4) ["description"]=> string(10) "Basketball" ["price"]=> int(450) > [1]=> array(4) < ["sku"]=>string(7) "BL4438H" ["quantity"]=> int(1) ["description"]=> string(10) "Super Hoop" ["price"]=> int(2392) > > ["tax"]=> float(251.42) ["total"]=> float(4443.52) ["comments"]=> string(68) "Late afternoon is best. Backup contact is Nancy Billsmer @ 338-4338." >

Notes

Processing untrusted user input with yaml_parse() is dangerous if the use of unserialize() is enabled for nodes using the !php/object tag. This behavior can be disabled by using the yaml.decode_php ini setting.

See Also

• yaml_parse_file() — Parse a YAML stream from a file
• yaml_parse_url() — Parse a Yaml stream from a URL
• yaml_emit() — Returns the YAML representation of a value

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yaml_parse_file

Convert all or part of a YAML document stream read from a file to a PHP variable.

Parameters

Document to extract from stream ( -1 for all documents, 0 for first document, . ).

If ndocs is provided, then it is filled with the number of documents found in stream.

Content handlers for YAML nodes. Associative array of YAML tag => callable mappings. See parse callbacks for more details.

Return Values

Returns the value encoded in input in appropriate PHP type or false on failure. If pos is -1 an array will be returned with one entry for each document found in the stream.

Notes

Processing untrusted user input with yaml_parse_file() is dangerous if the use of unserialize() is enabled for nodes using the !php/object tag. This behavior can be disabled by using the yaml.decode_php ini setting.

See Also

• yaml_parse() — Parse a YAML stream
• yaml_parse_url() — Parse a Yaml stream from a URL
• yaml_emit() — Returns the YAML representation of a value

User Contributed Notes 4 notes

Be aware that when parsing yaml an unquoted Y value will become a boolean true

This may be desired or undesired behavior depending on context

— chr_name: X // becomes string X
— chr_name: Y // becomes boolean true

You definitely don’t want chromosome Y becoming chromosome 1 (true) as happened to me, so heads up!

As Jesse Donat mentioned the type will be infered automatically. To enforce some type you can use the callback facility like this:

function cb_yaml_date ( $value , $tag , $flags ) return new DateTime ( $value );
>

$yaml = event1:
name: My Event
date: !date 25.05.2001
YAML;

$ndocs = 0 ;
$data = yaml_parse ( $yaml , 0 , $ndocs , array( ‘!date’ => ‘cb_yaml_date’ ));

print_r ( $data );
?>

The above example will output something similar to:

Array
(
[event1] => Array
(
[name] => My Event
[date] => DateTime Object
(
[date] => 2001-05-25 00:00:00
[timezone_type] => 3
[timezone] => Europe/Berlin
)

BTW if you want to have large numbers you are probably using BC Math. Thus, you simple enclose your number in quotes:

$yaml = largenumber: ‘14695760472279668267313200104308’
YAML;
?>

This is entirely dependent on type detection — as far as I can find there is no way to force a type and for instance when you have a very long integer as a value — in my case 1313035348823 it gets limited to 2147483647 — PHP’s max integer.

When trying to read an empty file, yaml_parse_file() throws a warning:

PHP Warning: yaml_parse_file(): end of stream reached without finding document 0

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Reading/Parsing and Writing YAML files, PHP Symfony

In this tutorial, we will explore how to use PHP for writing and parsing YAML files. Whether you are a PHP developer who wants to work with YAML files or just someone curious about this format, this post will offer you the necessary information to get started.

What is a YAML file?

A YAML (short for “YAML Ain’t Markup Language”) file is a human-readable text file format used for data serialization. Software applications frequently utilize this format to store configuration settings or exchange data between different systems.

Designers made YAML to be more human-readable than JSON and XML, despite its similarities to both formats. It uses a syntax that is based on indentation and uses colons and dashes to separate key-value pairs and lists.

This is a snippet of what you might expect to see in a YAML file:

This YAML file contains three key-value pairs, where the keys are “name”, “age”, and “email”, and the values are “Gav”, 37, and “[email protected]”.

The # character is used to indicate a comment, which is handily ignored by the parser.

Parsing and writing YAML files using Symfony Yaml component

Now that I have introduced you to YAML, let’s explore how to write and parse YAML files in PHP.

Installing Symfony Yaml using composer

If you want to follow along with this tutorial, it is a pre-requisite that you have Composer installed. To install the Symfony YAML component, open a terminal in the root of your project and enter the following command:

composer require symfony/yaml

Now that we have the Symfony reader installed we can include the namespace so that the YAML object is available to us. First we ‘require’ our composer ‘autoload.php’ file, and then we use the Symfony YAML namespace.

require "vendor/autoload.php"; use Symfony\Component\Yaml\Yaml;

The next part is simple; we can use the reader to parse the file.

Yaml::parseFile('path/to/yaml/file.yml');

The parseFile() method returns an associative array representing the parsed YAML data. We can then access the parsed data just like any other array.

$filePath = ''; $content = Yaml::parseFile($filePath); var_dump($content);

So how would this look when we actually parse a file? Let’s assume we parsed the previously exampled YAML file:

require "vendor/autoload.php"; use Symfony\Component\Yaml\Yaml; // Load the YAML file $content = Yaml::parseFile('/path/to/file.yaml'); // Access the parsed data echo $content['name']; echo $content['age']; echo $content['email'];

In these snippets we’re echoing out the name, age, and email by accessing the $content array. All you need to do is replace these keys with the appropriate keys from your own YAML file.

Writing YAML files in PHP

OK, so we can parse! Now we can explore how to write.

require "vendor/autoload.php"; use Symfony\Component\Yaml\Yaml; // Define the data to be written to the YAML file $input = [ 'user' => [ 'name' => 'Gav', 'website' => 'https://www.gavsblog.com' ] ]; // Convert the data to YAML format $yaml = Yaml::dump($data); // Write the YAML data to a file file_put_contents('/path/to/file.yaml', $yaml);

First we define the array of data that we want to write to a YAML file, then use the Yaml::dump() method to convert the data into YAML format.

Finally, we use file_put_contents() to write the YAML formatted data to a file located at /path/to/file.yaml.

Note: If the file does not exist, file_put_contents() will be create it for us. If the file already exists, the new YAML data will overwrite its contents unless we pass the FILE_APPEND boolean parameter as true (the third parameter).

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