Trying to add an array to an associated array-CodePudding

I have an associated array saved in my database that Im saving to a variable called response_cost using the Wordpress function get_post_meta.

$response_cost = get_post_meta( $postID, $metaKey, true );

The array looks something like this:

a:2: {
    i:0;a:3:
        {s:4:"type";s:6:"months";s:4:"cost";s:0:"";s:8:"modifier";s:1:"=";}
    i:1;a:3:
        {s:4:"type";s:5:"weeks";s:4:"cost";s:0:"";s:8:"modifier";s:1:" ";}
}

I have a form that I've created which outputs a new array and it's saved in a variable called $add_to_response_cost.

$add_to_response_cost = array (
    'type' => $type,
    'cost' => $cost,
    'modifyer' => $modifyer
);

I'm can't figure out how to add $add_to_response_cost as another instance of $response_cost so that the out put ends up like so:

a:3: {
    i:0;a:3:
        {s:4:"type";s:6:"months";s:4:"cost";s:0:"";s:8:"modifier";s:1:"=";}
    i:1;a:3:
        {s:4:"type";s:5:"weeks";s:4:"cost";s:0:"";s:8:"modifier";s:1:" ";}
    i:2;a:3:
        { my new array I've constructed via $add_to_response_cost }
}

Any help or direction with this is greatly appreciated.

CodePudding user response：

You can try unserialize() to convert it to array.

$result = unserialize($response_cost);

Print_r($result);

CodePudding user response：

To understand the problem, first we need to explain a little about how saving arrays in custom fields works

Here we have an array

$array = array(
     "0" => array(
       "type" => "months",
       "cost" => null,
       "modifier" => "=",
     ),
     "1" => array(
      "type" => "weeks",
      "cost" => null,
      "modifier" => " ",
)
);

If we decide to save it as a custom field in the database, we use the update_post_meta() function

update_post_meta( 1, 'response_cost', $array );

Before saving it to the database, Wordpress will serialize our array and then put it into the database.

As a result, the array will be saved in the database in the following format

a:2:{i:0;a:3:{s:4:"type";s:6:"months";s:4:"cost";N;s:8:"modifier";s:1:"=";}i:1;a:3:{s:4:"type";s:5:"weeks";s:4:"cost";N;s:8:"modifier";s:1:" ";}}

Then, if we want to get an array, we use get_post_meta()

$myarray = get_post_meta(1, "response_cost", true);

Wordpress will take a serialized array from the database and convert it to a typical array.

Then we can add any data we want to the array and save it back to the database.

$add_to_response_cost = array (
    'type' => $type,
    'cost' => $cost,
    'modifyer' => $modifyer
);

$myarray[] = $add_to_response_cost;

update_post_meta( 1, 'response_cost', $myarray );

Usually this problem occurs when using the get_post_meta function without specifying a key, with only one parameter (ID), then we get arrays without processing and they must first be unserialized

This can also happen when you get an array from a database not through a Wordpress function, but by direct SQL query to the database. Then you need to unserialize the array first, add data to it and pack it back.