Custom Field Search in Wordpress - php

Question

I am looking for a way to filter my posts by custom fields,
for example this link:
mywebsite.com/?color:red
looks for all the post that has custom field named color and the value red
I will be appreciate it if you can help me, I searched all over internet and I got nothing.

Answer 1

I don't know if it's a typo but the example link you provided will not work. Query format is like this, ?property=value&another_property=another_value.
If your query is mywebsite.com/?color=red you can use the $_GET to get the value from the query and use it for what ever you need.
// check if we have a query property of color and that property has a value
if (isset($_GET['color']) && !empty($_GET['color'])) {
// filter the result and remove any spaces
$color = trim(filter_input(INPUT_GET, 'color', FILTER_SANITIZE_STRING));
// Create the arguments for the get_posts function
$args = [
'posts_per_page' => -1, // or how many you need
'post_type' => 'YOUR_POST_TYPE', // if the post type is 'post' you don't need this line
'post_status' => 'publish', // get only the published posts
'meta_query' => [ // Here we use our $_GET data to find all posts that have the value of red in a meta field named color
[
'key' => 'color',
'value' => $color,
'compare' => '='
]
]
];
$posts = get_posts($args);
}
if (!empty($posts)) {
// Now you can loop $posts and do what ever you want
}
Hope this helps =].
EDIT
Answering your question about getting posts with multiple meta values.
if ((isset($_GET['color']) && !empty($_GET['color'])) && (isset($_GET['size']) && !empty($_GET['size']))) {
// filter the result and remove any spaces
$color = trim(filter_input(INPUT_GET, 'color', FILTER_SANITIZE_STRING));
$size = trim(filter_input(INPUT_GET, 'size', FILTER_SANITIZE_STRING));
// Create the arguments for the get_posts function
$args = [
'posts_per_page' => -1, // or how many you need
'post_type' => 'YOUR_POST_TYPE', // if the post type is 'post' you don't need this line
'post_status' => 'publish', // get only the published posts
'meta_query' => [ // now we are using multiple meta querys, you can use as many as you want
'relation' => 'OR', // Optional, defaults to "AND" (taken from the wordpress codex)
[
'key' => 'color',
'value' => $color,
'compare' => '='
],
[
'key' => 'size',
'value' => $size,
'compare' => '='
]
]
];
$posts = get_posts($args);
}
if (!empty($posts)) {
// Now you can loop $posts and do what ever you want
}

Answer 2

You can use the ACF-fields in a Meta Query like this:
$posts = get_posts(array(
'numberposts' => -1,
'post_type' => 'post',
'meta_key' => 'color',
'meta_value' => 'red'
));
There are more examples in the ACF documentation:
https://www.advancedcustomfields.com/resources/query-posts-custom-fields/#custom-field%20parameters