One of the most useful features in WordPress is the ability to add special fields to your posts. Some people use tools like Advanced Custom Fields or create their own custom fields for posts. You can use a powerful feature called “meta query” in WordPress to search for posts based on these custom fields.
In this article, we’ll learn how to find posts based on custom fields using the meta_query function in WordPress. This is particularly helpful for websites with lots of unique features. Just remember, you’ll need to know a bit about PHP to do this.
Query Posts By a Meta Value
One of the common ways to look for posts with a specific custom field is by focusing on a single value in that field.
Imagine you have a website where posts can be marked as “featured” using a special custom field. This is often done to highlight certain posts in a special section on the website.
<?php $meta_query_args = array( 'meta_query' => array( array( 'key' => 'featured_post', 'value' => 'yes', 'compare' => '=' ) ) ); $meta_query = new WP_Query( $meta_query_args );
The code provided will change based on the names you use for your fields and postmeta keys. In the ‘meta_query’ parameter, the ‘key’ refers to the custom field’s name, while the ‘value’ represents the specific value we’re searching for in posts. The ‘compare’ field is used to determine how we want to compare the values, which we’ll discuss later in this guide.
Using this approach with WP_Query helps us retrieve an array that can be used with loop functions to show posts. In this guide, we’re focusing on the ‘meta_query’ functions rather than explaining how to display the results of WP_Query.
Query Posts By Multiple Meta Values
If you need to compare a meta key value against several different values, it’s recommended to use the ‘IN’ operator. To do this, you can use an array for the ‘value’ field in your meta query.
Sure, here’s the code snippet in simpler words:
<?php
$meta_query_args = array(
'meta_query' => array(
array(
'key' => 'city_name',
'value' => array('New York City', 'London', 'San Francisco'),
'compare' => 'IN'
)
)
);
$meta_query = new WP_Query($meta_query_args);In this code, we’re creating a query to fetch posts based on a custom field called ‘city_name’. We’re looking for posts where the ‘city_name’ is either ‘New York City’, ‘London’, or ‘San Francisco’. The ‘compare’ parameter is set to ‘IN’ to indicate that we want to check if the value matches any of the provided values. Finally, the WP_Query object is used to execute the query.
Query Posts By Multiple Meta Keys
Sure, here’s a simpler explanation:
Now, let’s look at querying posts using multiple custom fields. This means we’re searching for posts that match specific conditions for more than one custom field. To achieve this, we’ll use an array to nest multiple queries and add a ‘relation’ parameter to the meta_query.
In other words, we’re combining the techniques we discussed earlier to search for posts that meet criteria from different custom fields. This way, we can find posts that match various conditions simultaneously.
<?php
$meta_query_args = array(
'meta_query' => array(
'relation' => 'AND',
array(
array(
'key' => 'city_name',
'value' => array('New York City', 'London', 'San Francisco'),
'compare' => 'IN'
),
array(
'key' => 'featured_post',
'value' => true,
'compare' => '='
)
)
)
);
$meta_query = new WP_Query( $meta_query_args );The ‘relation’ field can be set to ‘AND’ or ‘OR’. If you choose ‘AND’, all conditions must be true for a post to be selected. If you choose ‘OR’, only one condition needs to be true for a post to be chosen.
In this code, we’re using a more advanced method to query posts based on multiple custom fields. The ‘relation’ parameter helps us combine these queries using the ‘AND’ logic, meaning that both conditions must be met for a post to be returned.
We’re searching for posts that have the ‘city_name’ custom field with values like ‘New York City’, ‘London’, or ‘San Francisco’, and also the ‘featured_post’ field set to ‘true’. This allows us to find posts that match both of these criteria at the same time.
Query Posts Between Dates
Another common way to query WordPress posts using meta_query is to filter based on dates. Here’s how to retrieve only those posts that fall between two specific dates.
Keep in mind that this function expects dates to be formatted as YYYY-MM-DD. If you’re using Advanced Custom Fields, make sure your date format is set to this structure when returning the date.
<?php $meta_query_args = array( 'meta_query' => array( array( 'key' => 'my_date_field', 'value' => array( '2022-01-01', '2022-12-31' ), 'type' => 'date', 'compare' => 'BETWEEN' ) ) ); $meta_query = new WP_Query( $meta_query_args );
If you’re working with Unix timestamps, it’s even simpler to query posts between specific dates. This piece of code will change dates into Unix timestamps and then compare them to find posts within the given date range.
<?php
$meta_query_args = array(
'meta_query' => array(
array(
'key' => 'my_date_field',
'value' => array( strtotime('2022-01-01'), strtotime('2022-12-31') ),
'type' => 'numeric',
'compare' => 'BETWEEN'
)
)
);
$meta_query = new WP_Query( $meta_query_args );Certainly, you can also use the greater than or less than operator in the queries mentioned above to find posts that are either before or after a specific date.
Meta Query Comparison Operators
Here are some operators you can use to make specific queries for your posts using meta data. I’ll explain each operator and how you can use them.
- ‘=’ : Retrieves meta keys with values that match the specified value exactly.
- ‘!=’ : Retrieves meta keys with values that are not equal to the specified value.
- ‘>’ : Retrieves meta keys with values greater than the specified value.
- ‘>=’ : Retrieves meta keys with values greater than or equal to the specified value.
- ‘<‘ : Retrieves meta keys with values less than the specified value.
- ‘<=’ : Retrieves meta keys with values less than or equal to the specified value.
- ‘LIKE’ : Retrieves meta keys with values containing a specific word or phrase.
- ‘NOT LIKE’ : Retrieves meta keys with values that do not contain a specific word or phrase.
- ‘IN’ : Retrieves meta keys with values that are in a given array of values.
- ‘NOT IN’ : Retrieves meta keys with values that are not in a given array of values.
- ‘BETWEEN’ : Retrieves meta keys with values that fall between two specified values.
- ‘NOT BETWEEN’ : Retrieves meta keys with values that do not fall between two specified values.
- ‘EXISTS’ : Retrieves meta keys where a value exists.
- ‘NOT EXISTS’ : Retrieves meta keys where a value does not exist.
- ‘REGEXP’ : Retrieves meta keys based on a regular expression pattern.
- ‘NOT REGEXP’ : Retrieves meta keys that do not match a regular expression pattern.
Remember, if you’re not using an array in the meta_query, you’ll need to use meta_compare in your WP_Query arguments.
How To Sort Posts By Meta Fields
Certainly, with WordPress, you can arrange your posts by your custom fields using the ‘orderby’ option in WP_Query. This is simple to do by using the ‘orderby’ parameter in your WP_Query settings.
You should set ‘orderby’ as ‘meta_value’ and also choose a ‘meta_key’ which is the name of your custom field. Normally, this works best when you want your results in alphabetical order or sorted by numbers if your custom field has numbers.
And remember, you can also specify the ‘post_type’ parameter in your WP_Query to filter between ‘post’, ‘page’, or any other custom post type.
<?php $meta_query_args = array( 'post_type' => 'page', 'order' => 'ASC', 'meta_key' => 'city_name', 'orderby' => 'meta_value' ); $meta_query = new WP_Query( $meta_query_args );
If your meta_key field is a number, use the ‘meta_value_num’ value for orderby. This helps WordPress understand it’s an integer.
Great job! You’ve learned a valuable skill as a WordPress developer.
Using meta queries is really powerful when you’re creating custom features in WordPress. WordPress takes the parameters you provide in meta_query and translates them into SQL to search your database. If you’re building custom features, it’s better to use built-in WordPress functions instead of writing complex MySQL queries.
To expand your WordPress knowledge further, I recommend exploring the documentation for WP_Query.
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