wp query详解

如果你query要设置一篇为特色文章放大，其他几篇放小的话，如何设置才能不重复单独放大一篇呢，要用到wp query的属性之一，post__not_in. 你可以在第一个个query里面设置下读取他的id，然后在第二个query里设置下post__not_in 这个id的post. 基本的query格式为，

<section class="container">

	<article class="main">

		<?php

		$query = new WP_Query(array(
			'posts_per_page'  => 1,
			'post_type'  => 'post'

		));

		while($query->have_posts()) : $query->the_post(); $nowshowid = $post->ID;


		 ?>

		 <div class="featured">
		 	<h1><?php the_title(); ?></h1>
		 </div>


		<?php endwhile; wp_reset_postdata(); ?>


		<ul>
			<?php 

			$query2 = new WP_Query(array(
				'post_type'  => 'post',
				'posts_per_page'  => 20,
				'orderby' => 'comment_count',
				'order' => 'DESC',
				'post__not_in'  => [$nowshowid]

			));


			while ($query2->have_posts()) {
		    $query2->the_post(); ?>

   		    	<li>
		    		<a href="<?php the_permalink() ?>"><?php the_title(); ?></a>
		    		<?php the_excerpt(); ?>
		    	</li>
		 

		    <?php 
		} wp_reset_postdata(); ?>
		</ul>
		
	</article>

</section>

如果要按找自定义字段进行排序，怎么办？这里比方说我们每个帖子里有个排序的自定义字段，内容都是数字。怎样设置下才能按照这个数字进行排序？这里就要用到自定义排序的方式，很重要的一个方式就是按找meta_value 排序，也就是’orderby’ => ‘meta_value’, 之前要申明meta_key的数值，也就是自定义字段order.

所有$post变量带的数据都形成了post的元数据，也就是meta_value, 而meta_key就是元数据的查询方法。如果以自定义字段order作为排序的写法就是：

$query2 = new WP_Query(array(
				'post_type'  => 'post',
				'posts_per_page'  => 20,
				'meta_key'  => 'order',
				'orderby' => 'meta_value',
				'order' => 'ASC',
				'post__not_in'  => [$nowshowid]

			));


			while ($query2->have_posts()) {
		    $query2->the_post(); ?>

   		    	<li>
		    		<a href="<?php the_permalink() ?>"><?php the_title(); ?></a>
		    		<?php the_excerpt(); ?>
		    	</li>
		 

		    <?php 
		} wp_reset_postdata(); ?>

注意，如果用做数字的排序的话，排序的orderby可以写成meta_value_num。专门数字排序的方法。

如果要进行data比较排序的话，要用到高级的排序方法。

wp query有两种高级的排序方法，一种是meta_query,用到的是自定义字段的高级排序，一种是tax_query，排序的是分类形式。

meta_query是查询和比较多个字段。只有一个字段的query的方式如下：

<?php 

			$query2 = new WP_Query(array(
				'post_type'  => 'post',
				'posts_per_page'  => 20,
				'orderby'  => 'meta_value',
				'meta_key'  => 'order',
				'meta_compare' => '<=',
				'meta_value'  => 5,


				//'order' => 'ASC',
				//'post__not_in'  => [$nowshowid]

			));


			while ($query2->have_posts()) {
		    $query2->the_post(); ?>

   		    	<li>
		    		<a href="<?php the_permalink() ?>"><?php the_title(); ?></a>
		    		<?php the_excerpt(); ?>
		    	</li>
		 

		    <?php 

这个query就查询了字段名称为order,数值小于等于5的所有帖子。注意每个项目的用法。

meta_query写法：

$query2 = new WP_Query(array(
				'post_type'  => 'post',
				'posts_per_page'  => 20,
				'meta_query'  => array(
					'relation'  => 'OR',  //默认是AND
					array(
						'key'  => 'order',
						'value'  => '80',
						'type'  => 'CHAR',
						'compare'  => '<='

						),
					array(
							'key'  => 'price',
							'value'  => 100,
							'type'  => 'NUMERIC',
							'compare'  => '<'

					)
				),
				'post__not_in'  => [$nowshowid]

			));


			while ($query2->have_posts()) {
		    $query2->the_post(); ?>

   		    	<li>
		    		<a href="<?php the_permalink() ?>"><?php the_title(); ?></a>
		    		<?php the_excerpt(); ?>
		    	</li>
		 

		    <?php 
		} wp_reset_postdata();

如果要查询自定义字段区间在1-6之间的文章，可以用到compare的between方法，如下：

'meta_query'  => array(
					
					array(
							'key'  => 'order',
							'value'  => array(1,3),
							'type'  => 'NUMERIC',
							'compare'  => 'BETWEEN'

					)
				),

meta query可以内嵌的，比方说你要先查询一个逻辑，颜色是绿色，尺寸是大号的，这个结果当作A， 你要同时查询一个结果， 编号是＜5的，结果是B，你要A结果和B结果一起查询，所以A结果你要先写一个array,写上relation, 然后再写两个array， 进行查询。

category参数、tags参数的用法：

// Category Parameters - Show posts associated with certain categories.
// http://codex.wordpress.org/Class_Reference/WP_Query#Category_Parameters
  'cat' => 5, // (int) - Display posts that have this category (and any children of that category), using category id.
  'cat' => '-12,-34,-56' // Display all posts except those from a category by prefixing its id with a '-' (minus) sign.
  'category_name' => 'staff, news', // (string) - Display posts that have these categories (and any children of that category), using category slug.
  'category_name' => 'staff+news', // (string) - Display posts that have "all" of these categories, using category slug.
  'category__and' => array( 2, 6 ), // (array) - Display posts that are in multiple categories. This shows posts that are in both categories 2 and 6.
  'category__in' => array( 2, 6 ), // (array) - Display posts that have this category (not children of that category), using category id.
  'category__not_in' => array( 2, 6 ), // (array) - Display posts that DO NOT HAVE these categories (not children of that category), using category id.

// Tag Parameters - Show posts associated with certain tags.
// http://codex.wordpress.org/Class_Reference/WP_Query#Tag_Parameters
  'tag' => 'cooking', // (string) - use tag slug.
  'tag_id' => 5, // (int) - use tag id.
  'tag__and' => array( 2, 6), // (array) - use tag ids.
  'tag__in' => array( 2, 6), // (array) - use tag ids.
  'tag__not_in' => array( 2, 6), // (array) - use tag ids.
  'tag_slug__and' => array( 'red', 'blue'), // (array) - use tag slugs.
  'tag_slug__in' => array( 'red', 'blue'), // (array) - use tag slugs.

tax_query的用法：

// Taxonomy Parameters - Show posts associated with certain taxonomy.
// http://codex.wordpress.org/Class_Reference/WP_Query#Taxonomy_Parameters
// Important Note: tax_query takes an array of tax query arguments arrays (it takes an array of arrays)
// This construct allows you to query multiple taxonomies by using the relation parameter in the first (outer) array to describe the boolean relationship between the taxonomy queries.
  'tax_query' => array( // (array) - use taxonomy parameters (available with Version 3.1).
    'relation' => 'AND', // (string) - The logical relationship between each inner taxonomy array when there is more than one. Possible values are 'AND', 'OR'. Do not use with a single inner taxonomy array. Default value is 'AND'.
    array(
      'taxonomy' => 'color', // (string) - Taxonomy.
      'field' => 'slug', // (string) - Select taxonomy term by Possible values are 'term_id', 'name', 'slug' or 'term_taxonomy_id'. Default value is 'term_id'.
      'terms' => array( 'red', 'blue' ), // (int/string/array) - Taxonomy term(s).
      'include_children' => true, // (bool) - Whether or not to include children for hierarchical taxonomies. Defaults to true.
      'operator' => 'IN' // (string) - Operator to test. Possible values are 'IN', 'NOT IN', 'AND', 'EXISTS' and 'NOT EXISTS'. Default value is 'IN'.
    ),
    array(
      'taxonomy' => 'actor',
      'field' => 'id',
      'terms' => array( 103, 115, 206 ),
      'include_children' => false,
      'operator' => 'NOT IN'
    )
  ),

自定义筛选的样例：

<?php 

	if ($_GET['minprice'] && !empty($_GET['minprice'])) {
		$minprice = $_GET['minprice'];
	} else {
		$minprice = 0;
	}

	if ($_GET['maxprice'] && !empty($_GET['maxprice'])) {
		$maxprice = $_GET['maxprice'];
	}  else {
		$maxprice = 99999;
	}

	if ($_GET['size'] && !empty($_GET['size'])) {
		$size = $_GET['size'];
	} 

	if ($_GET['color'] && !empty($_GET['color'])) {
		$color = $_GET['color'];
	} 

	echo $minprice . $maxprice . $size . $color;

	?>


	<div class="filter">
		<h1>Category filter</h1>
		<div class="container">
			<form action="<?php echo site_url('/') ?>" method="get">
				<label>min:</label>
				<input type="number" name="minprice" <?php echo $minprice; ?>>
				<label>max:</label>
				<input type="number" name="maxprice" <?php echo $maxprice; ?>>

				<label>Size:</label>
				<select name="size" id="">
					<option value="">ANY</option>
					<option value="s">S</option>
					<option value="m">M</option>
					<option value="l">L</option>
					<option value="xl">XL</option>
				</select>

				<label>Color:</label>
				<select name="color" id="">
					<option value="">ANY</option>
					<option value="red">RED</option>
					<option value="blue">BLUE</option>
					<option value="pink">PINKL</option>
					<option value="beige">BEIGE</option>
				</select>

				<button type="submit" name="">FILTER</button>
			</form>
		</div>
	</div>

	<div class="category">
		<strong>Tags:</strong>
		<?php 

		$catpost = new WP_Query(array(
			'post_type'  => 'post',
			'posts_per_page'  => -1,
			'meta_query'  => array(
				'relation'  => 'AND',

				array(
					'key'  => 'price',
					'type'  => 'NUMERIC',
					'value'  => array($minprice,$maxprice),
					'compare'  => 'BETWEEN'

				),
				array(
					'key'  => 'size',
					
					'value'  => $size,
					'compare'  => 'LIKE'  //用like原因是当size没有属性的时候就会通配所有，因为我们设置了$size必须设置不空的时候有值。 作为通配符而存在。 比方说设置value作为 bl的话，compare设置为LIKE, 就会统配bl*类型 也就是数据库存在的blue. 

				)),

				array(
						'key'  => 'color',
						
						'value'  => $color,
						'compare'  => 'LIKE'  //用like原因是当size没有属性的时候就会通配所有，因为我们设置了$size必须设置不空的时候有值。 作为通配符而存在。 比方说设置value作为 bl的话，compare设置为LIKE, 就会统配bl*类型 也就是数据库存在的blue. 

					)),
				);

				
		

		while($catpost->have_posts()) : $catpost->the_post();

		 ?>


		 <h3><?php the_category(); ?></h3>
		 <a href="<?php the_permalink() ?>"><?php the_title(); ?></a>
		 <?php the_tags( ); ?>
		 <h2 style="color: red">Price:<?php the_field('price') ?></h2>

		<?php endwhile; ?>
		
	</div>

select设置选中结果的话要设置options selected属性为selectd.

<option selected="selected">
3
</option>