What is the method for checking if a MyBatis list is empty?

2 years ago
William Carter
1 minute

In MyBatis, you can use the following method to determine if a List is empty:

  1. Check if a List is empty using OGNL expressions.
<if test="list != null and list.size() > 0">
    SELECT * FROM table WHERE id IN
    <foreach collection="list" item="item" open="(" separator="," close=")">
        #{item}
    </foreach>
</if>
  1. Use dynamic SQL tags for conditional checks.
<choose>
    <when test="list != null and list.size() > 0">
        SELECT * FROM table WHERE id IN
        <foreach collection="list" item="item" open="(" separator="," close=")">
            #{item}
        </foreach>
    </when>
    <otherwise>
        SELECT * FROM table
    </otherwise>
</choose>

In this way, SQL statements can be dynamically generated based on whether the List is empty. If the List is empty, the corresponding SQL statement will not be executed.

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