javascript - 从 ajax 响应中提取 json 数据

Question

这是我的js函数

<script>        
function get_class_group(class_id) {

        $.ajax({
            url: '<?php echo base_url();?>index.php?admin/get_class_group/' + class_id ,
            success: function(response)
            {
                var obj = response;
                alert(obj);
            }
        });

    }

</script>

这给了我这样的输出

[{"section_id":"13","name":"A","nick_name":"A","class_id":"13","group_id":"4","teacher_id":"6","id":"4","group_name":"Science"}]
[{"section_id":"13","name":"A","nick_name":"A","class_id":"13","group_id":"4","teacher_id":"6","id":"4","group_name":"Science"},
{"section_id":"22","name":"B","nick_name":"b","class_id":"13","group_id":"4","teacher_id":"0","id":"4","group_name":"Science"}]

如果我写 alert(obj.section_id); 它给了我

error:"undefined".

如何从这个 json 中获取特定值？

这是我的后端函数:

function get_class_group($class_id) 
    {
        $this->db->select('section.*, class_group.*');
        $this->db->from('section');
        $this->db->join('class_group', 'section.group_id = class_group.id', 'left');
        $this->db->where('section.class_id', $class_id);
        $groups = $this->db->get()->result_array();

        foreach ($groups as $row) {
            $value[] = $row;
            echo json_encode($value);
        }

    }

Answer 1

使用一个each循环，你的响应是一个对象数组，使用stringify把字符串变成一个对象

$.ajax({
   url: '<?php echo base_url();?>index.php?admin/get_class_group/' + class_id ,
   success: function(response) {
     response = JSON.stringify(response);
     $.each(response,function(i,v){
       console.log(v.section_id);
     });
   }
});

将echo放在foreach函数之外

foreach ($groups as $row) {
            $value[] = $row;

        }
header('Content-Type: application/json');//add the json header if you want to remove the js stringify function 
echo json_encode($value);