php - 使用php和mysql以json格式进行分类多级显示

Question

我需要以json格式显示类别及其子类别，这里的问题是每个类别都有无限的级别，有些类别有4个级别，有些有2个和有些3个级别。我尝试了一种解决方案，它只显示一个级别下的一个，但我需要显示所有级别。

表架构:

代码示例:

function categories() {
        header('Content-Type: application/json');
        $sql = "select id,name,parent_id from categories where parent_id = 0";
        $q = $this->db->conn_id->prepare($sql);
        $q->execute();
        $main_cat = array();
        while ($row = $q->fetch(PDO::FETCH_ASSOC)) {
            $sql2 = "select id,name,parent_id from categories where parent_id = ?";
            $sub_cat = array();
            $r = $this->db->conn_id->prepare($sql2);
            $r->bindParam(1, $row['id']);
            $r->execute();
            while ($row1 = $r->fetch(PDO::FETCH_ASSOC)) {
                array_push($sub_cat, array_filter($row1));
            }
            $row['subcategories'] = $sub_cat;
            array_push($main_cat, array_filter($row));
        }
        echo json_encode(array("categories" => $main_cat));
    }

以上代码 Json 响应示例:

{"categories":[{"id":"1","name":"Development","subcategories":[{"id":"2","name":"All Development","parent_id":"1"},{"id":"3","name":"Web Development","parent_id":"1"},{"id":"12","name":"Mobile Apps","parent_id":"1"}]},{"id":"4","name":"Design","subcategories":[{"id":"5","name":"All Design","parent_id":"4"}]},{"id":"11","name":"IT & Software"}]}

任何人都可以帮助我解决这个问题。

Answer 1

我已经尝试过这个解决方案对我有用。

function categories() {
        $sql = "SELECT * FROM categories where parent_id = 0";
        $results = $this->db->conn_id->prepare($sql);
        $results->execute();
        while ($result = $results->fetch(PDO::FETCH_ASSOC)) {
            $subcat = array();
            $id = $result['id'];
            $childs = $this->hasChilds($id);
            $categories[] = array("id" => $result['id'], "name" => $result['name'], "parent_id" => $result['parent_id'], "subcats" => array_filter($childs));
        }
        echo json_encode($categories);
    }

    function hasChilds($id) {
        $sql = "SELECT * FROM categories where parent_id = ? ";
        $results = $this->db->conn_id->prepare($sql);
        $results->bindParam(1, $id);
        $results->execute();
        $count = $results->rowCount();
        $array = array();
        if ($count > 0) {
            while ($result = $results->fetch(PDO::FETCH_ASSOC)) {
                $array[] = array("id" => $result['id'], "name" => $result['name'], "parent_id" => $result['parent_id'], "subcats" => array_filter($this->hasChilds($result['id'])));
            }
        } else {
            $array[] = null;
        }
        return $array;
    }