求高手指点关于PHP json_decode函数使用

Question

小弟在做一个小项目时将一些数组json_encode以后，存入mysql库中，从MYSQL中读出后想用json_decode转换却返回null。库中存入的值是这样的格式的  [{"id":"14","dishname":"红烧鲫鱼","price":"68","num":1},{"id":"16","dishname":"泉水豆花","price":"28","num":2},{"id":"17","dishname":"稻草扎肉","price":"20","num":1},{"id":"21","dishname":"六月黄","price":"118","num":1}]后来查资料得知mysql中读出的文本要转换成对象才能json_decode  不知道哪位高人能帮忙解决一下，万分感激。

Answer 1

转换后的对象可以直接如下访问$data = json_decode($str);
echo $data[0]->id;

Answer 2

回楼上的，从MYSQL中读出的数据
[{"id":"14","dishname":"红烧鲫鱼","price":"68","num":1},{"id":"16","dishname":"泉水豆花","price":"28","num":2},{"id":"17","dishname":"稻草扎肉","price":"20","num":1},{"id":"21","dishname":"六月黄","price":"118","num":1}]
是文本，不能用json_decode转换的，返回值是null，求如何解决啊。