mongodb如何实现mysql里的replace用法

Question

例如：mysql里：
UPDATE tb1 SET f1=REPLACE(f1, 'abc', 'def');
那么在mongodb下，如何实现类似的用法？就是针对collection中某个key的值value，进行字符串替换。

Answer 1

Customized func, very convenient

Visually guess that you want to operate in batches, mapreduce