没有无限过滤链的JQ对象选择

Posted 2021-03-29

我在使用jq (1.5)来解析深层嵌套的JSON结构时遇到了困难，我觉得我使用它错了。以JSON输入为例：

{
 "a":[],
 "b":[
  {"x":"bar", "s":"FX", "f":["blorg","blarg","blurb"], "v":true},
  {"x":"bar", "s":"EX", "f":["blorg","blarg","bloob"], "v":false},
  {"x":"bar", "s":"XT", "f":["blorg","blart","bloop"], "v":true},
  {"x":"bar", "s":"IJ", "f":["blorg","bleep","glarp"], "v":true},
  {"x":"foo", "s":"IX", "f":["porg","parg","pork","peep"], "v":true},
  {"x":"baz", "s":"AB", "f":["zing","zang","zoop"], "v":false}
  ],
 "c":[]
}

• 要在列表b中提取x为“bar”的对象很简单： jq '.["b"][] | select(.x == "bar")' < file.json
• 要进一步限制具有特定值s的对象也很简单： jq '.["b"][] | select(.x == "bar" and .s == "FX")' < file.json

但是，如果我想应用正则表达式测试，或者需要字符串输入的任何其他测试（请记住我仍然需要对象输出），我想我别无选择，只能链接过滤器。例如 ...

• 要限制s以“X”结尾的对象，遗憾的是以下内容不是jq中的内容： jq '.["b"][] | select(.x == "bar" and .s.endswith("X"))' < file.json 相反，我认为我必须这样做： jq '.["b"][] | select(.x == "bar") | select(.s | endswith("X"))' < file.json
• 与s类似，包含“X”： jq '.["b"][] | select(.x == "bar") | select(.s | test("X"))' < file.json

如果我总是做布尔ANDs，这很好，但如果我想做一个OR怎么办？例如，什么是jq程序获取x为“bar”的对象OR s以“X”结尾？ jq有|OR|过滤器吗？

jq '.["b"][] | select(.x == "bar") |OR| select(.s | endswith("X"))' < file.json

或者我只是做错了？我是否试图重新发明一些标准的jq算法来选择对象？

答案

直截了当（在select函数中指定所有条件）：

jq -c '.b[] | select(.x == "bar" or (.s | endswith("X")))' file.json

输出：

{"x":"bar","s":"FX","f":["blorg","blarg","blurb"],"v":true}
{"x":"bar","s":"EX","f":["blorg","blarg","bloob"],"v":false}
{"x":"bar","s":"XT","f":["blorg","blart","bloop"],"v":true}
{"x":"bar","s":"IJ","f":["blorg","bleep","glarp"],"v":true}
{"x":"foo","s":"IX","f":["porg","parg","pork","peep"],"v":true}