使用jq合并具有公共ID的密钥 [英] Use jq to merge keys with common id

问题描述

考虑文件"b.json":

consider a file 'b.json':

[
  {
    "id": 3,
    "foo": "cannot be replaced, id isn't in a.json, stay untouched",
    "baz": "do not touch3"
  },
  {
    "id": 2,
    "foo": "should be replaced with 'foo new2'",
    "baz": "do not touch2"
  }
]

和'a.json':

[
  {
    "id": 2,
    "foo": "foo new2",
    "baz": "don't care"
  }
]

我想使用jq和来自a.json的匹配值来更新b.json中的键"foo".它也应该与a.json中的多个条目一起使用.

I want to update the key "foo" in b.json using jq with the matching value from a.json. It should also work with more than one entry in a.json.

因此所需的输出是:

[
  {
    "id": 3,
    "foo": "cannot be replaced, id isn't in a.json, stay untouched",
    "baz": "do not touch3"
  },
  {
    "id": 2,
    "foo": "foo new2",
    "baz": "do not touch2"
  }
]

推荐答案

以下是使用INDEX/2的几种可能性之一.如果您的jq没有内置此功能，请参见下文.

Here's one of several possibilities that use INDEX/2. If your jq does not have this as a built-in, see below.

jq --argfile a a.json '
  INDEX($a[]; .id) as $dict
  | map( (.id|tostring) as $id
         | if ($dict|has($id)) then .foo = $dict[$id].foo 
           else . end)' b.json

还有其他方法可以传递a.json和b.json的内容.

There are other ways to pass in the contents of a.json and b.json.

上面对INDEX的使用假定不存在冲突"，例如，如果其中一个对象的.id等于1，而另一个对象的.id等于"1"，则将发生冲突".如果有可能发生这种冲突，则可以使用更复杂的INDEX定义.

The above use of INDEX assumes there are no "collisions", which would happen if, for example, one of the objects has .id equal to 1 and another has .id equal to "1". If there is a possibility of such a collision, then a more complex definition of INDEX could be used.

直接从Builtin.jq:

Straight from builtin.jq:

def INDEX(stream; idx_expr):
  reduce stream as $row ({}; .[$row|idx_expr|tostring] = $row);

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