jq语法错误提取名称中带有冒号的键 [英] jq syntax error extracting key with colon in its name

问题描述

我有以下JSON(可以从 https:中检索到): //openlibrary.org/api/books?bibkeys=ISBN:039397281X&format=json )作为输入:

I have the following JSON (which can be retrieved from https://openlibrary.org/api/books?bibkeys=ISBN:039397281X&format=json) as input:

{
  "ISBN:039397281X": {
    "bib_key": "ISBN:039397281X",
    "preview": "borrow",
    "thumbnail_url": "https://covers.openlibrary.org/b/id/7890978-S.jpg",
    "preview_url": "https://archive.org/details/isbn_9780393972818",
    "info_url": "https://openlibrary.org/books/OL348852M/Don_Quijote"
  }
}

我的目标是提取preview_url-因此，对于上面的输入，获得输出https://archive.org/details/isbn_9780393972818.

My goal is to extract the preview_url -- thus, for the input above, to get the output https://archive.org/details/isbn_9780393972818.

我当前正在使用以下内容:

I'm currently using the following:

curl 'https://openlibrary.org/api/books?bibkeys=ISBN:039397281X&format=json' \
  | jq -r '.ISBN:039397281X' | jq -r '.preview_url'

但是，这会发出一个错误:

However, this emits an error:

jq: error: syntax error, unexpected ':', expecting $end (Unix shell quoting issues?) at <top-level>, line 1:
.ISBN:039397281X     
jq: 1 compile error

如何解决?

推荐答案

您想要的是:

jq -r '.["ISBN:039397281X"].preview_url'

或更简单地说:

jq -r '.[].preview_url'

仅当foo是有效标识符时，语法.foo只能用于提取与键foo关联的值.冒号在标识符名称中无效，因此必须使用其他语法(.["foo"]).

The syntax .foo can only be used to extract the value associated with key foo when foo is a valid identifier. Colons are not valid in identifier names, so a different syntax (.["foo"]) must be used.

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