通过另一个字段中的 1-indexed 值获取数组项

Question

Firefox 文件 sessionstore-backups/recovery.jsonlz4 以（压缩）JSON 格式包含有关当前 Firefox windows 的信息。这是代表该文件的简化格式：

{
  "index": 2,
  "entries": [
    {
      "title": "Foo bar 0",
      "url": "https://example.com/bar"
    },
    {
      "title": "Foo bar 1",
      "url": "https://example.com/bar"
    },
    {
      "title": "Foo bar 2",
      "url": "https://example.com/bar"
    }
  ]
}

index 字段表示每个选项卡当前显示的历史记录项。作为 1 索引，在上面的示例中它代表“Foo bar 1”条目。

如何使用 jq 中的值来获取该选项卡？

为了在您自己的系统上进行测试，下面的 bash 行将让您在大多数现代 Linux 系统上达到这一点：

lz4jsoncat ~/.mozilla/firefox/t6e99qbe.default-release/sessionstore-backups/recovery.jsonlz4 | jq '.windows[0].tabs' | jq 'sort_by(.lastAccessed)[-1]'

这 return 是最近的选项卡，但所有历史记录项都在 entries 数组中。由于用户可以在历史记录中返回，我们需要 index 值来确定 return 的条目。通过 gron 管道传输，它看起来像这样：

json = {};
json.attributes = {};
json.entries = [];
json.entries[0] = {};
json.entries[0].ID = 504;
json.entries[0].cacheKey = 0;
json.entries[0].docIdentifier = 586;
json.entries[0].docshellUUID = "{b6c1e18a-d0f5-4ba2-996e-ddd9fc28322a}";
json.entries[0].hasUserInteraction = true;
json.entries[0].persist = true;
json.entries[0].principalToInherit_base64 = "eyIxIjp7IjAiOiJtb3otZXh0ZW5zaW9uOi8vOTAzYWU2NDgtMzRlNi00NGQ3LTg0NjYtYzgxMWQyMTg2YjBkLyJ9fQ==";
json.entries[0].resultPrincipalURI = null;
json.entries[0].title = "Tridactyl Top Tips & New Tab Page";
json.entries[0].triggeringPrincipal_base64 = "eyIxIjp7IjAiOiJtb3otZXh0ZW5zaW9uOi8vOTAzYWU2NDgtMzRlNi00NGQ3LTg0NjYtYzgxMWQyMTg2YjBkLyJ9fQ==";
json.entries[0].url = "moz-extension://7ba85bcd-8d63-4e74-a723-e627a31d6274/static/newtab.html";
json.entries[1] = {};
json.entries[1].ID = 506;
json.entries[1].cacheKey = 0;
json.entries[1].docIdentifier = 588;
json.entries[1].docshellUUID = "{b6c1e18a-d0f5-4ba2-996e-ddd9fc28322a}";
json.entries[1].hasUserInteraction = true;
json.entries[1].persist = true;
json.entries[1].referrerInfo = "BBoSnxDOS9qmDeAnom1e0AAAAAAAAAAAwAAAAAAAAEYAAAAAAAEBAAAAAAEA";
json.entries[1].resultPrincipalURI = null;
json.entries[1].title = "Stack Overflow - Where Developers Learn, Share, & Build Careers";
json.entries[1].triggeringPrincipal_base64 = "eyIzIjp7fX0=";
json.entries[1].url = "https://whosebug.com/";
json.entries[2] = {};
json.entries[2].ID = 508;
json.entries[2].cacheKey = 0;
json.entries[2].csp = "CdntGuXUQAS/4CfOuSPZrAAAAAAAAAAAwAAAAAAAAEYB3pRy0IA0EdOTmQAQS6D9QJIHOlRteE8wkTq4cYEyCMYAAAAC/////wAAAbsBAAAAGmh0dHBzOi8vc3RhY2tvdmVyZmxvdy5jb20vAAAAAAAAAAUAAAAIAAAAEQAAAAj/////AAAACP////8AAAAIAAAAEQAAABkAAAABAAAAGQAAAAEAAAAZAAAAAQAAABoAAAAAAAAAGv////8AAAAA/////wAAABn/////AAAAGf////8BAAAAAAAAAAAAKHsiMSI6eyIwIjoiaHR0cHM6Ly9zdGFja292ZXJmbG93LmNvbS8ifX0AAAABAAAASwB1AHAAZwByAGEAZABlAC0AaQBuAHMAZQBjAHUAcgBlAC0AcgBlAHEAdQBlAHMAdABzADsAIABmAHIAYQBtAGUALQBhAG4AYwBlAHMAdABvAHIAcwAgACcAcwBlAGwAZgAnACAAaAB0AHQAcABzADoALwAvAHMAdABhAGMAawBlAHgAYwBoAGEAbgBnAGUALgBjAG8AbQAA";
json.entries[2].docIdentifier = 590;
json.entries[2].docshellUUID = "{b6c1e18a-d0f5-4ba2-996e-ddd9fc28322a}";
json.entries[2].hasUserInteraction = true;
json.entries[2].persist = true;
json.entries[2].principalToInherit_base64 = "eyIxIjp7IjAiOiJodHRwczovL3N0YWNrb3ZlcmZsb3cuY29tLyJ9fQ==";
json.entries[2].referrerInfo = "BBoSnxDOS9qmDeAnom1e0AAAAAAAAAAAwAAAAAAAAEYBAAAAGmh0dHBzOi8vc3RhY2tvdmVyZmxvdy5jb20vAAAACAEBAAAAGmh0dHBzOi8vc3RhY2tvdmVyZmxvdy5jb20vAQE=";
json.entries[2].resultPrincipalURI = null;
json.entries[2].title = "Highest scored questions - Stack Overflow";
json.entries[2].triggeringPrincipal_base64 = "eyIxIjp7IjAiOiJodHRwczovL3N0YWNrb3ZlcmZsb3cuY29tLyJ9fQ==";
json.entries[2].url = "https://whosebug.com/questions";
json.entries[3] = {};
json.entries[3].ID = 510;
json.entries[3].cacheKey = 0;
json.entries[3].csp = "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";
json.entries[3].docIdentifier = 592;
json.entries[3].docshellUUID = "{b6c1e18a-d0f5-4ba2-996e-ddd9fc28322a}";
json.entries[3].hasUserInteraction = true;
json.entries[3].persist = true;
json.entries[3].principalToInherit_base64 = "eyIxIjp7IjAiOiJodHRwczovL3N0YWNrb3ZlcmZsb3cuY29tL3F1ZXN0aW9ucyJ9fQ==";
json.entries[3].referrerInfo = "BBoSnxDOS9qmDeAnom1e0AAAAAAAAAAAwAAAAAAAAEYBAAAAI2h0dHBzOi8vc3RhY2tvdmVyZmxvdy5jb20vcXVlc3Rpb25zAAAACAEBAAAAI2h0dHBzOi8vc3RhY2tvdmVyZmxvdy5jb20vcXVlc3Rpb25zAQE=";
json.entries[3].resultPrincipalURI = null;
json.entries[3].title = "Tags - Stack Overflow";
json.entries[3].triggeringPrincipal_base64 = "eyIxIjp7IjAiOiJodHRwczovL3N0YWNrb3ZlcmZsb3cuY29tL3F1ZXN0aW9ucyJ9fQ==";
json.entries[3].url = "https://whosebug.com/tags";
json.entries[4] = {};
json.entries[4].ID = 512;
json.entries[4].cacheKey = 0;
json.entries[4].csp = "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";
json.entries[4].docIdentifier = 594;
json.entries[4].docshellUUID = "{b6c1e18a-d0f5-4ba2-996e-ddd9fc28322a}";
json.entries[4].hasUserInteraction = false;
json.entries[4].persist = true;
json.entries[4].principalToInherit_base64 = "eyIxIjp7IjAiOiJodHRwczovL3N0YWNrb3ZlcmZsb3cuY29tL3RhZ3MifX0=";
json.entries[4].referrerInfo = "BBoSnxDOS9qmDeAnom1e0AAAAAAAAAAAwAAAAAAAAEYBAAAAHmh0dHBzOi8vc3RhY2tvdmVyZmxvdy5jb20vdGFncwAAAAgBAQAAAB5odHRwczovL3N0YWNrb3ZlcmZsb3cuY29tL3RhZ3MBAQ==";
json.entries[4].resultPrincipalURI = null;
json.entries[4].title = "Users - Stack Overflow";
json.entries[4].triggeringPrincipal_base64 = "eyIxIjp7IjAiOiJodHRwczovL3N0YWNrb3ZlcmZsb3cuY29tL3RhZ3MifX0=";
json.entries[4].url = "https://whosebug.com/users";
json.hidden = false;
json.index = 3;
json.lastAccessed = 1651407567904;
json.requestedIndex = 0;
json.searchMode = null;
json.userContextId = 0

Answer 1

只是索引 entries index 减一？

.entries[.index - 1]

^{Online demo}

通过另一个字段中的 1-indexed 值获取数组项

Get array item by 1-indexed value in another field

json

jq