jq - 在一行中列印值

json輸入：

[
 {
   "name": "cust1",
   "grp": [
     {
       "id": "46",
       "name": "BA2"
     },
     {
       "id": "36",
       "name": "GA1"
     },
     {
       "id": "47",
       "name": "NA1"
     },
     {
       "id": "37",
       "name": "TR3"
     },
     {
       "id": "38",
       "name": "TS1"
     }
   ]
 }
]

預期，輸出是兩行：

name: cust1
groups: BA2 GA1 NA1 TR3 TS1

我試圖建構過濾器但沒有成功..

$ jq -r '.[]|"name:", .name, "groups:", (.grp[]|[.name]|@tsv)' test_json
name:
cust1
groups:
BA2
GA1
NA1
TR3
TS1

更新：下面提供的解決方案工作正常，但我沒有預測不存在組的情況：

[
 {
   "name": "cust1",
   "grp": null
 }
]

在這種情況下，提供的解決方案會返回錯誤：

$ jq -jr '.[]|"name:", " ",.name, "\n","groups:", (.grp[]|" ",.name),"\n"' test_json2
name: cust1
jq: error (at test_json2:6): Cannot iterate over null (null)

任何解決方法表示讚賞。

使用“加入”，-j

$ jq -jr '.[]|"name:", " ",.name, "\n","groups:", (.grp[]|" ",.name),"\n"' test_json
name: cust1
groups: BA2 GA1 NA1 TR3 TS1

並帶有一個佔位符

$ jq -jr '.[]|"name:", " ",.name, "\n","groups:", (.grp//[{"name":"-"}]|.[]|" ",.name),"\n"' test_json
name: cust1
groups: -

$ jq -r '.[] |
     [ "name:", .name ], [ "groups:", .grp[].name ]
     | @tsv' file.json
name:   cust1
groups: BA2     GA1     NA1     TR3     TS1

也就是說，給出@tsv兩個數組，一個帶有名稱，一個帶有組。每個數組將成為自己的行。

如果grp數組可能為空，而您想插入 a-代替：

$ jq -r '.[] |
     [ "name:", .name ], [ "groups:", (.grp // [])[].name // "-" ]
     | @tsv' file.json
name:   cust1
groups: -

操作x // y返回x，除非x計算結果為null或false在這種情況下返回y。

這也將處理grp完全失去的情況（不僅僅是一個空數組）。

引用自：https://unix.stackexchange.com/questions/451496