解析 jq returns null

Question

我有一个json输出

{
    "7": [
        {
            "devices": [
                "/dev/sde"
            ],
            "name": "osd-block-dcc9b386-529c-451e-9d84-8ccc4091102b",
            "tags": {
                "ceph.crush_device_class": "None",
                "ceph.db_device": "/dev/nvme0n1p5",
                "ceph.wal_device": "/dev/nvme0n1p6",
            },
            "type": "block",
            "vg_name": "ceph-c4de9e90-853e-4569-b04f-8677ef9a8c7a"
        },
        {
            "path": "/dev/nvme0n1p5",
            "tags": {
                "PARTUUID": "69712eb4-be52-4618-ba46-e317d6d3d76e"
            },
            "type": "db"
        }
    ],
    "41": [
        {
            "devices": [
                "/dev/nvme1n1p13"
            ],
            "name": "osd-block-97bce07f-ae98-4fdb-83a9-9fa2f35cee60",
            "tags": {
                "ceph.crush_device_class": "None",
            },
            "type": "block",
            "vg_name": "ceph-c1d48671-2a33-4615-95e3-cc1b18783f0c"
        }
    ],
    "9": [
        {
            "devices": [
                "/dev/sdf"
            ],
            "name": "osd-block-35323eb8-17c1-460d-8cc5-565f549e6991",
            "tags": {
                "ceph.crush_device_class": "None",
                "ceph.db_device": "/dev/nvme0n1p7",
                "ceph.wal_device": "/dev/nvme0n1p8",
            },
            "type": "block",
            "vg_name": "ceph-9488e8b8-ec18-4860-93d3-6a1ad91c698c"
        },
        {
            "path": "/dev/nvme0n1p7",
            "tags": {
                "PARTUUID": "ef0e9588-2a20-4c2c-8b62-d73945e01322"
            },
            "type": "db"
        }
    ]
}

要求输出：

osd.7 /dev/sde /dev/nvme0n1p5 /dev/nvme0n1p6
osd.41 /dev/nvme1n1p13 n/a n/a
osd.9 /dev/sdf /dev/nvme0n1p7 /dev/nvme0n1p7

问题： 当我尝试使用 jq .[][].devices 进行解析时，我得到空值：

$ cat json | jq .[][].devices
[
  "/dev/sde"
]
null
[
  "/dev/nvme1n1p13"
]
null
[
  "/dev/sdf"
]
null

我可以通过jq .[][].devices[]?解决。

但是，当我确实想查看没有价值的地方时，这个技巧对我没有帮助（改为打印 n/a）：

$ cat json | jq '.[][].tags | ."ceph.db_device"'
"/dev/nvme0n1p5"
null
"/dev/nvme0n1p3"
null
null
"/dev/nvme0n1p7"
null

最后，我尝试创建一个 table:

$ cat json | jq -r '["osd."+keys[]], [.[][].devices[]?], [.[][].tags."ceph.db_device" // ""] | @csv' | column -t -s,
"osd.7"           "osd.41"          "osd.9"
"/dev/sde"        "/dev/nvme0n1p13" "/dev/sdf"
"/dev/nvme0n1p5"  "/dev/nvme0n1p7"

所以明显的问题是第 3 行不匹配正确的值。

最后一个问题是如何将它从列转为行，如所需输出中所述？

Answer 1

这会如你所愿吗？

jq --raw-output '
  to_entries[] | [
    "osd." + .key,
    ( .value[0]
    | .devices[],
      ( .tags
      | ."ceph.db_device" // "n/a",
        ."ceph.wal_device" // "n/a"
      )
    )
  ]
  | @tsv
'

osd.7   /dev/sde    /dev/nvme0n1p5  /dev/nvme0n1p6
osd.41  /dev/nvme1n1p13 n/a n/a
osd.9   /dev/sdf    /dev/nvme0n1p7  /dev/nvme0n1p8

Demo

解析 jq returns null

parsing jq returns null

null

json

jq