[Bug] Summarizing on empty data should not return an error

[hyamanieu]

Describe the bug

Whether summarizing or not summarizing, if input is empty, it should return an empty value rather than throwing an error.
According to me, whether we:

• receive an input with several elements, but all element do not pass the set Filter
• or receive an input with no element
• or receive an input with no element, while not using the summarizing function

the same result shall be received: an empty Table.

This is important as we cannot know in advance if our API call will return an array with 0 or several elements. It also impacts the use within alerts.

Steps to reproduce

• Source: Inline
• Summarize: sum(value)
• Summarize by: group
• Filter : value > 100
• data: []

Result:

error getting data frame from inline data. summarize by field not found. Not applying summarize

I would expect the same result as follows:

• Source: inline
• Summarize: sum(value)
• Summarize by: group
• Filter : value > 100
• data :

[
  {
    "group": "A",
    "id": 1,
    "value": 42
  },
  {
    "group": "B",
    "id": 2,
    "value": 37
  },
  {
    "group": "A",
    "id": 3,
    "value": 28
  },
  {
    "group": "C",
    "id": 4,
    "value": 53
  },
  {
    "group": "B",
    "id": 5,
    "value": 19
  },
  {
    "group": "C",
    "id": 6,
    "value": 45
  },
  {
    "group": "A",
    "id": 7,
    "value": 32
  },
  {
    "group": "B",
    "id": 8,
    "value": 29
  },
  {
    "group": "C",
    "id": 9,
    "value": 61
  }
]

Result: <0 series returned> (aka empty table)

or for

• Source: Inline
• Filter : value > 100
• data: []

Result: <0 series returned> (aka empty table)

Version Details:

• Grafana version : 10.4.1
• Plugin version : 0.7.1

[digitalkristurner]

I have also had this issue and it trips me up often!