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How to return specific item from Cloud Workflows instance?

I have the problem to get the data out of the JSON response instance. I am using Cloud Workflows to get the information about the current state of my VMs. I am using the the .get functions that returns this long JSON that is high structured, e.g. launchResult is returned as:

{
   "name":"some name",
   "status":"some status",
   "items":[
      {
         "key":"key1",
         "property1":"xxxx",
         "property2":"ccvdvdvd"
      },
      {
         "key":"key2",
         "property1":"xxxrerex",
         "property2":"ccvdveedvd"
      }
   ],
   "kind":"some kind"
}

I can return for example "some status", by ${launchResult.status}, even key1, as {launchResult.items[0].key}.

The question is: How can I do sth like launchResult.items["key" == "key1"].property1? I mean I want to return the property1 from the item based on the key.

Solution

  • To get the property from an item in an list of maps based on the value of another property of that map, I would suggest the following:

    • To iterate over the elements of the list until you get the one with the property you're looking for.

    This is a sample code I made to show how to use iterations along with conditionals in Cloud Workflows to achieve this:

    main:
  params: []
  steps:
  - define:
      assign:
        # Incremental variable set to zero
        - i: 0
        # Value to look up in list
        - cond: "key2"
        # A variable that contains a sample data as the JSON
        # showed in the question
        - test: 
            name: some name
            status: some status
            items:
            - key: "key1"
              property1: xxxx
              property2: ccvdvdvd
            - key: "key2"
              property1: xxxrerex
              property2: ccvdveedvd
            - key: "key3"
              property1: xxex
              property2: ccvdvffdvd
            kind: some kind
  - lookupInItems:
      switch:
        # Here we're looking for the element over the list test.items until the condition is met 
        # or the list ends
        - condition: ${i < len(test.items) and test.items[i].key!=cond}
        # If the condition is not met, keep iterating using iterate step
          next: iterate
      # If the element is found or the list ends, jumps to the read step
      next: read
  - iterate:
      assign: 
      # Increment the increment variable i
        - i: ${i+1}
      next: lookupInItems
  # If the iteration ends, check for the value
  - read:
      switch:
        # Check if the value was found
        # if this check is not made, an out of index error will occur when trying to show
        # the property of a value does not exists
        - condition: ${i < len(test.items)}
          next: found
      next: notfound
  # Print a message on the sys.log either the value was found or not
  - notfound:
      call: sys.log
      args:
        text: ${"Value " + cond + " not found in list"}
        severity: "WARNING"
      next: end
  - found:
      call: sys.log
      args:
        text: ${test.items[i].property1}
        severity: "INFO"
      next: end

    See also: