Is there a DataWeave 1.0 "for" operator?

Question

I would like to create as many elements as a count variable specifies, for example:

There is a table that has information about supported equipment

select port_count 
from equipment
where id=#[flowVars.equipmentId]

And I've to generate a message that another system out of my control interprets and executes:

<dw:transform-message doc:name="Get value">
    <dw:set-payload><![CDATA[%dw 1.0
%output application/json
---
{
  "actions": {
    (for 1..flowVars.port_count map {
      "action": {
        "type": "add_port",
        "id": $$
      }
    })
  }
}]]></dw:set-payload>
</dw:transform-message>

Desired result:

{
  "actions": {
    "action": {
        "type": "add_port",
        "id": 1
    },
    "action": {
        "type": "add_port",
        "id": 2
    }
  }
}

aled aled · Accepted Answer · 2019-08-16T01:27:49

DataWeave has no concept of for because it is a functional language. Still you can what you want by using a range instead:

%dw 1.0
%var port_count=3
%output application/json
---
{
  actions: 
    (((1 to port_count) when port_count > 0 otherwise []) map
      action: {
        "type": "add_port",
        "id": $
      }
    )  reduce ($$ ++ $)
}

Output:

{
  "actions": {
    "action": {
      "type": "add_port",
      "id": 1
    },
    "action": {
      "type": "add_port",
      "id": 2
    },
    "action": {
      "type": "add_port",
      "id": 3
    }
  }
}

Just change the port_count variable for the flowVar and you will be all set.

Removing the reduce() operator will return a list instead, which would make more sense to me.

Is there a DataWeave 1.0 "for" operator?

1 Answers