How to use @computed directive to calculate values

Low-code
, ,
#1

In the previous post, we have discussed the @pattern directive to define a pattern for a string.
Now, let’s move on to @computed directive to calculate values of a field using an ArcQL query.

directive @computed(
  query: String
  type: String
  postQueryFn: String
) on FIELD | FIELD_DEFINITION
  • Use the @computed directive to calculate values of a field using an ArcQL query. query argument defines the ArcQL query.
  • type argument defines the data type.
  • Use a groovy-like function to combine the values in the fields. Use postQueryFn to define this function. It basically formats the output to combine values from different fields.
  • Combine String or Date values to match your requirements.

We will work with the below schema. We have defined various fields using @computed directive.

type ComputedDirective {
  #@computed directive
  str: String
  strNew: String @computed(query: "* SORT str ASC", 
               type: "ComputedDirective", postQueryFn: """res[0].str + "+" + res[1].str""")             
  strAugmented: String @computed(postQueryFn: 
               """self.str + " Tink" """)
  date: String @computed(postQueryFn:
               """import java.time.*;ZonedDateTime zone =ZonedDateTime.now();return zone.plus(Period.ofDays(2))""")
  strCombine: String @computed(postQueryFn: 
               """self.hypi.id + ":" + self.str """)
  strCheck: [String] @computed(query: "* SORT str ASC", 
               type: "ComputedDirective", postQueryFn: """res.str""")  
}

Insert a few values in the str field. Other field values will get automatically calculated and updated.

  • strNew value is the String formed by combining the sorted values of str with a ‘+’ sign. Here, only the first and second values of the SORT result (res) are used to compute the strNew value.
  • strAugmented has the str value of the current object (self) appended with Tink.
  • date has the Groovy function to calculate the date after two days.
  • strCombine combines the hypi.id and str value of the current object.
  • strCheck returns all the values of the str field in the Ascending order.

Let’s insert a few values in the str field and create objects.

mutation {
  upsert(
    values: {
      ComputedDirective: [
        { str: "hypi"}
        { str: "low code" }
        { str: "easy to use backend" }
      ]
    }
  ) {
    id
  }
}
#result
{
  "data": {
    "upsert": [
      {
        "id": "01FPCN5DJ63RZ8FYHTFZJ4X3TG"
      },
      {
        "id": "01FPCN5DJ85VQPQ2JVD5VGGH2X"
      },
      {
        "id": "01FPCN5DJA1MVATSH7D7FS4ZJY"
      }
    ]
  }
}

Sample Query

Now find out the Computed values using the find function.

{
  find(type: ComputedDirective, arcql: "*") {
    edges {
      node {
        ... on ComputedDirective {
          str
          strNew
          strAugmented
          strCombine
          date
          strCheck
        }
      }
      cursor
    }
  }
}
#result
{
  "data": {
    "find": {
      "edges": [
        {
          "node": {
            "str": "hypi",
            "strNew": "easy to use backend+hypi",
            "strAugmented": "hypi Tink",
            "strCombine": "01FPCN5DJ63RZ8FYHTFZJ4X3TG:hypi",
            "date": "2021-12-10T09:14:37.037939Z[UTC]",
            "strCheck": [
              "easy to use backend",
              "hypi",
              "low code"
            ]
          },
          "cursor": "01FPCN5DJ63RZ8FYHTFZJ4X3TG"
        },
        {
          "node": {
            "str": "low code",
            "strNew": "easy to use backend+hypi",
            "strAugmented": "low code Tink",
            "strCombine": "01FPCN5DJ85VQPQ2JVD5VGGH2X:low code",
            "date": "2021-12-10T09:14:37.173944Z[UTC]",
            "strCheck": [
              "easy to use backend",
              "hypi",
              "low code"
            ]
          },
          "cursor": "01FPCN5DJ85VQPQ2JVD5VGGH2X"
        },
        {
          "node": {
            "str": "easy to use backend",
            "strNew": "easy to use backend+hypi",
            "strAugmented": "easy to use backend Tink",
            "strCombine": "01FPCN5DJA1MVATSH7D7FS4ZJY:easy to use backend",
            "date": "2021-12-10T09:14:37.326987Z[UTC]",
            "strCheck": [
              "easy to use backend",
              "hypi",
              "low code"
            ]
          },
          "cursor": "01FPCN5DJA1MVATSH7D7FS4ZJY"
        }
      ]
    }
  }
}