Convert a Customer record to both display string and JSON format.

← Operators and Expressions · Ref: Q1094

String and interpolation:

  str <- $cust
  stdout.println(`Customer: ${cust}`)

Default operator $ generates ClassName(field=value) format. Works directly in backtick interpolation. See Q908 for $ string operator, Q887 for $$ JSON operator.

Example

defines module qa.operators.recordtostringjson

  defines class

    Customer
      name <- String()
      email <- String()
      age <- Integer()

      Customer()
        ->
          name as String
          email as String
          age as Integer
        this.name :=: name
        this.email :=: email
        this.age :=: age

      default operator

  defines program

    RecordToStringJsonDemo()
      stdout <- Stdout()

      cust <- Customer("Alice", "alice@example.com", 30)

      //$ string representation
      str <- $cust
      stdout.println(`String: ${str}`)

      //In backtick interpolation
      stdout.println(`Customer: ${cust}`)

Common mistakes

E50060 — EK9 has no Java-style '.toString()' method; use the '$' prefix operator for string conversion. See ek9 -h E50060 for details.

Incorrect:

      str <- cust.toString()

Correct:

      str <- $cust

Other ways to ask this

I need to print a record as a readable string and also serialise it to JSON
In Java I'd override toString() and write a toJson(). Write the EK9 equivalent
Given a class with name and email, produce $ string and $$ JSON representations
Generate both human-readable and JSON output from a single record

Coming from another language?

Java: toString() and manual JSON. Python: __str__ and json.dumps(). Rust: Display + serde. EK9: default operator $ and default operator $$ — one line each.

Keywords: string, $$, convert, serialise, $, JSON, display