E07800: Web Service must have return value and it must be compatible with HTTPResponse

What went wrong

A service method is missing a return statement.

Worked examples

Compilable examples demonstrating this error and the correct fix:

• ek9 -q 869 (Why must all EK9 service methods declare a return value?)

How to fix it

1. Add return statement with HTTPResponse

Common causes

• Forgot to return HTTPResponse
• Incomplete implementation

See also

• E07800: service method missing return (this error)
• E07750: service method wrong return type

Examples

Every example is compiled by the EK9 compiler: the first fails exactly as captioned, the others fix it.

Fails with E07800: Web Service must have return value and it must be compatible with HTTPResponse

#!ek9
defines module error.e07800.bad

  defines class

    TextResponse with trait of HTTPResponse
      text as String?

      default private TextResponse()

      TextResponse()
        -> body as String
        this.text: body

      override contentType() as pure
        <- rtn as String: "text/plain"

      override content()
        <- rtn as Bytes: Bytes().withUtf8(text)

      override status() as pure
        <- rtn as Integer: 200

      default operator ?

  defines service

    Addresses for :/addresses open

      //A service method answers every request
      byId() as GET for :/{id}
        -> id as String
        stdout <- Stdout()
        stdout.println(id)

Fixed: Declare the HTTPResponse it returns

#!ek9
defines module error.e07800.good

  defines class

    TextResponse with trait of HTTPResponse
      text as String?

      default private TextResponse()

      TextResponse()
        -> body as String
        this.text: body

      override contentType() as pure
        <- rtn as String: "text/plain"

      override content()
        <- rtn as Bytes: Bytes().withUtf8(text)

      override status() as pure
        <- rtn as Integer: 200

      default operator ?

  defines service

    Addresses for :/addresses open

      byId() as GET for :/{id}
        -> id as String
        <- response as HTTPResponse: TextResponse(`address ${id}`)

Questions and answers

These Q&A entries show E07800 and its fix:

• Q869: Why must all EK9 service methods declare a return value?