WSPatch

In order to partially update an existing resource, you define the WSPatch attribute.

Syntax

WSPatch

Usage

You use this attribute to specify the action of the HTTP verb PATCH to partially update an existing resource. For instance, when you need to update the full resource, you use WSPut. When you just want to update a single field in a resource, you use WSPatch. The PATCH method is described in rfc5789 (external link).

You set the WSPatch attribute in the ATTRIBUTES() clause of the function.

An output message body is not allowed in the response, so returns must be specified as headers with the WSHeader attribute.

Example using WSPatch to push partial resource change

In this sample REST function a user email address is updated. In the function's id parameter the attribute WSParam specifies the user to update, and the newEmail parameter contains the value to update. The newEmail data is passed in the message body in either JSON or XML format.

A string is returned as a header. It is specified with a WSHeader attribute.

WSThrows is set to handle errors. In the TRY/CATCH block, the sqlca record is checked after the execution of the SQL query. The SQLERRMESSAGE is set to the message field of the userError variable, and a call to SetRestError() returns the message defined in WSThrows for the error. 

IMPORT com

PUBLIC DEFINE userError RECORD ATTRIBUTES(WSError = "User error")
  message STRING
END RECORD

PUBLIC FUNCTION UpdateUserProfile(
   id STRING ATTRIBUTE(WSParam), newEmail STRING)
   ATTRIBUTES(WSPatch,
              WSPath = "/users/{id}",
              WSDescription = "Update user email address",
              WSThrows = "400:@UserError,404:no user found")
   RETURNS STRING ATTRIBUTE (WSHeader)
   DEFINE ret STRING
    TRY
      UPDATE users SET email = newEmail
        WHERE @id  = id
       IF sqlca.sqlerrd[3] = 1 THEN # sqlerrd[3] indicates processed rows
         LET ret = SFMT("Updated user with ID: %1",id)
       ELSE
         CALL com.WebServiceEngine.SetRestError(404,NULL)
       END IF
    CATCH
       LET ret=SFMT("Error updating user with ID: %1",id)     
       LET userError.message = SFMT("SQL error:%1 [%2]",
                                    sqlca.sqlcode, SQLERRMESSAGE)
       CALL com.WebServiceEngine.SetRestError(400,userError)
    END TRY
    RETURN ret

 END FUNCTION