Creating new fields

You can use a Compute node to create a new output message by adding new fields to an existing input message.

About this task

This topic provides example ESQL code for a Compute node that creates a new output message based on the input message, to which are added a number of additional fields.

The input message that is received by the Compute node within the message flow is an XML message, and has the following content:

<TestCase description="This is my TestCase">
    <Identifier>ES03B305_T1</Identifier>
    <Sport>Football</Sport>
    <Date>01/02/2000</Date>
    <Type>LEAGUE</Type>
</TestCase>

The Compute node is configured and an ESQL module is created that includes the following ESQL. The following code copies the headers from the input message to the new output message, then creates the entire content of the output message body. For more information about the CREATE statement, see CREATE statement.

-- copy headers 
DECLARE i INTEGER 1;
DECLARE numHeaders INTEGER CARDINALITY(InputRoot.*[]);

WHILE i < numHeaders DO
    SET OutputRoot.*[i] = InputRoot.*[i]; 
    SET i = i + 1; 
END WHILE;

CREATE FIELD OutputRoot.XMLNS.TestCase.description TYPE NameValue VALUE 'This is my TestCase';
CREATE FIRSTCHILD OF OutputRoot.XMLNS.TestCase Domain('XMLNS') NAME 'Identifier' 
                                VALUE InputRoot.XMLNS.TestCase.Identifier;
CREATE LASTCHILD OF OutputRoot.XMLNS.TestCase Domain('XMLNS') NAME 'Sport' 
                                VALUE InputRoot.XMLNS.TestCase.Sport;
 CREATE LASTCHILD OF OutputRoot.XMLNS.TestCase Domain('XMLNS') NAME 'Date' 
                                VALUE InputRoot.XMLNS.TestCase.Date;
 CREATE LASTCHILD OF OutputRoot.XMLNS.TestCase Domain('XMLNS') NAME 'Type' 
                                VALUE InputRoot.XMLNS.TestCase.Type;
 CREATE FIELD OutputRoot.XMLNS.TestCase.Division[1].Number TYPE NameValue 
                                VALUE 'Premiership';
 CREATE FIELD OutputRoot.XMLNS.TestCase.Division[1].Result[1].Number TYPE NameValue VALUE  '1';
 CREATE FIELD OutputRoot.XMLNS.TestCase.Division[1].Result[1].Home TYPE Name;
 CREATE LASTCHILD OF OutputRoot.XMLNS.TestCase.Division[1].Result[1].Home NAME 'Team' 
                                VALUE 'Liverpool' ;
 CREATE LASTCHILD OF OutputRoot.XMLNS.TestCase.Division[1].Result[1].Home NAME 'Score' 
                                VALUE '4';
 CREATE FIELD OutputRoot.XMLNS.TestCase.Division[1].Result[1].Away TYPE Name;
 CREATE LASTCHILD OF OutputRoot.XMLNS.TestCase.Division[1].Result[1].Away NAME 'Team' 
                                VALUE 'Everton';
 CREATE LASTCHILD OF OutputRoot.XMLNS.TestCase.Division[1].Result[1].Away NAME 'Score' 
                                VALUE '0';

 CREATE FIELD OutputRoot.XMLNS.TestCase.Division[1].Result[2].Number TYPE NameValue VALUE '2';
 CREATE FIELD OutputRoot.XMLNS.TestCase.Division[1].Result[2].Home TYPE Name;
 CREATE LASTCHILD OF OutputRoot.XMLNS.TestCase.Division[1].Result[2].Home NAME 'Team' 
                                VALUE 'Manchester United';
 CREATE LASTCHILD OF OutputRoot.XMLNS.TestCase.Division[1].Result[2].Home NAME 'Score' 
                                VALUE '2';
 CREATE FIELD OutputRoot.XMLNS.TestCase.Division[1].Result[2].Away TYPE Name;
 CREATE LASTCHILD OF OutputRoot.XMLNS.TestCase.Division[1].Result[2].Away NAME 'Team' 
                                VALUE 'Arsenal';
 CREATE LASTCHILD OF OutputRoot.XMLNS.TestCase.Division[1].Result[2].Away NAME 'Score' 
                                VALUE '3';

 CREATE FIELD OutputRoot.XMLNS.TestCase.Division[2].Number TYPE NameValue 
                                VALUE '2';
 CREATE FIELD OutputRoot.XMLNS.TestCase.Division[2].Result[1].Number TYPE NameValue 
                                VALUE  '1';
 CREATE FIELD OutputRoot.XMLNS.TestCase.Division[2].Result[1].Home TYPE Name;
 CREATE LASTCHILD OF OutputRoot.XMLNS.TestCase.Division[2].Result[1].Home NAME 'Team' 
                                VALUE 'Port Vale';
 CREATE LASTCHILD OF OutputRoot.XMLNS.TestCase.Division[2].Result[1].Home NAME 'Score' 
                                VALUE '9' ;
 CREATE FIELD OutputRoot.XMLNS.TestCase.Division[2].Result[1].Away TYPE Name;
 CREATE LASTCHILD OF OutputRoot.XMLNS.TestCase.Division[2].Result[1].Away NAME 'Team' 
                                VALUE 'Brentford';
 CREATE LASTCHILD OF OutputRoot.XMLNS.TestCase.Division[2].Result[1].Away NAME 'Score' 
                                VALUE '5';

The output message that results from the ESQL shown above has the following structure and content:

<TestCase description="This is my TestCase">
  <Identifier>ES03B305_T1</Identifier>
  <Sport>Football</Sport>
  <Date>01/02/2000</Date>
  <Type>LEAGUE</Type>
  <Division Number="Premiership">
    <Result Number="1">
      <Home>
        <Team>Liverpool</Team>
        <Score>4</Score>
      </Home>
      <Away>
        <Team>Everton</Team>
        <Score>0</Score>      
      </Away>
    </Result>
    <Result Number="2">
      <Home>
        <Team>Manchester United</Team>
        <Score>2</Score>
      </Home>
      <Away>
        <Team>Arsenal</Team>
        <Score>3</Score>      
      </Away>
    </Result>
  </Division>
  <Division Number="2">
    <Result Number="1">
      <Home>
        <Team>Port Vale</Team>
        <Score>9</Score>
      </Home>
      <Away>
        <Team>Brentford</Team>
        <Score>5</Score>      
      </Away>
    </Result>
  </Division>
</TestCase>