- Class Parameters: Syntax and Usage

Syntax

??>

A class parameter is in the following format:

??>FULL_CLASS_NAME|METHOD_NAME|METHOD_PARAM1|METHOD_PARAM2 …

So a class parameter which calls the method util.Census.getPopulation(String city, String state) might look like this:

??>util.Census|getPopulation|Boston|Massachusetts

Whitespace characters cannot be included in a parameter unless the parameter’s value is enclosed in double quotes:

??>util.Census|getPopulation|Boston|Massachusetts|”United States”

If a parameter’s value should include an actual double quote then it needs to be escaped with the backslash character:

??util.MyClass|myMethod|”This is a double quote: \””|”This is a dollar sign: $”|

Usage

When a class parameter appears in the code of an SQLOperation, it is replaced with its value before it is sent to the database.

So if an operation’s SQL was:

SELECT * FROM SCHEM.CITIES WHERE CITY_POP > ??>util.Census|getPopulation|Boston|Massachusetts

Then the SQL which would actually be sent to the database would be:

SELECT * FROM SCHEM. CITIES WHERE CITY_POP > 645000

Class parameters are never displayed as prompts to the user.

Class parameters can also be used in the operation instructions. Placing the text:

Population of Boston, MA is ??>util.Census|getPopulation|Boston|Massachusetts

...in the operation instructions would result in the instructions reading:

Population of Boston, MA is 645000

Running Operations from Class Parameters

WOW has a built in class named RunOp for running SQL queries from class parameters.

This allows you to run one operation and place its results into the SQL of another operation.

RunOp/getValue

The getValue method of RunOp will run an operation and return a single value. For example, if this was the SQL of operation 110:

SELECT CITY_POP FROM SCHEM.CITYDATA WHERE CITY_NAME = ‘Boston’ AND CITY_STATE = ‘MA’

...then in a different operation you could use this SQL to select names of cities with a greater population than Boston:

SELECT CITY_NAME FROM SCHEM.CITYDATA WHERE CITY_POP > ??>RunOp|getValue|110

In this example, both operations queried the same table, however they could be querying two different tables on two completely different databases.

RunOp|getValue will always give the value from the first column of the first record in the results.

RunOp/getSQLValue

RunOp|getSQLValue works in much the same way as RunOp|getValue, however

the value it returns will be formatted for inclusion in SQL. For example character

values returned by getSQLValue will be wrapped in single quotes; characters

values returned by RunOp|getValue will not be wrapped in quotes.

RunOp/buildInClause

RunOp|buildInClause can be used to build a SQL IN clause based on the results of an operation.

The syntax for RunOp|buildInClause is as follows:

??>RunOp|buildInClause|<Operation ID>|<Prefix>

Consider the Account table:

Operation #220 has SQL which selects the IDs of accounts which are overdue:

SELECT ID FROM SCHEM.ACCOUNTS WHERE OVERDUE = ‘Y’

A different operation could use the results of operation #220 to calculate the total balance on all accounts that are overdue:

SELECT SUM(BALANCE) FROM SCHEM.ACCOUNTS WHERE ??>RunOp|buildInClause|220|”ID IN”

That will result in the following SQL being sent to the DB:

SELECT SUM(BALANCE) FROM SCHEM.ACCOUNTS WHERE ID IN (1, 4, 5)

RunOp|buildInClause takes an optional third parameter, which is the SQL to generate when there are no values returned by the executed operation.

For example:

SELECT SUM(BALANCE) FROM SCHEM.ACCOUNTS WHERE ??>RunOp|buildInClause|220|”ID IN”|”1 = 2”

If the above SQL is run, and operation 220 does not return any results, then the SQL sent to the database would be:

SELECT SUM(BALANCE) FROM SCHEM.ACCOUNTS WHERE 1 = 2

Run an operation and include the whole HTML generation:

??>RunOp|getOperation|2246

This will execute WOW Operation with ID = 2246 and generate and return the operations HTML.

NOTE: This feature should only be used in limited READ ONLY scenarios.

TAGS: Run an operation and generate HTML, include operation HTML