JoSQL User Manual - Expression Lists

Expression Lists

As of version 1.9 you can create a list of expressions using [] brackets.

For example:

SELECT *
FROM   MyObject
WHERE  findMin ([first, second, third, fourth]) > 1

In this case all the expressions between the [ and ] will be placed together into an ExpressionList (which is basically a wrapper around a

List).

The expression list can be used wherever a standard expression is used. When the expression list is evaluated JoSQL will evaluate each expression in the list and return a list of the values.

Nested Lists

It is also possible to create nested lists, for example:

SELECT *
FROM   MyObject
WHERE  findMin ([first, [second, second2, second3], third, [fourth, fourth2]]) > 1

Use in Functions

To use lists in functions just use a

List as the argument type:

public double findMin (List nums)

When the function is called the expressions are evaluated and a list created with those values and passed to the function.

If you wish to have more control over the execution of the expressions however you should use a ExpressionList or Expression as the argument type:

public double findMin (Expression nums)

In this case JoSQL will just pass the expression list itself and you should then use: getExpressions() to get the expressions to evaluate.

Examples

Use in SELECT Clause

SELECT [min, max]
FROM   MyObject

Use in WHERE Clause function

SELECT *
FROM   MyObject
WHERE  findMin ([first, last]) = :value

Use in SELECT Clause for new Object creation

SELECT new java.util.ArrayList ([first, last])
FROM   MyObject