If function means that for each occurrence of the loop, check the condition before generating an output.

If is more like a toggle for the mapping. The transformation evaluates the If expression, and if this expression is true, it will apply the mapping. But if it is false, the mapping will not be applied and the target element of the mapping will even not be created.

You can for example create a specific target element only if the value of a source element equals MyValue: “ .='MyValue'”

If will only create the target element if the expression is validated, but will not change the value of the mapping.

The If function is used to test a condition before doing the mapping and generating the output.

You can add a If function as an Xpath expression to any mapping rule to condition the execution of this mapping rule, that is to decide if the mapping is performed or not on the input data. Note that the If function does not always return an element, if the filtering condition is not met, the mapping is not performed and so no output is generated.

The If function will only create the target element if the expression is validated, but will not change the value of the mapping.

The If can be used on any element as illustrated in the following examples.

If example on a value node

In the following example, the node mapping is tested on the Price value and the mapping output is generated only if it is greater than 12 (Xpath filter expression is ' .>12 ').

Input csv file:

Code, Quantity, Price
A23, 2, 12.5
A24, 3, 10.0
A25, 1, 15.2
A26, 2, 13.6

Figure 2.47. If example mapping

In the second ligne, the Price is lower than the test value and the mapping output will be empty. Note that the output is not generated and so the separating comma is not present (as opposed to Filter function output).

Output csv file:

Code, Quantity, Price
A23, 2, 12.5
A24, 3
A25, 1, 15.2
A26, 2, 13.6

If example on a loop node

Doing a test on a loop node will condition the whole loop generation or not. The previous example is not very meaningful in this case. A loop is not conditionned to its own elements but can be conditionned to an external element such as a date or a general value as in the following example.

In the following example, the entire loop mapping is filtered on the Type of Invoice value and the mapping of the entire loop is performed only if this value is equal to 'AAA' (Xpath filter expression is ' csv/line[1]/field[1]='AAA' ').

Figure 2.48. If example mapping

The following input csv file (the same as in the previous example, but with an additional 'invoice' line) is used as input:

Code, Quantity, Price
AAA, 001, 25/09/2009
A23, 2, 12.5
A25, 1, 15.2
A26, 2, 13.6

The hereover Xpath condition, as it is met by the input file, will generate the following output file, including the complete loop data:

Code, Quantity, Price
A23, 2, 12.5
A25, 1, 15.2
A26, 2, 13.6

If the hereover Xpath condition is modified such as it is not met anymore by the input file, the loop data will not be generate and the output file woul simply be:

Code, Quantity, Price