In the Transformations tab, you can define a transformation by simple drag and drop.

You can map fields between multiple input and output ports. In all components both input and output ports are numbered starting from 0.

You can easily recognize which fields are mapped. The mapped fields become bold.

To design a simple one-to-one mapping, drag fields from the left hand pane to the right hand pane. If you drop the field onto an output field, you create a mapping. The middle part of the dialog is filled in automatically to the expression like: $in.portnumber.fieldname.

If you need to map input record fields to output record fields with a same name, drag and drop the whole record. The middle part of the dialog will contain: $in.portnumber.*.

To map more input fields to one output field or to apply a CTL function on the field value you need the middle pane. Drag and drop input field(s) to a field in the middle pane, use function(s), sequences or dictionary values and drag and drop the middle pane field onto right pane field.

For example, if you want to concatenate values of various fields you drag and drop all fields to be concatenated the same row in the Transformations pane. Expression similar to $in.portnumber1.fieldnameA+$in.portnumber1.fieldnameB appears. The input fields can come from different input ports (in the case of Joiners and the DataIntersection component).

Whenever the mapping is correct, the corresponding circle is filled in with blue.

If you drop input field into a blank space of the right hand pane (between two fields), you will just copy input metadata to the output. Metadata copying is a feature which works only within a single port.

You can also copy any input field to the output by right-clicking the input field item in the left pane and selecting Copy fields to... and the name of the output metadata:

Remember that if you have not defined the output metadata before defining the transformation, you can define them even here by copying and renaming the output fields using right-click. However, it is much simpler to define new metadata prior to defining the transformation.

If you defined the output metadata using this Transform editor, you would be informed that output records are not known and you would have to confirm the transformation with this error and (after that) specify the delimiters in metadata editor.

	Note
	Fields of output metadata can be rearranged by a simple drag and drop with the left mouse button.

If you select any item in the left, middle or right pane, corresponding items will be connected by lines. See example below:

Figure 39.3. Mapping of Inputs to Outputs (Connecting Lines)

You can write the desired transformation:

Figure 39.4. Editor with Fields and Functions

Transform editor supports wildcards in mapping. If you right click a record or one of its fields, click Map record to and select a record, you will produce a transformation like this (as observed in the Source tab): $out.0.* = $in.1.*;, meaning "all output fields of record number 0 are mapped to all input fields of record number 1". In Transformations, wildcard mapping looks like this:

Figure 39.5. Input Record Mapped to Output Record Using Wildcards

If you want to create a new Java transform class, press the Java Transform Wizard button. The following dialog will open:

Figure 39.7. Java Transform Wizard Dialog

After you click the Finish button, information about the transform result appears.

Figure 39.8. Info after Java Transform Wizard Dialog

The Source folder field will be mapped to the project ${TRANS_DIR}, for example SimpleExamples/trans. A new transform class can be created by entering the Name of the class and, optionally, the containing Package and pressing the Finish button. The newly created class will be located in the Source folder.

If you click the Open tab, the second button in the upper right corner of the Transform editor, a new tab with the CTL source code of the transformation will be opened in the Graph Editor with a notification as shown below:

Figure 39.9. Confirmation Message

The new tab is opened at the same level as Graph and Source.

Figure 39.10. Transformation Definition in CTL (Transform Tab of the Graph Editor)

If you switch to this tab, you can view the declared variables and functions in the Outline pane.

Functions and variables are displayed in the Outline.

The tab can be closed by clicking the red cross in the upper right corner of the tab.

Content Assist helps you choosing the proper field, variable or function.

Content assist is made active by pressing Ctrl+Space.

If you press these two keys inside any of the expressions, the help advises what should be written to define the transformation.

Figure 39.11. Content Assist (Record and Field Names)

If you press these two keys outside any of the expressions, the help offers a list of functions that can be used to define the transformation.

Figure 39.12. Content Assist (List of CTL Functions)

If you have an error in your definition, a red circle with a white cross appears on the corresponding line followed by a more detailed information at the lower left corner.

If you want to convert the transformation code into the Java language, click the Convert to Java button.

Figure 39.13. Transformation Definition in Java

Remember also that you can define your own error messages by defining the last function: getMessage(). It returns strings that are written to console. More details about transformations in each component can be found in the sections in which these components are described.

Important

Remember that the getMessage() function is only called from within functions that return integer data type. To allow calling this function, you must add return statement(s) with values less than or equal to -2 to the functions that return integer. For example, if any of the functions like transform(), append() or count(), etc. returns -2, getMessage() is called and the message is written to Console.