Editing invidual expressions - 7.1

Talend Real-time Big Data Platform Studio User Guide

author
Talend Documentation Team
EnrichVersion
7.1
EnrichProdName
Talend Real-Time Big Data Platform
task
Design and Development
EnrichPlatform
Talend Studio

About this task

The following example shows how to use the Expression Builder to edit two indiviual expressions.

In this example, two input flows are connected to the tMap component.

  • From the DB input, comes a list of names made of a first name and a last name separated by a space char.

  • From the File input, comes a list of US states, in lower case.

In the tMap, use the expression builder to: First, replace the blank char separating the first and last names with an underscore char, and second, change the states from lower case to upper case.

Procedure

  1. In the tMap, set the relevant inner join to set the reference mapping.
    For more information regarding tMap, see tMap operation and Map editor interfaces.
  2. From the main (row1) input, drop the Names column to the output area, and the State column from the lookup (row2) input towards the same output area.
  3. Click in the first Expression field (row1.Name), and then click the ... button that appears next to the expression.

    The Expression Builder dialog box opens up.

  4. In the Category area, select the relevant action you want to perform. In this example, select StringHandling and select the EREPLACE function.
  5. In the Expression area, paste row1.Name in place of the text expression, in order to get: StringHandling.EREPLACE(row1.Name," ","_"). This expression will replace the separating space char with an underscore char in the char string given.
    Note that the CHANGE and EREPLACE functions in the StringHandling category are used to substitute all substrings that match the given regular expression in the given old string with the given replacement and returns a new string. Their three parameters are:
    oldStr
    the old string
    newStr
    the regular expression to match
    replacement
    the string to be substituted for every match
  6. Now check that the output is correct, by typing in the relevant Value field of the Test area, a dummy value, e.g: Chuck Norris and clicking Test!. The correct change should be carried out, for example, Chuck_Norris.
  7. Click OK to validate the changes, and then proceed with the same operation for the second column (State).
  8. In the tMap output, select the row2.State Expression and click the [...] button to open the Expression builder again.

    This time, the StringHandling function to be used is UPCASE. The complete expression says: StringHandling.UPCASE(row2.State).

  9. Once again, check that the expression syntax is correct using a dummy Value in the Test area, for example indiana. The Test! result should display INDIANA for this example. Then, click OK to validate the changes.

    Both expressions are now displayed in the tMap Expression field.

Results

These changes will be carried out along the flow processing. The output of this example is as shown below.