tHMap - 6.1

Talend Components Reference Guide

EnrichVersion
6.1
EnrichProdName
Talend Big Data
Talend Big Data Platform
Talend Data Fabric
Talend Data Integration
Talend Data Management Platform
Talend Data Services Platform
Talend ESB
Talend MDM Platform
Talend Open Studio for Big Data
Talend Open Studio for Data Integration
Talend Open Studio for Data Quality
Talend Open Studio for ESB
Talend Open Studio for MDM
Talend Real-Time Big Data Platform
task
Data Governance
Data Quality and Preparation
Design and Development
EnrichPlatform
Talend Studio

Warning

This component will be available in the Palette of Talend Studio on the condition that you have subscribed to one of the Talend Platform products.

tHMap properties

Component family

Processing

 

Function

tHMap transforms data from a wide range of sources to a wide range of destinations. If you want to use multiple inputs and/or outputs, you must use Talend Data Mapper I/O functions. For more information, see Talend Data Mapper User Guide.

Purpose

tHMap executes transformations (called maps) between different sources and destinations by harnessing the capabilities of Talend Data Mapper, available in the Mapping perspective.

Basic settings

Open Map Editor

Click the [...] button to open the tHMap Structure Generate/Select wizard where you can either have the hierarchical mapper structure generated automatically based on the schema, or select an existing hierarchical mapper structure. You must do this for both the input and output sides of your Map.

 

Map Path

Specifies the map to be executed.

If the map was automatically created using the wizard described above, this is path is set automatically.

If you want to use an existing map, click the [...] button next to the Map Path field to open a dialog box in which you can select the map you want to use, then click the [...] button next to Open Map Editor to work with the map selected. Note that this map must have previously been created in the Mapping perspective.

Read Input As

Select the radio button which corresponds to how you want the input to be read. Depending on your map, only some of the options may be available.

  • Data Integration columns (default): Use this option if you are working with Talend Data Integration metadata.

  • Single column: Use this option if you are working with Talend Data Mapper metadata.

Write Output As

Select the radio button which corresponds to how you want the output to be written. Depending on your map, only some of the options may be available.

  • Data Integration columns (default): Use this option if you are working with Talend Data Integration metadata.

  • String (single column): Use this option if the data in the output column is to be a String.

  • Byte array (single column): Use this option if the data in the output column is to be a Byte array.

  • InputStream (single column): Use this option if you are working with Talend Data Mapper metadata and the input data is a stream.

  • Document (single column); Use this option if the output column is to be a Document.

Advanced settings

Map Variable

In this field, enter a context variable that you can use to define the absolute path to a map file. This can be useful in cases where you want to use multiple maps without creating a new Job each time.

In the Contexts tab, the value must be an absolute path and the required items (Structures, Maps, and so on) must all be present in the same Talend project. This can be a different project from the current project, but everything must be present in the same project.

For further information on working with context variables, see Talend Studio User Guide.

Log Level

From the drop-down list, select how often you want events to be logged.

  • Infrequent: Logs only events related to startup, shutdown and exceptions.

  • Frequent (default): Logs events related to startup, shutdown and exceptions, and once per map execution.

  • Info: Logs all events at an informational level or higher.

  • All: Logs all events.

  • None: Logs nothing.

 

Exception Threshold

Talend Data Mapper returns an execution status with an severity value which can be OK, Info, Warning, Error or Fatal. By setting the exception threshold, you can specify the severity level at which an exception is thrown, thus enabling downstream components to detect the error in cases other than the default value of Fatal.

From the drop-down list, select the severity level at which an exception may be thrown during the execution of a map.

  • Fatal (default): An exception is thrown when a fatal error occurs.

  • Error: An exception is thrown when an error (or higher) occurs.

  • Warning: An exception is thrown when a warning (or higher) occurs.

Note that, in order to help you diagnose problems with your map, when you test the map in the Studio, any errors that occur which are at warning level or above will be printed in the console window, regardless of the setting of the Exception Threshold.

 tStatCatcher Statistics

Select this check box to gather the Job processing metadata at the Job level as well as at each component level.

Global Variables

ERROR_MESSAGE: the error message generated by the component when an error occurs. This is an After variable and it returns a string. This variable functions only if the Die on error check box is cleared, if the component has this check box.

EXECUTION_STATUS: the pointer to the ExecutionStatus object, which is returned whenever tHMap executes a Talend Data Mapper map. This is an After variable and it returns a string.

EXECUTION_SEVERITY: the Overall Severity numeric value. This is an After variable and it returns an integer.

A Flow variable functions during the execution of a component while an After variable functions after the execution of the component.

To fill up a field or expression with a variable, press Ctrl + Space to access the variable list and choose the variable to use from it.

For further information about variables, see Talend Studio User Guide.

Usage

tHMap is used for Jobs that require complex data mapping from a variety of different sources.

The input and output connections can use Talend Data Mapper metadata, Talend Data Integration metadata, or a combination of the two. Each connection is independent.

When you open the Map Editor for the first time for each connection, it either generates a Talend Data Mapper structure definition based on the schema of the Talend Data Integration component, or allows you to select an existing Talend Data Mapper structure if you are using Talend Data Mapper metadata. It then creates a map with the structure selected or generated.

This component can be used in several ways:

Limitation

n/a

Note

For further information about performing transformations using Talend Data Mapper, see Talend Data Mapper User Guide.

Scenario 1: Using Talend Data Mapper metadata

The following scenario creates a three-component Job, reading data from an input file that is transformed using a map that was previously created in the Mapping perspective and then outputting the transformed data in a new file. It works with Talend Data Mapper metadata.

Copying an editable version of the example files

  1. In the Mapping perspective, in the Data Mapper view, expand the Hierarchical Mapper node and the Other Projects folder, right-click Examples and then select Copy in the contextual menu.

  2. In the Data Mapper view, right-click at the root of the Hierarchical Mapper node, and then select Paste in the contextual menu.

    This copies an editable version of all the read-only example files to your local workspace.

Adding and linking the components

  1. In the Integration perspective, create a new Job and call it tdm_to_tdm.

  2. Click the point in the design workspace where you want to add the first component, start typing tFileInputRaw, and then click the name of the component when it appears in the list proposed in order to select it.

  3. Do the same to add a tHMap component and a tFileOutputRaw component as well.

  4. Connect the tFileInputRaw component to the tHMap component using a Row > Main link and rename it input, then connect the tHMap component to the tFileOutputRaw component using a Row > Main link and name it output. When you are asked if you want to get the schema of the target component, click Yes.

Defining the properties of tFileInputRaw

  1. Select the tFileInputRaw component to define its properties.

  2. In the Basic settings tab, click the [...] button next to the Filename field then browse to the location on your file system where the input file is stored, or enter the path manually between double quotes. For this example, use <PATH_TO_WORKSPACE>/<PROJECT_NAME>/Sample Data/CSV/PurchaseOrderPayPal/PayPalPO.csv.

  3. Set the Mode as Read the file as a string, and leave all the other parameters unchanged.

Defining the properties of tFileOutputRaw

  1. Select the tFileOutputRaw component to define its properties.

  2. In the Basic settings tab, click the [...] button then browse to the location on your file system where the output file is to be stored, or enter the path manually between double quotes. Leave the other parameters unchanged.

Defining the properties of tHMap

  1. Select the tHMap component to define its properties.

  2. Click the [...] button next to the Map Path field to open the picker and select the map to use, Maps/CSV/POPayPalCsv_PO2, then click OK. This map transforms a CSV file into an XML file.

  3. Check that Read Input As is set to Single Column.

  4. Check that Write Output As is set to String (single column).

Saving and executing the Job

  1. Press Ctrl+S to save your Job.

  2. In the Run tab, click Run to execute the Job.

  3. Browse to the location on your file system where the output file is stored to check that an XML file has been created containing the same data as the input CSV file.

Scenario 2: Using Talend Data Integration metadata

The following scenario creates a three-component Job, reading data from an input file that is transformed using a map that you create in the Mapping perspective and then outputting the transformed data in a new file. It works with Talend Data Integration metadata.

Copying an editable version of the example files

  1. In the Mapping perspective, in the Data Mapper view, expand the Hierarchical Mapper node and the Other Projects folder, right-click Examples and then select Copy in the contextual menu.

  2. In the Data Mapper view, right-click at the root of the Hierarchical Mapper node, and then select Paste in the contextual menu.

    This copies an editable version of all the read-only example files to your local workspace.

Adding and linking the components

  1. In the Integration perspective, create a new Standard Job and call it di_to_di.

  2. Click the point in the design workspace where you want to add the first component, start typing tFileInputDelimited, and then click the name of the component when it appears in the list proposed in order to select it.

  3. Do the same to add a tHMap component and a tFileOutputXML component as well.

  4. Connect the tFileInputDelimited component to the tHMap component using a Row > Main link, then connect the tHMap component to the tFileOutputXML component using a Row > Main link.

Defining the properties of tFileInputDelimited

  1. Select the tFileInputDelimited component to define its properties.

  2. In the Basic settings tab, click the [...] button next to the File name/Stream field then browse to the location on your file system where the input Excel file is stored, or enter the path manually between double quotes. For this example, use <PATH_TO_WORKSPACE>/<PROJECT_NAME>/Sample Data/CSV/PurchaseOrderPayPal/PayPalPO.csv.

  3. Select the CSV options check box.

  4. Change the Field Separator to a comma, between double quotes (",").

  5. Change the value of Header to 1.

  6. Click the [...] button next to Edit schema to define the schema.

  7. Add three columns and rename them txn_id, payment_date and first_name (which correspond to the names of the first three columns in the input file, and is sufficient for the purposes of this example), and then click OK.

  8. Leave all the other parameters unchanged.

Defining the properties of tFileOutputXML

  1. Select the tFileOutputXML component to define its properties.

  2. In the Basic settings tab, click the [...] button next to the File Name field then browse to the location on your file system where the output file will be stored, or enter the path manually between double quotes.

  3. Click the [...] button next to Edit schema to define the schema.

  4. Add three columns to the input schema on the left and rename them id, date and name, copy them to the output schema on the right, and then click OK.

  5. Leave the other elements unchanged.

Defining the properties of tHMap

  1. Select the tHMap component to define its properties.

  2. Click the [...] button next to the Open Map Editor field to create a new map based on the input and output of tHMap.

  3. In the tHMap Structure Generate/Select dialog box that opens, select Generate hierarchical mapper structure based on the schema and then click Next to generate the input structure.

  4. Do the same for the output structure.

  5. In the Map editor that opens, drag the txn_id element of Input (map) to the id element of Output (map). Do the same to map payment_date to date and first_name to name, and then save your changes.

Saving and executing the Job

  1. Press Ctrl+S to save your Job.

  2. In the Run tab, click Run to execute the Job.

  3. Browse to the location on your file system where the output file is stored to check that an XML file has been created containing the same data as the input CSV file.

Scenario 3: Transforming from a Data Integration schema to a complex content schema

The following scenario creates a three-component Job, generating some random data from an input component, transforming this data using a map which was previously created in the Mapping perspective, and then outputting the transformed data in a JSON file. It works with Talend Data Integration metadata for the input and Talend Data Mapper metadata for the output.

Creating a new structure in the Mapping perspective

  1. In the Mapping perspective, in the Data Mapper view, expand the Hierarchical Mapper node, right-click Structures and then select New > Structure.

  2. In the [New Structure] dialog box that opens, select Create a new structure where you manually enter elements, and then click Next.

  3. Name your structure JSON_structure, and then click Next.

  4. In the [Select Representation] dialog box, select JSON from the list of available representations, and then click Next.

  5. Select Don't select a sample document for now, and then click Finish.

Entering the elements for your new structure

  1. In the Mapping perspective, in the Data Mapper view, expand the Hierarchical Mapper node and the Structures node, and then open the JSON_structure structure you created earlier.

  2. In the JSON_structure, right-click to add a new element, click New element and name the new element Root.

  3. Follow the same steps to create a new element called people under the Root element, a person element under people, and four new elements under the person element: firstname, lastname, address and city.

  4. For the person element, change the Occurs Max value to -1 (unlimited).

  5. Press Ctrl + S to save your changes.

Adding and linking the components

  1. In the Integration perspective, in the Repository, right-click Job Designs, and then click Create Standard Job to create a Job named di_to_json. Add a Purpose and Description if you wish, and then click Finish.

  2. Click the point in the design workspace where you want to add the first component, start typing tRowGenerator, and then click the name of the component when it is displayed in the list proposed in order to select it.

  3. Do the same to add a tHMap component, and a tFileOutputRaw component as well.

  4. Connect the tRowGenerator component to the tHMap component using a Row > Main link, then connect the tHMap component to the tFileOutputRaw component using a Row > Main link. When you are asked if you want to get the schema of the target component, click Yes.

Defining the properties of tRowGenerator

  1. Select the tRowGenerator component to define its properties.

  2. In the Basic settings tab, click the [...] button next to RowGenerator Editor to define the rows to be generated.

  3. In the dialog box that opens, click four times the [+] button to add four new columns to the schema, and name them firstname, lastname, address and city.

  4. For each of the columns you just added, change the function to match what is shown in the table below by clicking in the Functions column and scrolling through the list of available functions until you find the one you want, and then click OK when you're done.

    firstname

    TalendDataGenerator.getFirstName

    lastname

    TalendDataGenerator.getFirstName

    address

    TalendDataGenerator.getUsStreet

    city

    TalendDataGenerator.getUsCity

Defining the properties of tFileOutputRaw

  1. Select the tFileOutputRaw component to define its properties.

  2. In the Basic settings tab, click the [...] button then browse to the location on your file system where the output file is to be stored, or enter the path manually between double quotes, and call the output file output.json

    Leave the other parameters unchanged.

Defining the properties of tHMap

  1. Select the tHMap component to define its properties.

  2. Click the [...] button next to the Open Map Editor field to create a new map.

  3. In the [tHMap Structure Generate/Select] dialog box that opens, select Generate hierarchical mapper structure based on the schema for the input structure, and then click Next and then Finish. This means that Talend Data Mapper will automatically generate a structure for you, based on the schema of the input component (tRowGenerator in this case).

  4. For the output structure, select Select an existing hierarchical mapper structure, and then click Next.

  5. Select the JSON_structure structure that you created earlier, and then click Next and then Finish.

  6. In the Map editor that opens, drag row from Input (Map) to person in Output (JSON) to map each of the input elements to its corresponding output element.

  7. Double click SimpleLoop in Loop tab and, in the properties box that opens, check Stream Input and then click OK.

  8. Press Ctrl+S to save your changes to the map.

Saving and executing the Job

  1. Press Ctrl+S to save your Job.

  2. In the Run tab, click Run to execute the Job.

  3. Browse to the location on your file system where the output file is stored to check that a JSON file showing the expected data has been successfully created.

Scenario 4: Handling errors

This following scenario creates a six-component Job that shows how to handle error conditions using the tHMap component.

When tHMap executes a Talend Data Mapper map, an ExecutionStatus object is always returned. A pointer to this object is stored in the globalMap as EXECUTION_STATUS. In addition, the Overall Severity numeric value (the constants are defined in ExecutionStatus) is also stored in the globalMap as EXECUTION_SEVERITY. Finally, a parameter called Execution Threshold is defined that specifies the severity on which to throw an exception, thus triggering Job-related or component-related error processing. The default value for this parameter is Fatal.

To consult the Javadoc for the ExecutionStatus object, see the Camel Runtime documentation included in the Talend Data Mapper runtime kits and the Talend Data Mapper User Guide.

Adding and linking the components

  1. In the Integration perspective, create a new Standard Job and call it error_handling.

  2. Click the point in the design workspace where you want to add the first component, start typing tFixedFlowInput, and then click the name of the component when it appears in the list proposed in order to select it.

  3. Do the same to add a tHMap component, a tJavaRow component, and three tJava components as well.

  4. Connect the tFixedFlowInput component to the tHMap component using a Row > Main link, then connect the tHMap component to the tJavaRow component using a Row > Main link and rename the link out. If you are asked whether you want to get the schema of the target component, click Yes.

  5. Connect the tFixedFlowInput component to the first tJava component using an OnSubjobError trigger and to the second tJava component using an OnSubjobOk trigger, then connect the tHMap component to the third tJava component using a RunIf trigger.

Defining the properties of the RunIf trigger

  1. Select the RunIf trigger to define its properties.

  2. Add the following code in the Condition section.

    !((org.talend.transform.runtime.api.ExecutionStatus) globalMap.get("tHMap_1_EXECUTION_STATUS")).isOK()

Defining the properties of tFixedFlowInput

  1. Select the tFixedFlowInput component to define its properties.

  2. In the Basic settings tab, click the [...] button next to Edit schema to define the schema.

  3. Add one column, of type String, rename it inputKey, and then click OK.

  4. In the Mode area. select the Use Inline Table radio button, then add three values to the inputKey column by clicking the [+]  button and then entering the value between double quotes in each case. In this example, the values used are value1, value2 and value3.

Defining the properties of tJavaRow

  1. Select the tJavaRow component to define its properties.

  2. In the Basic settings tab, click the [...] button next to Edit schema to define the schema.

  3. Click the [+]  button to add a column to the input schema on the left, of type String, rename it outputKey, copy it to the output schema on the right, and then click OK.

  4. Add the following code in the Code section.

    String actualOutput = out.outputKey;
    
    System.out.println("======" + actualOutput + "======");

Defining the properties of tHMap

  1. Select the tHMap component to define its properties.

  2. Click the [...] button next to the Open Map Editor field to create a new map based on the input and output of tHMap.

  3. In the tHMap Structure Generate/Select dialog box that opens, select Generate hierarchical mapper structure based on the schema and then click Next to generate the input structure.

  4. Do the same for the output structure.

  5. In the Map editor that opens, drag the inputKey element of Input (map) to the outputKey element of Output (map), and then save your changes.

  6. Back in the Job, in the tHMap component, leave the value of the Exception Threshold drop-down list (in the Advanced settings tab) as Fatal.

  7. In the Basic settings tab, check that Read Input As is set to Data Integration columns.

  8. Check that Write Output As is set to Data Integration columns.

Defining the properties of the first tJava component (OnSubjobError)

  1. Select the first tJava component to define its properties. This component displays information in the console when the Job contains an error.

  2. Add the following code in the Code section.

    System.out.println("tJava_1: Subjob ERROR");
    
    org.talend.transform.runtime.api.ExecutionStatus es = (org.talend.transform.runtime.api.ExecutionStatus)globalMap.get("tHMap_1_EXECUTION_STATUS");
    
    System.out.println("Execution result:" + es.getOverallSeverity());
    
    // ExecutionStatus object
    System.out.println(es.toString());
    
    // XML version of ExecutionStatus object
    java.io.StringWriter sw = new java.io.StringWriter();
    es.exportToXml(sw);
    System.out.println("ExecutionStatus as XML");
    System.out.println(sw.toString());

Defining the properties of the second tJava component (OnSubjobOk)

  1. Select the second tJava component to define its properties. This component displays information in the console when the Job runs successfully.

  2. Add the following code in the Code section.

    System.out.println("tJava_2: Subjob OK");
    
    org.talend.transform.runtime.api.ExecutionStatus es = (org.talend.transform.runtime.api.ExecutionStatus)globalMap.get("tHMap_1_EXECUTION_STATUS");
    
    System.out.println("Execution result:" + es.getOverallSeverity());
    
    // ExecutionStatus object
    System.out.println(es.toString());
    
    // XML version of ExecutionStatus object
    java.io.StringWriter sw = new java.io.StringWriter();
    es.exportToXml(sw);
    System.out.println("ExecutionStatus as XML");
    System.out.println(sw.toString());

Defining the properties of the third tJava component (RunIf)

  1. Select the third tJava component to define its properties. This component runs if any errors occur within the map itself (higher than informational status).

  2. Add the following code in the Code section.

    System.out.println("tJava_3: Run If");
    
    org.talend.transform.runtime.api.ExecutionStatus es = (org.talend.transform.runtime.api.ExecutionStatus)globalMap.get("tHMap_1_EXECUTION_STATUS");
    
    System.out.println("Execution result:" + es.getOverallSeverity());
    
    // ExecutionStatus object
    System.out.println(es.toString());
    
    // XML version of ExecutionStatus object
    java.io.StringWriter sw = new java.io.StringWriter();
    es.exportToXml(sw);
    System.out.println("ExecutionStatus as XML");
    System.out.println(sw.toString());

Running the Job under different conditions

  1. Press Ctrl+S to save your Job.

  2. In the Run tab, click Run to execute the Job.

    In this case, no errors occur, so the Job triggers the second tJava component only.

  3. Double-click the tHMap component to open the Map editor.

  4. Right-click the outputKey element and click Go to Structure Element.

  5. Change the tHMap_1_output structure that opens from Read Only to Editable and then change the Data Type for outputkey to Integer (32). This means that this element can only be an Integer, and since this does not match the input, an error will occur.

  6. In the Run tab, click Run to execute the Job again.

    In this case, the Job still triggers the second tJava component even though there is an error, because the threshold above which an exception should be thrown (thus enabling the downstream components to detect the error) is set as Fatal. However, the third tJava component is also triggered since there is an error in the execution of the map.

  7. In the tHMap component, change the value of the Exception Threshold drop-down list (on the Advanced Settings tab) to Error. This causes an exception to be thrown when the map has a severity of Error or higher.

  8. In the Run tab, click Run to execute the Job for a third time.

    In this case, the Job detects the error and triggers the first tJava component (OnSubjobError).