tExtractXMLField

tExtractXMLField properties

Component family	XML
Function	tExtractXMLField reads an input XML field of a file or a database table and extracts desired data.
Purpose	tExtractXMLField opens an input XML field, reads the XML structured data directly without having first to write it out to a temporary file, and finally sends data as defined in the schema to the following component via a Row link.
Basic settings	Property type	Either Built-in or Repository. Click Edit schema to make changes to the schema. If the current schema is of the Repository type, three options are available: View schema: choose this option to view the schema only. Change to built-in property: choose this option to change the schema to Built-in for local changes. Update repository connection: choose this option to change the schema stored in the repository and decide whether to propagate the changes to all the Jobs upon completion. If you just want to propagate the changes to the current Job, you can select No upon completion and choose this schema metadata again in the [Repository Content] window.
		Built-in: No property data is stored centrally.
		Repository: Properties are stored in a repository file. When this file is selected, the fields that follow are pre-filled in using fetched data.
	Schema type and Edit Schema	A schema is a row description. It defines the number of fields to be processed and passed on to the next component. The schema is either Built-In or stored remotely in the Repository.
		Built-In: You create and store the schema locally for this component only. Related topic: see Talend Studio User Guide.
		Repository: You have already created the schema and stored it in the Repository. You can reuse it in various projects and Job designs. Related topic: see Talend Studio User Guide.
	XML field	Name of the XML field to be processed. Related topic: see Talend Studio User Guide.
	Loop XPath query	Node of the XML tree, which the loop is based on.
	Mapping	Column: reflects the schema as defined by the Schema type field. XPath Query: Enter the fields to be extracted from the structured input. Get nodes: Select this check box to recuperate the XML content of all current nodes specified in the Xpath query list or select the check box next to specific XML nodes to recuperate only the content of the selected nodes.
	Limit	Maximum number of rows to be processed. If Limit is 0, no rows are read or processed. Note that this field is not available to the Map/Reduce version of tExtractXMLField.
	Die on error	Select this check box to stop the execution of the Job when an error occurs. Clear the check box to skip any rows on error and complete the process for error-free rows. When errors are skipped, you can collect the rows on error using a Row > Reject link.
Advanced settings	Ignore the namespaces	Select this check box to ignore namespaces when reading and extracting the XML data.
	tStatCatcher Statistics	Select this check box to gather the Job processing metadata at a Job level as well as at each component level. Note that this field is not available to the Map/Reduce version of tExtractXMLField.
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. NB_LINE: the number of rows processed. 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	This component is an intermediate component. It needs an input and an output components.
Usage in Map/Reduce Jobs	If you have subscribed to one of the Talend solutions with Big Data, you can also use this component as a Map/Reduce component. In a Talend Map/Reduce Job, this component is used as an intermediate step and other components used along with it must be Map/Reduce components, too. They generate native Map/Reduce code that can be executed directly in Hadoop. For further information about a Talend Map/Reduce Job, see the sections describing how to create, convert and configure a Talend Map/Reduce Job of the Talend Big Data Getting Started Guide. Note that in this documentation, unless otherwise explicitly stated, a scenario presents only Standard Jobs, that is to say traditional Talend data integration Jobs, and non Map/Reduce Jobs.
Log4j	The activity of this component can be logged using the log4j feature. For more information on this feature, see Talend Studio User Guide. For more information on the log4j logging levels, see the Apache documentation at http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/Level.html.
Limitation	n/a

Scenario 1: Extracting XML data from a field in a database table

This three-component scenario allows to read the XML structure included in the fields
of a database table and then extracts the data.

Drop the following components from the Palette onto the design workspace: tMysqlInput, tExtractXMLField,
and tFileOutputDelimited.

Connect the three components using Main
links.
Double-click tMysqlInput to display its
Basic settings view and define its
properties.
If you have already stored the input schema in the Repository tree view, select Repository first from the Property
Type list and then from the Schema list to display the [Repository
Content] dialog box where you can select the relevant metadata.

For more information about storing schema metadata in the Repository tree view, see Talend Studio User
Guide.

If you have not stored the input schema locally, select Built-in in the Property Type
and Schema fields and enter the database
connection and the data structure information manually. For more information
about tMysqlInput properties, see tMysqlInput.
In the Table Name field, enter the name of
the table holding the XML data, customerdetails in this
example.

Click Guess Query to display the query
corresponding to your schema.
Double-click tExtractXMLField to display its
Basic settings view and define its
properties.
Click Sync columns to retrieve the schema
from the preceding component. You can click the three-dot button next to
Edit schema to view/modify the
schema.

The Column field in the Mapping table will be automatically populated with the defined
schema.
In the Xml field list, select the column from
which you want to extract the XML data. In this example, the filed holding the
XML data is called CustomerDetails.

In the Loop XPath query field, enter the node
of the XML tree on which to loop to retrieve data.

In the Xpath query column, enter between
inverted commas the node of the XML field holding the data you want to extract,
CustomerName in this example.
Double-click tFileOutputDelimited to display
its Basic settings view and define its
properties.
In the File Name field, define or browse to
the path of the output file you want to write the extracted data in.

Click Sync columns to retrieve the schema
from the preceding component. If needed, click the three-dot button next to
Edit schema to view the schema.
Save your Job and click F6 to execute
it.

tExtractXMLField read and extracted the clients names
under the node CustomerName of the CustomerDetails
field of the defined database table.

Scenario 2: Extracting correct and erroneous data from an XML field in a delimited
file

This scenario describes a four-component Job that reads an XML structure from a
delimited file, outputs the main data and rejects the erroneous data.

Drop the following components from the Palette to the design workspace: tFileInputDelimited, tExtractXMLField, tFileOutputDelimited and tLogRow.

Connect the first three components using Row
Main links.

Connect tExtractXMLField to tLogRow using a Row
Reject link.
Double-click tFileInputDelimited to open its
Basic settings view and define the
component properties.
Select Built-in in the Schema list and fill in the file metadata manually in the
corresponding fields.

Click the three-dot button next to Edit
schema to display a dialog box where you can define the structure
of your data.

Click the plus button to add as many columns as needed to your data structure.
In this example, we have one column in the schema:
xmlStr.

Click OK to validate your changes and close
the dialog box.

Note

If you have already stored the schema in the Metadata folder under File
delimited, select Repository
from the Schema list and click the
three-dot button next to the field to display the [Repository Content] dialog box where you can select the
relevant schema from the list. Click Ok to
close the dialog box and have the fields automatically filled in with the
schema metadata.

For more information about storing schema metadata in the Repository tree
view, see Talend Studio User Guide.
In the File Name field, click the three-dot
button and browse to the input delimited file you want to process,
CustomerDetails_Error in this example.

This delimited file holds a number of simple XML lines separated by double
carriage return.

Set the row and field separators used in the input file in the corresponding
fields, double carriage return for the first and nothing for the second in this
example.

If needed, set Header, Footer and Limit. None is used
in this example.
In the design workspace, double-click tExtractXMLField to display its Basic
settings view and define the component properties.
Click Sync columns to retrieve the schema
from the preceding component. You can click the three-dot button next to
Edit schema to view/modify the
schema.

The Column field in the Mapping table will be automatically populated with the defined
schema.
In the Xml field list, select the column from
which you want to extract the XML data. In this example, the filed holding the
XML data is called xmlStr.

In the Loop XPath query field, enter the node
of the XML tree on which to loop to retrieve data.
In the design workspace, double-click tFileOutputDelimited to open its Basic
settings view and display the component properties.
In the File Name field, define or browse to
the output file you want to write the correct data in,
CustomerNames_right.csv in this example.

Click Sync columns to retrieve the schema of
the preceding component. You can click the three-dot button next to Edit schema to view/modify the schema.
In the design workspace, double-click tLogRow
to display its Basic settings view and define
the component properties.

Click Sync Columns to retrieve the schema of
the preceding component. For more information on this component, see tLogRow.
Save your Job and press F6 to execute it.

tExtractXMLField reads and extracts in the output
delimited file, CustomerNames_right, the client information for
which the XML structure is correct, and displays as well erroneous data on the console
of the Run view.

Document get from Talend https://help.talend.com

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Docs 5.x

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tExtractXMLField – Docs for ESB 5.x