tSchemaComplianceCheck

Ensures the data quality of any source data against a reference data source.

tSchemaComplianceCheck validates all input rows against a
reference schema or check types, nullability, length of rows against reference values.
The validation can be carried out in full or partly.

Depending on the Talend solution you
are using, this component can be used in one, some or all of the following Job
frameworks:

Standard: see tSchemaComplianceCheck Standard properties.

The component in this framework is generally available.
MapReduce: see tSchemaComplianceCheck MapReduce properties.

The component in this framework is available only if you have subscribed to one
of the
Talend
solutions with Big Data.

tSchemaComplianceCheck Standard properties

These properties are used to configure tSchemaComplianceCheck running in the Standard Job framework.

The Standard
tSchemaComplianceCheck component belongs to the Data Quality family.

The component in this framework is generally available.

Basic settings

Base Schema and Edit schema	A schema is a row description. It defines the number of fields (columns) to be processed and passed on to the next component. The schema is either Built-In or stored remotely in the Repository. It describes the structure and nature of your data to be processed as it is.
	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.
Check all columns from schema	Select this option to carry out all checks on all columns against the base schema.
Custom defined	Select this option to carry out particular checks on particular columns. When this option is selected, the Checked Columns table shows.
Checked Columns	In this table, define what checks are to be carried out on which columns.
	Column: Displays the columns names.
	Type: Select the type of data each column is supposed to contain. This validation is mandatory for all columns.
	Date pattern: Define the expected date format for each column with the data type of Date.
	Nullable: Select the check box in an individual column to define the column to be nullable, that is, to allow empty rows in this column to go to the output flow regardless of the base schema definition. To define all columns to be nullable, select the check box in the table header.
	Undefined or empty: Select the check box in an individual column to reject empty rows in this column while the column is not nullable in the base schema definition. To carry out this verification on all the columns, select the check box in the table header.
	Max length: Select the check box in an individual column to verify the data length of the column against the length definition of the base schema. To carry out this verification on all the columns, select the check box in the table header.
Use another schema for compliance check	Define a reference schema as you expect the data to be, in order to reject the non-compliant data. It can be restrictive on data type, null values, and/or length.
Trim the excess content of column when length checking chosen and the length is greater than defined length	With any of the three modes of tSchemaComplianceCheck, select this check box to truncate the data that exceeds the length specified rather than reject it. Note: This option is applicable only on data of String type.

Advanced settings

Use Fastest Date Check	Select this check box to perform a fast date format check using the TalendDate.isDate() method of the TalendDate system routine if Date pattern is not defined. For more information about routines, see Talend Studio User Guide.
Ignore TimeZone when Check Date	Select this check box to ignore the time zone setup upon date check. Not available when the Check all columns from schema mode is selected.
Treat all empty string as NULL	Select this check box to treat any empty fields in any columns as null values, instead of empty strings. By default, this check box is selected. When it is cleared, the Choose Column(s) table shows to let you select individual columns.
tStatCatcher Statistics	Select this check box to collect log data at the component level.

Global
Variables

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. 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.

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.

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

Usage rule	This component is an intermediary step in the flow allowing to exclude from the main flow the non-compliant data. This component cannot be a start component as it requires an input flow. It also requires at least one output component to gather the validated flow, and possibly a second output component for rejected data using Rejects link. For more information, see Talend Studio User Guide.

Scenario: Validating data against schema

This scenario applies only to a subscription-based Talend Platform solution or Talend Data Fabric.

This scenario presents a Job that checks the type, nullability and length of data from
an incoming flow against a defined reference schema, and displays the validation results
on the Run console.

The incoming flow comes from a simple CSV file that contains heterogeneous data
including wrong data type, data exceeding the maximum length, wrong ID and null values
in non-nullable columns, as shown below:

ID;Name;BirthDate;State;City
1;Dwight;06-04-2008;Delaware;Concord
2;Warren;25-10-2008;Montana
3;Benjamin;17-08-2008;Washington;Austin
4;Harry;14-04-2008;Kansas;Annapolis
5;Ulysses;2007-04-12;Michigan;Raleigh
6;James;19-08-2007;Delaware;Charleston
.7;Bill;20-04-2007;Illinois;Bismarck
8;Ulysses;04-12-2008;;Saint Paul
9;Thomas;09-05-2008;Maryland;Albany
10;Ronald;11-02-2008;Florida;Hartford

ID;Name;BirthDate;State;City

1;Dwight;06-04-2008;Delaware;Concord

2;Warren;25-10-2008;Montana

3;Benjamin;17-08-2008;Washington;Austin

4;Harry;14-04-2008;Kansas;Annapolis

5;Ulysses;2007-04-12;Michigan;Raleigh

6;James;19-08-2007;Delaware;Charleston

.7;Bill;20-04-2007;Illinois;Bismarck

8;Ulysses;04-12-2008;;Saint Paul

9;Thomas;09-05-2008;Maryland;Albany

10;Ronald;11-02-2008;Florida;Hartford

Setting up the Job

Drop the following components: a tFileInputDelimited, a tSchemaComplianceCheck, and two tLogRow components from the Palette to the design workspace.
Connect the tFileInputDelimited component
to the tSchemaComplianceCheck component
using a Row > Main connection.
Connect the tSchemaComplianceCheck
component to the first tLogRow component
using a Row > Main connection. This
output flow will gather the valid data.
Connect the tSchemaComplianceCheck
component to the second tLogRow component
using a Row > Rejects connection. This
second output flow will gather the non-compliant data. It passes two
additional columns to the next component: ErrorCode and
ErrorMessage. These two read-only columns provide
information about the rejected data to ease error handling and
troubleshooting if needed.

Configuring the components

Double-click the tFileInputDelimited
component to display its Basic settings
view and define the basic parameters including the input file name and the
number of header rows to skip.
Click the […] button next to Edit schema to describe the data structure of the
input file. In this use case, the schema is made of five columns:
ID, Name,
BirthDate, State, and
City.
Fill the Length field for the
Name, State and
City columns with 7,
10 and 10 respectively. Then
click OK to close the schema dialog box and
propagate the schema.
Double-click the tSchemaComplianceCheck
component to display its Basic settings
view, wherein you will define most of the validation parameters.
Select the Custom defined option in the
Mode area to perform custom defined
checks.

In this example, we use the Checked
columns table to set the validation parameters. However, you
can also select the Check all columns from
schema check box if you want to perform all the checks (type,
nullability and length) on all the columns against the base schema, or
select the Use another schema for compliance
check option and define a new schema as the expected
structure of the data.
In the Checked Columns table, define the
checks to be performed. In this use case:

– The type of the ID column should be Int.

– The length of the Name, State
and City columns should be checked.

– The type of the BirthDate column should be
Date, and the expected date pattern is
dd-MM-yyyy.

– All the columns should be checked for null values, so clear the
Nullable check box for all the
columns.

Note:

To send rows containing fields exceeding the defined maximum length to
the reject flow, make sure that the Trim the
excess content of column when length checking chosen and the length
is greater than defined length check box is cleared.
In the Advanced settings view of the
tSchemaComplianceCheck component,
select the Treat all empty string as NULL
option to sent any rows containing empty fields to the reject flow.
To view the validation result in tables on the Run console, double-click each tLogRow component and select the Table option in the Basic
settings view.

Executing the Job

Save your Job and press F6 to launch it.

Two tables are displayed on the console, showing the valid data and
rejected data respectively.