Change the Source Data Object
A Read transformation is based on a physical data object or a logical data object in the Model repository. You can change the data object when you configure a Read transformation. You can parameterize the data object to change the data object at run time. For example, you might test a mapping with a different source file than the source file you use for a production mapping run.
When you create a transformation from a physical data object, information about the data object appears on the Data Object tab of the transformation properties. You can click the data object name to view the physical data object definition from the Model repository.
You can change the data object for the transformation by browsing for a different physical data object in the Model repository. When you change the data object, the transformation uses the run time properties and the advanced properties of the data object that you select.
You can update the structure of the data object at run time based on changes in the data source. The data source is the physical file or the database table that the data object represents. When you enable the Data Integration Service to get data columns from the data source, the Data Integration Service examines the structure of the data source. The Data Integration Service updates the data object ports in the transformation instance based on the data source. The Data Integration Service does not change the physical data object definition in the Model repository.
The following image shows the Data Object tab:
The Data Object tab has the following fields:
- Specify by
- Choose Value to enter a specific data object name. Choose Parameter to parameterize the data object.
- Data object
- The name of the data object in the Model repository. You can click the Data Object link to open the data object definition from the repository. You can also Browse for a different data object in the Model repository.
- Description
- The description of the data object in the repository. Read-only.
- Data object type
- Describes the type of data object, such as a flat file data object, a relational table object, or a customized data object.
- At run time, get data object columns from the data source
- The Data Integration Service fetches metadata and data definition changes from the data file or the table that the data object refers to and updates the structure of the data object for the transformation instance at run time.
- To preview how the Data Integration Service fetches metadata and data definition changes at run time, view the mapping with resolved parameters.
Parameterize the Read Transformation
You can parameterize the Read transformation and change the data object at run time.
To parameterize a data object, choose Specify by Parameter in the Data Object tab. The properties in the Data Object tab change.
To parameterize the data object, create a resource type parameter or browse for a resource parameter that you already created. The parameter default value is the name of physical data object in the Model repository. When you create a default parameter value, you select a physical data object name from a list of data objects in the repository.
The following image shows the Data Object tab when you specify the data object by a parameter:
The Data Object tab has the following options by parameter:
- Parameter
- The name of a resource parameter that you configured as the data object. Read-only.
- Description
- The description of the parameter. Read-only.
- New
- Create a resource parameter. Browse for and select a data object in the Model repository for the parameter default value.
- Browse
- Browse for a resource parameter and select the parameter.
- Default value
- The default value of the resource parameter that you configured for the data object. The default value is a physical data object name and the path to the object in the Model repository. Read-only.
