Configuring a Relational Direct Map Mapping (ELUG)

Related Topics

For information on how to create EclipseLink mappings, see Creating a Mapping.

This table lists the configurable options for a relational direct map mapping.

Option	Workbench	Java
Configuring Target Table
Direct value field
Direct key field
Method or direct field access
Read-only mapping
Batch reading
Indirection (lazy loading)
Container policy
Mapping comments
Key converters
Value converters
Table and field references

This example shows how to create a direct map mapping and add it to a descriptor using Java code.

Direct Map Mapping

public void customize(ClassDescriptor descriptor) { 
   DirectMapMapping mapping = new DirectMapMapping();  

   // configure mapping
   ... 

   // add mapping to descriptor
   descriptor.addMapping(mapping);
}

For more information, see the following:

• Direct Map Mapping
• Configuring a Relational Mapping
• Configuring a Mapping.

For information on using JPA to configure direct map mappings, see How to Use the @BasicMap Annotation.

Configuring Direct Value Field

The direct value field in the reference table stores the primitive data value of the map value. If the value's object value and database value are different types, use a converter (see Configuring Value Converters).

How to Configure Direct Value Fields Using Workbench

1. Select the mapped attribute in the Navigator. Its properties appear in the Editor.
2. Click the General tab. The General tab appears.
   General Tab, Direct Value Field
   
3. Use the Direct Value Field list to select the field from the Target Table table that contains the object of the direct map mapping.

How to Configure Direct Value Fields Using Java

Use the DirectMapMapping method setDirectFieldName to set the direct fields for your mapping.

For more information about the available methods for DirectMapMapping, see the EclipseLink API Reference.

Configuring Direct Key Field

The direct key field in the reference table stores the primitive data value of the map key. If the key's object value and database value are different types, use a converter (see Configuring Key Converters).

How to Configure Direct Key Field Using Workbench

To specify the direct key field in the reference table, use this procedure.

1. Select the mapped attribute in the Navigator. Its properties appear in the Editor.
2. Click the General tab. The General tab appears.
   General Tab, Direct Key Field
   
3. Use the Direct Key Field list to select the key from the Target Table table that contains the object of the direct map mapping.

How to Configure Direct Key Field Using Java

Use the DirectMapMapping method setDirectKeyFieldName to set the direct key field for your mapping.

For more information about the available methods for DirectMapMapping, see the EclipseLink API Reference.

Configuring Key Converters

If the key's object value and database value are different types, use a converter. EclipseLink supports the following key converters:

• Serialized Object Converter
• Type Conversion Converter
• Object Type Converter

How to Configure Key Converters Using Workbench

Use this procedure to specify the converter for a direct map mapping key:

1. Select the mapped attribute in the Navigator. Its properties appear in the Editor.
2. Click the Converter tab. The Converter tab appears.
3. Click the Key Converter tab. The Key Converter tab appears.
   Converter Tab, Key Converter Subtab
   
4. Select the appropriate Key Converter.

Converter	Description
No Converter	Do not use a Key Converter for this mapping.
Serialized Object Converter	See Configuring a Serialized Object Converter.
Type Conversion Converter	See Configuring a Type Conversion Converter.
Object Type Converter	See Configuring an Object Type Converter.

How to Configure Key Converters Using Java

You can configure whether or not to allow null values using the DirectMapMapping method setKeyConverter.

For more information about the available methods for DirectMapMapping, see the EclipseLink API Reference.

Configuring Value Converters

If the value's object value and database value are different types, use a converter. EclipseLink supports the following value converters:

• Serialized Object Converter
• Type Conversion Converter
• Object Type Converter

How to Configure Value Converters Using Workbench

1. Select the mapped attribute in the Navigator. Its properties appear in the Editor.
2. Click the Converter tab. The Converter tab appears.
3. Click the Value Converter tab. The Value Converter tab appears.
   Converter Tab, Value Converter Subtab
   
4. Select the appropriate Value Converter.

Converter	Description
No Converter	Do not use a Value Converter for this mapping.
Serialized Object Converter	See Configuring a Serialized Object Converter
Type Conversion Converter	See Configuring a Type Conversion Converter
Object Type Converter	See Configuring an Object Type Converter

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