Model relationships and record changes

HDL files can represent complete business-object hierarchies as well as targeted changes to individual components. Correctly identify parent and related records so that HDL can assemble the supplied data into the intended logical objects and process changes without conflicting instructions.

Identify the parent of every child record

Child components are processed as part of their parent business-object hierarchy. Each child must therefore provide enough information to identify both the child record and the parent record to which it belongs.

A child component must:

• Identify itself uniquely and
• Identify its parent uniquely

For example, if JobGrade is a child of Job, the JobGrade line must identify which Job owns the valid-grade record.

You can use whichever parent-reference key type the component supports.

View Business Objects identifies:

• the Parent Surrogate ID attribute;
• supported integration keys;
• supported user-key combinations.

Reference related objects using supported foreign keys

A component can also reference another, independent business object.

For example, a Job Valid Grade needs to reference a Grade.

Where integration keys are supported, you can supply a source-system identifier through the foreign object's surrogate-ID attribute using an HDL hint.

For example:

Here:

• SCN_IC1 identifies the JobGrade record;
• SCN identifies the parent Job by its SourceSystemId;
• IC1 identifies the referenced Grade by its SourceSystemId.

If the referenced object uses a different SourceSystemOwner, also provide a (SourceSystemOwner) hint for that reference.

The referenced object must exist

An integration-key reference isn't usable until the referenced object has been created successfully.

If multiple related .dat files are supplied in the same ZIP, HDL loads business objects in dependency order. A reference will still fail if the referenced record itself failed to load.

Add or update child records without resupplying the whole object

You don't have to resupply an entire hierarchy to change one part of it.

For example, you can include the top-level component to identify the logical object and then supply only the child records that need to be created or changed.

This partial-object model is one of HDL's key strengths.

Avoid competing instructions for the same logical record

HDL groups related lines into logical objects; it doesn't simply process the file top-to-bottom as independent commands.

Don't rely on line order to resolve conflicting instructions.

In particular:

• don't use both MERGE and DELETE for the same logical record in one file;
• for a non-date-effective record, don't try to create and then separately update that same component in the same file as two processing stages.

You can, however, MERGE one component of a logical object while DELETEing another component where that combination is valid.