Recomputing Link Expressions (Magic xpa 4.x)
Magic xpa will recompute the Link expression and reestablish the link when:
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A variable is part of the Locate From and To expressions.
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The variable used in the Locate From and To expressions is declared above the Link operation in the Data View Editor.
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The variable data has changed.
Refer to the description of Automatic Non-Procedural Recomputing of Init Expressions in the Data View variables.
A modifying variable is a component variable of the link expression, declared in the Data View Editor prior to the Link definition, and whose modification causes the recomputation of the link. The modifying variable can be changed because of user input, an Update operation, data import by a Form Input operation, another link's return code re-evaluation, or as a result of having been passed as an argument and changed in the called task.
Link recomputation can occur in Create or Modify modes. The change which triggers the recomputation can occur anywhere within the record cycle.
Warning: Be careful when you use the Update operation in the Record Suffix section on a variable that is a component of a Locate lower/upper expression of a link. The execution of the Update operation may cause the Link expression to be re-evaluated and the link to be re-established, thus causing the loss of the updated values of other variables selected from the Linked record.
When a link has failed, all Init expressions defined in the variables specified for that link are still evaluated and assigned to related variables following the same rules as variables that are not within a link.
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The Create type of link always fails, by definition.
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