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Data entity wizard rules

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This article provides information about the natural key expansion of surrogate foreign key fields and the expansion of child/parent relations.

Natural key expansion of surrogate foreign keys

A surrogate foreign key field's extended data type must be RefRecId or a derivative. The natural key expansion of a surrogate foreign key field uses the rules in the following list. These rules are listed in the order of evaluation.

  1. Replacement key – The replacement key fields
  2. Primary key – The primary index key fields
  3. Alternate key – The first unique alternate key
  4. Auto-identification key – The auto-identification fields

Surrogate foreign key fields that are nested in the natural key are recursively expanded. Recurring nested surrogates are limited to the first occurrence. If you select the is mapped property of a surrogate foreign key (that is, if you set the property to true), the related data source is automatically added to the entity, and the is mapped property of each field in the related data source's natural key is selected. In addition, any nested surrogate foreign key data sources are recursively added to the entity. If you clear the is mapped property of a surrogate foreign key (that is, if you set the property to false), the related data source are automatically removed and unmapped from the entity and any nested surrogate foreign key data sources. The effect of selecting and clearing the is mapped property of a surrogate foreign key field differs from the effect of using the Add data source and Remove data source buttons. If you add a surrogate foreign key data source, the is mapped property of the parent data source surrogate foreign key field isn't automatically set to true. If you are removing a surrogate foreign key data source, the is mapped property of the parent data source surrogate foreign key field isn't automatically set to false. By default, the is mapped property of the root data source's surrogate foreign key field is set to true. Therefore, by default, surrogate foreign key relations are expanded to one level.

Expansion of parent/child relations

Parent/child relations are composition/extension relations that are stored as a relation on the child table. The parent table doesn't detect the relation. A parent/child relation can be either a surrogate foreign key relation or a natural foreign key. Parent/child relations use the following rules:

  • The collection of child tables is obtained by querying the cross-reference database for "type reference" relations to the parent table.
  • The child table must belong to the same table group as the parent table.
  • The relation between the child and parent relationship type property must be association, composition, link, or aggregation.
  • The relation between the child and parent cardinality property must be exactly one or zero or one.
  • The relation between the child and parent related table cardinality property must be exactly one or zero or one.

By default, parent/child relations aren't expanded. You must add them by using the Add data source button. To change the default behavior for a project in Microsoft Visual Studio, set the Expand parent/child option to true.

Using label text as field names

The following rules enable label text to be used as the field name when the option is selected (true):

  • All whitespace is removed from the label text.
  • The label text is truncated to 77 characters, and then a unique three-digit numeric identifier (000 through 999) is added.
  • The label text is passed to the NamedElement.IsValid method. If the name is valid, it can be used as the field name. Otherwise, the label text isn't used, and the field name remains unchanged.

The Is mandatory field

The default value of data entity fields is auto. This value is used unless it's explicitly changed. For relations, the related field's Is mandatory property is set based on the value of the field's Is mandatory value.

  • If the field's Is mandatory property and the related field's Is mandatory are both true, both fields are explicitly set to true.
  • If the field's Is mandatory property and the related field's Is mandatory are both false, both fields are explicitly set to false.

If the field's Is mandatory property and the related field's Is mandatory property differ in value, both fields remain unchanged. In this case, the default value of auto is used.