Linked fields
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Linked fields are fields containing information from a different database. Collections retrieves the linked data from a specified database and displays it in standard database fields. That means you can process this data on detailed display screens in the same way as data in standard fields. If you put the retrieved data in fields that can be modified by the user, Collections can write the modified data back to the linked file if you have specified so.
The database in which you want to search for data is referred to as the linked or secondary database. The current database, to which you want to link data, is referred to as the primary database.
So for a link you should create a tag in the primary database, which will contain the key data (e.g. a person’s name) that a user fills in. This is called the linked field (even though it is located in the primary database). Collections will use this key data to search the linked database for related or substitutional (preferred) data.
In the properties of a linked field, you specify:
| • | the index field in the linked database in which the key data is searched (e.g. the name index in the people database). This is called the lookup field (the field you link to). |
| • | for each item of data to be retrieved (aka merged in) from the linked record: the tag in the linked database containing the data, and the tag in the primary database to which the data is to be copied (e.g. street, town/city and postal code). |
| • | (optionally) for each item of data to be written back to the linked record: the tag in the linked file to which the data is to be written, and the tag in the primary file in which the data to be written to the linked file is entered by the user. |
You can also specify that a user is allowed to add new key data to a linked database via the linked field, by marking the Allow the creation of new linked records option for the linked field. This is also called "forcing records", in old Adlib terminology.
A linked field must be specified as multilingual if the field it links to is multilingual as well.
For Axiell Collections, all linked field must be linked on forward reference. This means that a separate field tag must exist to contain the record number of the linked record. This separate (integer) field must then be entered in Forward reference property of the linked field. The advantage of link field on reference is that the linked field value nor any merged-in values are stored in the primary record, only the record number of the linked record will be stored. That allows the user to edit the linked record from within the linked (secondary) database, after which the value displayed in the linked field in all primary databases will change accordingly automatically. So the linked field is filled only then with the key data from a record in the linked database, when it is required (for instance when the user opens, prints or exports a primary record with this linked field)
Forward reference fields should be defined as normal database fields, of the integer data type, and repeatable if its associated linked field is, and a member of the same field group (if any). A forward reference field must never be multilingual, even if it is associated with a multilingual linked field (because the record number stored in the link reference field doesn't have translations).
You should always make an index on the link reference field.
See also