A data group's schema defines all of the fields (including data items) that are available in the data group's data, regardless of whether the Fields option has been used to limit the output fields.

The schema is a fundamental part of the data gathering and designing processes in fSeries. It is kept up to date in the fData designer by the system detecting whenever a change is made that might affect the schema. For example, changing a Sql query, or adding a data item. If detected, the schema is refreshed to pick up the new schema. You can also manually refresh the schema from the “Refresh DSD Design” option on the fData Designer home page.

All fields and data items are shown in the list on the left. There is no significance to the sequence, but data items are shown first.

Data items are shown with the f(x) symbol. Fields are shown with the |x| symbol. Fields that are overwritten by a data item show both symbols.

Hold your mouse over a field for its details to be shown to the right.

Click on a field (not a data item) and the edit form shown above will open to the right. This lets you give the field a different name (used as a label or heading).

If the natural type of a field is not how you wish to use it, select its correct type in the Type As list. For example, dates are sometimes held in a data source as text (e.g. 2021-12-09), in which case you can change the Type As to dateTime and fData will treat the data as a date.

If the field's natural or effective type is number or dateTime, you can specify an Output Format in order to determine how the field will be displayed. In this case, the subject's STUD_ID is a number but instead of the automatic formatting inserting comma separators, the format (#) specifies that it should be displayed without commas. The Output Format Helper will be display for assistance.

If the data group type permits editing of schema fields (e.g. ApiJson and JsonSection) options will be provided to “Add Field” and “Discover Fields”.

Click “Add Field” to open a form where you can add a field directly into the schema. This is quicker and easier than adding a data item.

Give the new field a unique id, select the type and optionally enter a name.

Click this option to execute the latest saved version of this DSD to return the current data group only. fData will determine fields from the returned data and attempt to establish their type and name (these may be changed later). Only fields not yet present in the schema will be returned.

Check the box for each field you wish to add to the schema (or click Select All). The fields will be added to the schema.

Not that you may be asked to enter selection criteria for the DSD. Make entries that will return a full set of data in order to establish as many fields as possible. Similarly, try to make sure the returned data is populated with values as this makes it possible to establish accurate field types.