Derived fields

In Dabble, derived fields are fields which do not contain stored data but instead show data “derived” from some other source. Derived fields aren’t stored, but are calculated on-the-fly as they are shown to you, so they automatically reflect changes in your data.

Derived fields show data connected to a linked entry or to a List of entries. You can add the derived field as a column on a table view, and the column will also be included on an associated Compact view or Calendar view as well as in Exports.

Other types of Field values may offer derived fields, such as the percent (multiply by 100) of Number values, or the geographical area of Location values. You can also derive units of time such as the month or year of a particular date.

1. Switch to a Table view.
2. Click the header of the column containing a Link to entry or List of entries field.
3. Move your mouse over Add derived field to reveal the submenu.
4. Click one of the menu items to add it as a column to the view. If you hold down the Shift key while you click, the new column will replace the existing column. Otherwise, it will be added to the immediate right.

What types of derived fields are available will depend on what type of field is in the original column, and also what data is stored in the value.

In all cases, you can show a field from a linked entry or listed entries. This allows you to show indirectly-related data without duplicating the actual data. (See the example below.)

For a List of entries, there are other derived fields you can add:

• You can derive a COUNT showing how many entries are listed instead of (or in addition to) just the names of those entries.

• You can derive which entry has the MAX or MIN value for a certain numeric field.

• You can find out the SUM or AVG of values in an existing derived field if it shows numeric data from several listed entries.
  • This is a two-step process: first you need to add the derived field containing numeric data. Then from the new column, you can add a derived field to show the sum or average of those values on each row (for each entry in the view with the list of entries field). Note that this is a different operation than the normal subtotals, which calculates the sum or average at the bottom of a column.

Derived fields showing numeric data act just like any field with Number values. You can show subtotals for the column. If the derived field contains a single numeric value, you can use it to create Formulas and for writing numeric Value filters.

Let’s say you have an application with information about people including their family relationships. Each person has a Link to entry field showing who the person’s mother is. You want to know what someone’s mother’s maiden name is, but that data is stored in the entry for the mothers themselves, not in the entries of their children. You can use a derived field to show the data in the right context.

In a view showing people entries, you would first add a column showing the link to each person’s mother (a link to entry field). Using a derived field, you would then add a column to the view showing what each person’s mother’s maiden name is. (Click on the “Mother” column, choose Add derived field, and select the “Maiden name” field.)