## Formula fields

Formula fields are calculated from DBFields, other formulas, summaries, and parameters, so they can present information that DBFields cannot do.

### Inserting a formula field in a report

A formula field can be inserted in the report areas listed in Component placement. Before you can insert a formula field into a report, you need to define it. For details about how to define formulas, see Creating a formula.

To insert a formula field into a report, you can use either of the following two ways:

- Using dialog
  1. Position the mouse pointer at the destination where you want to insert the formula and do one of the following:
     - Click Insert > Formula on the menu bar.
     - Click the Insert Formula button on the Insert toolbar.

     The Insert Fields dialog appears. See the dialog.

  2. Select the required formula from the Formulas node, then specify its layout in the Insert Layout box.
  3. Click the Insert button to insert the formula into the destination.
- By dragging and dropping

  Select the required formula from the Formulas node of the Resource View panel, then drag it to the destination.

When a formula field has been inserted into a report, you can customize its appearance and behavior by setting properties in the Report Inspector, which can be saved as a CSS style for future use (for details, see Creating a CSS style).

Notes:

- No matter which way you take, if the given formulas are not what your want, you can click the <Add Formula...> item to create one as required.
- If you insert a formula into the detail panel of a component, the name of the formula will automatically be inserted as a label into the corresponding header panel. Otherwise the formula and its name label will be placed in the same panel. If you do not want to insert the name label automatically, you can go to the Options dialog, select Component in the Category box and then uncheck the Insert field name with field option.

### Changing the display type of a formula field

The display type of a formula field can be changed according to your requirements, that is to say, you can map the formula field to another value or image to be displayed instead.

To change the display type a formula field:

1. Right-click the formula field and select Display Type from the shortcut menu.
2. In the Display Type dialog, specify the required display type in the Type box, and set the options for the selected type in the Option panel.
3. Upon finishing, click the OK button to close the dialog.

For details about display types, see Changing the display type of a label.

### Binding a link to a formula field

You can make a formula field linked with another report, a URL or an e-mail. To do this:

1. Right-click the formula field and select Detail Report on the shortcut menu to display the Master/Detail Report dialog.
2. From the Link to drop-down list, specify the target to which the formula field will be linked.
3. Set the options for the target according to your requirements.
4. When done, click OK.

For details about different link targets, see Binding a link to a label.

### Adding conditional formats to a formula field

You can add some conditional formats to a formula field, then when the specified condition is fulfilled, the defined format will be applied to the field values for distinguishing.

To add conditional formats to a formula field:

1. Right-click the formula field and select Conditional Formatting from the shortcut menu.
2. In the Conditional Formatting dialog, click the button to add a condition as required.
3. Set the format that will be applied to the field values when the specified condition is fulfilled.
4. Repeat the above two steps to add more conditions and define the format for each condition as required.
5. When done, click OK to save the settings.

For more details about conditional formatting, see Adding conditional formats to a DBField.

See an example: The SampleComponents catalog, included with JReport Designer, contains reports that have examples of how each component type could be used in a report. For the formula field example, open `<install_root>\Demo\Reports\SampleComponents\UsingFormula.cls`.