NumberDropDownFields property

The number drop-down fields of the app as an array.

Accessing all number drop-down fields of the app through this property has many uses:

• Deciding which background color to use based on whether the number drop-down fields of the app are valid.
• Calculating the sum of all number drop-down fields of the app.
• Enabling a button only if all number drop-down fields of a form screen have been filled out.
• Collecting the labels and values of all number drop-down fields of a app as a text string, for use as the body of an email.

The following sections detail how these scenarios can be realized. Skip to the examples at the bottom for the concise version.

Making the background color red if a number drop-down field is invalid

The BackgroundColor property determines the background color of a screen and all screens that follow that have no explicit background color set. That means that if the background color is set for the first screen of an app, and no other screens have a background color set, the first screen determines the background color of the entire app.

We can make use of this knowledge to make the background of the entire app red, but only if at least one number drop-down field of the app is invalid. This formula is associated with the BackgroundColor property of the first screen:

The formula fragment App.NumberDropDownFields.ValidApp,NumberDropDownFields,Valid returns a logical array, where TRUE indicates that the corresponding number drop-down field is valid and FALSE indicates that the corresponding number drop-down field is invalid. Applying the NOT function to this array negates every element, meaning that TRUE indicates that a number drop-down field is invalid and FALSE indicates that a number drop-down field is valid. (The ! operator would have had the same effect.)

Then, the OR function is applied to this array. It returns FALSE only if all elements of the array are FALSE. In other words, it returns TRUE if one or several elements are TRUE, meaning that it returns TRUE if one or several number drop-down fields are invalid.

Finally, the IF function is used to return the color red if one or several number drop-down fields are invalid. Otherwise, IF returns a blank value, which has no effect on the background color. The net effect is that the background color of the app is made red if one or several number drop-down fields of the app are invalid.

Summing all number drop-down fields

This formula returns the sum of the values of all number drop-down fields of the app:

The formula above can also be written as follows:

However, as the SUM function is looking for an array of numbers to add together, and number drop-down fields return numbers through their Value properties, .Value,Value is inferred and does not need to be spelled out.

In fact, you may be able to make the formula even shorter:

In the formula above, .Items.Value,Items,Value is inferred. In other words, the Items property is accessed, which includes not only fields, but also buttons and text boxes. As buttons and text boxes cannot return numbers, they are ignored by the SUM function, meaning that SUM(App)SUM(App) returns the sum of all items that can return numbers, including number fields, number drop-down fields and date and time fields.

If you explicitly only want to include the values of number drop-down fields, and not values of number fields and date and time fields, be sure to write SUM(App.NumberDropDownFields)SUM(App,NumberDropDownFields).

Summing the other number drop-down fields of the app

Let's say that the app consists of ten number drop-down fields, Field1 through Field10. If Field10 should contain the sum of the other number drop-down fields, it is tempting to try to associate this formula with the Value property of Field10:

However, that formula will not work. Instead, you'll get an error message, because you're effectively asking that the calculated value of Field10 includes the value of Field10 itself.

This is similar to trying to use the formula Field1 * 2Field1 * 2 for the Value property of Field1, effectively asking that the value of Field1 should be set to the value of Field1, multiplied by two. This is known as a circular calculation, and results in an error message.

In order to solve this issue, the formula needs to reference the number drop-down fields to include in the calculation explicitly:

Above, Field1:Field9Field1:Field9 creates an array consisting of Field1, Field9 and all items that appear between them. Notably, Field10 is not part of the array.

Enabling a button only if all number drop-down fields have been filled out

The Enabled property of a button determines if users can interact with the button. If a button should only be enabled if all number drop-down fields of the app have been filled out, associate this formula with the Enabled property of the button:

The ISDEFINED function returns a logical array when its sole parameter is an array. TRUE elements in the array indicate that the fields have defined values, that is, have been filled out. Conversely, FALSE elements indicate that the fields have not been filled out.

Finally, the AND function returns TRUE only if all elements of the array are TRUE, otherwise it returns FALSE. The net effect is that AND returns TRUE only if all number drop-down fields of the app have been filled out, prompting the Enabled property to only allow users to press the button once all fields have defined values.

Including all number drop-down values field of the app in an email

The Body property of email report buttons allows the body of an email to be set through a formula. While email report buttons have built-in support for including field values, through the IncludedFields property, building a text string manually to include in the email body allows us more flexibility.

Consider this formula, which should be associated with the Body property of an email report button:

Above, the formula fragment App.NumberDropDownFields.LabelApp,NumberDropDownFields,Label returns a text array, made up of the labels of the number drop-down fields of the app. The formula fragment App.NumberDropDownFields.ValueApp,NumberDropDownFields,Value also returns an array, this time made up of the values of the number drop-down fields. Using &, the labels are joined together with the values, separated by a colon.

The resulting text array, where every element consists of a label, followed by a colon and a value, is converted into a single text string using the TEXTJOIN function. Its first parameter, NEWLINE()NEWLINE(), ensures that the array elements are separated from one another using line breaks.

Ranges versus this property

If the app only consists of the number drop-down fields Field1, Field2 and Field3, these formulas are equivalent:

The second formula uses a range to create an array consisting of Field1, Field3 and all items that appear between them, which in this case is only Field2.

The chief advantage of the NumberDropDownFields property, compared to a range, is that there is no need to update formulas when additional number drop-down fields are added to the app. If Field4 were to be added to the app, the Field1:Field3Field1:Field3 range would have to be changed to Field1:Field4Field1:Field4 everywhere it is used.

By contrast, App.NumberDropDownFieldsApp,NumberDropDownFields automatically includes Field4, and any other number drop-down fields that are added.

Filtering number drop-down fields

If you want to process only a subset of the number drop-down fields returned from this property, use the FILTER function. It can base its decision on which number drop-down fields to return on the property values of the number drop-down fields.

This formula only returns visible number drop-down fields:

Crucially, you can also filter on the names of the number drop-down fields, using standard text functions. This formula only returns number drop-down fields whose names include the text string "Required":

If you use a deliberate naming strategy for your number drop-down fields, you can use FILTER in conjunction with this property to ensure that you only process a specific subset of number drop-down fields.

Related properties

Use the NumberDropDownFields property of a form screen to access all number drop-down fields of said form screen and the NumberDropDownFields property of a form group to access all number drop-down fields of said form group.

The Fields property returns all fields of the app, not just number drop-down fields. The Items property returns all items of the app, including fields, buttons, text boxes and named values. Use NumberFields, TextFields, SwitchFields, DateTimeFields and TextDropDownFields to access other kinds of fields.

Examples