Custom Functions

• Custom Functions
• endRange
  • Purpose
  • Why Use This Function?
  • Example Use Case
  • Backend Query Example
• dateTimeOf Custom Function
  • Returns
  • Behavior
  • Example of using the dateTimeOf custom function
• shortDateTimeOf(DateTime date)
• double depth(int n)
• generateEmptyList(int length)
• List<String> keys(dynamic json)

endRange

Purpose

Returns the end string of the search range.

Why Use This Function?

This function is designed for querying a string field within a specific range.

Example Use Case

Suppose you want to search for names that begin with "You". You can query like this:

name >= "You" && name < "You\uf8ff"

Backend Query Example

Below is an example of a backend query in a ListView to perform a case-insensitive user search.

dateTimeOf Custom Function

The dateTimeOf custom function converts a number into a DateTime object. The parameter should be a timestamp in seconds or milliseconds.

Returns

A DateTime object from a timestamp.

Behavior

• Seconds to Milliseconds: If the timestamp is in seconds, it will be converted to milliseconds and returns into the DateTime of it.
• Null Timestamp: If the timestamp is null, it will return the current time.
• Non-Integer Timestamp: If the timestamp is not an integer, it will throw an exception.
• Negative Timestamp: If the timestamp is negative, it will throw an exception.
• Zero Timestamp: If the timestamp is zero, it will return the current time.

Example of using the dateTimeOf custom function

See below to understand better on how to using it.

shortDateTimeOf(DateTime date)

double depth(int n)

• Returns

generateEmptyList(int length)

Returns a list of element.

• Use this to generate a list of element to use it in a Generate dynamic children panel.

List<String> keys(dynamic json)

Returns the keys of the JSON object.

• json can be null, or JSON type data.