Operations with field values from sub-tasks

Configuration

Create a Custom smart number field and use the Jira expression parsing mode.

Expression

issue.subtasks.length && issue.subtasks.map( s => (s.customfield_nnnnn || 0) * 
(s.customfield_ppppp || 0)).reduce((a, b) => a + b)

Display as

Number

Formatting style

Default (unformatted)

Details

1. What does the expression do?

This expression calculates the sum of the products of two specific number fields for every sub-task of the current work item. In other words, for each sub-task, it multiplies the values of two chosen number fields together, then adds up all those results to give a single total.

2. Step-by-step breakdown

Here’s the expression:

issue.subtasks.length && issue.subtasks.map(s => (s.customfield_nnnnn || 0) * (s.customfield_ppppp || 0)).reduce((a, b) => a + b)

Let’s break it down:

• issue.subtasks.length && ...

  • Checks if there are any sub-tasks. If there are none, the result is 0.

• issue.subtasks.map(s => ...)

  • Goes through each sub-task (s) of the current work item.

• (s.customfield_nnnnn || 0)

  • Gets the value of the first Number field (replace nnnnn with the actual field ID). If the field is empty or missing, it uses 0.

• (s.customfield_ppppp || 0)

  • Gets the value of the second number field (replace ppppp with the actual field ID). If the field is empty or missing, it uses 0.

• (s.customfield_nnnnn || 0) * (s.customfield_ppppp || 0)

  • Multiplies the two field values for each sub-task.

• .reduce((a, b) => a + b)

  • Adds up (sums) all the multiplication results from each sub-task.

3. Examples

Suppose you have three sub-tasks, and you want to multiply the values of "Estimated Hours" (customfield_10001) and "Hourly Rate" (customfield_10002) for each sub-task, then sum the results:

• Sub-task 1: Estimated Hours = 2, Hourly Rate = 50 → 2 * 50 = 100

• Sub-task 2: Estimated Hours = 3, Hourly Rate = 60 → 3 * 60 = 180

• Sub-task 3: Estimated Hours = 1, Hourly Rate = 40 → 1 * 40 = 40

Total = 100 + 180 + 40 = 320

4. Real-life use cases

• Calculating total cost: If each sub-task has a "quantity" and a "unit price" field, this expression gives you the total cost across all sub-tasks.

• Summing weighted values: If you track "effort" and "priority" as numbers, you can get a weighted effort score for all sub-tasks.

• Project management: Quickly aggregate metrics like total estimated work, cost, or other calculated values from sub-tasks for reporting or dashboards.