Assume that we have a project with the following data.
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Date Arithmetic
Let us assume that one of the projects where you are a PM has completed. Now, you want to compare which of your resources, took more days to complete the task which impacted the project's deadline. their task.
For this, you need the Finish(Actual) date of (entity.actualFinishCalendar) of the task and the Deadline planned finish date of the project. Then, subtract these values to get the resultstask (entity.finishCalendar).
Since, these two fields are datesof type date, you cannot perform direct a direct operation on them. You need to first convert them to a number and then perform the operations. Create a formula field attached to task and get the field reference for the two fields i.e Finish (Actual) (entity.actualFinishCalendar) date of the task and Project's deadline (entity.project.deadlineCalendar). The formula operation. So, the formula will look like:
${(entity.project.deadlineCalendarfinishCalendar.time.time - entity.actualFinishCalendar.time.time)/86400000}
When you write ".time.time" it means that the date field is first converted to milliseconds for both the fields, then the subtraction is done. The result is again in milliseconds which needs to be converted again in days and hence, it is divided by 86400000. The result is the extra or less days taken by the resources to complete the task. The PM can pick this custom field as a column in a task report to see the difference.