Calculation field produce "undefined" result

Platform: 2.0.6:

I am designing drug order form in xform 4.3.11, I want to make length of Anti-TB prescription to be calculated from TB prescription end date and TB prescription start date, I followed, but calculated field gives undefined result. If needed I will try to reproduce


While in the form designer, can you select “Save As” from the “File” menu? Then paste the contents of the saved file at

Could you point me to the field to look at?


Do you have a screenshot?

Try change the calculation to: (new Date(/form/obs/tb_presc_end_date/value) - new Date(/form/obs/tb_presc_start_date/value))/ (1000 * 3600 * 24)

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Thank you so much @dkayiwa, live longer your majesty.

I want to do the same for ART and other drugs in the same form but it looks like you can only calculate one field and not more than that, when I tried to calculate more fields it says too much recursion. Is there a way to do the same for more than one field in one form?.

Can i see what you have done to result into that error?

I wanted to add calculation fields to other drugs, such as art, ipt, cotrimoxazole and others e.g (new Date(/form/obs/art_presc_end_date/value) - new Date(/form/obs/art_presc_start_date/value))/ (1000 * 3600 * 24) for art, (new Date(/form/obs/cot_presc_end_date/value) - new Date(/form/obs/cot_presc_start_date/value))/ (1000 * 3600 * 24) for cotrimoxazole, (new Date(/form/obs/ipt_presc_end_date/value) - new Date(/form/obs/ipt_presc_start_date/value))/ (1000 * 3600 * 24) for ipt, as shown in the screenshot

but when I preview the form it brings this error

Can you select “Save As” from the “File” menu and paste the file contents at

Looks like this form has some problems because I developed new form and works fine,

Good that you figured it out. :smile: