How do I use the previous value in codes and combine manual input and code?

Do not confuse with the value of the previous line!

The previous value of the field can be obtained through the quick variable $#onfv (old now field value) and through the prefix old when referring to the field value — #old.field_name.

Yes, in codes you can also get the previous value of a field. Where else — in action codes.

Task. Under certain conditions, leave the field value unchanged, but if the conditions are not met — calculate:

=: if(condition: #type = 1; then: $#onfv; else: $calc)

calc: #value_1 * #value_2

= : if(condition: $#onfv = true; then: false; else: true)

For example, to track any changes in the row. Changing any field will lead to the recalculation of the row, and the recalculation of the row will lead to the change of the checkbox.

Thus, you can attach an action code that tracks any changes.

Quite often, a field calculated by code based on another field can be changed, and this change should lead to a change in the main field and should not result in fixing the current value:

For example, the code:

=: select(table: 'table'; field: 'field'; where: 'id' = #num)

The action code for changing this field:

=: set(table: 'table'; field: 'field' = $#nfv; where: 'id' = #num)

But this leads to pin of the current field and the appearance of the hand icon.

The hand icon can be hidden purely cosmetically in the formatting:

f1=: setFormat(showhand: false)

But this will not unpin the value in the field. To make it work correctly, you need to perform a clear as the second action:

a1=: set(table: 'table'; field: 'field' = $#nfv; where: 'id' = #num)

a2=: clear(table: $#ntn; field: $#nf; where: 'id' = #id)

// Don't forget to specify where by the current id

The hand can be hidden exclusively cosmetically in formatting:

f1=: setFormat(showhand: false)