Adds a formula fields ot Advanced Custom Fields that allows you to perform simple math based on field values. From version 1.1 calculations are done while editing fields in the admin screen. When the post is saved, all fields are recalculated before being saved.
Calculated fields adds a new setting “Formula” to the the ACF field editor. Formulas supports referring to other fields in the same Field group using the field name. If a formula is added to a sub field inside a repeater field, the name refers to another sub field in the same repeater.
A sub field inside a repeater field can also refer to a parent field using the “parent.”” prefix (new in version 1.1).
A formula can contain the basic mathematical operations: plus (+), minus (-), multiply (*), division (/) and power of (^). Formulas can also contains functions like sin, cos, arcsin, log, ln, sqrt, abs. Parentheses are supported.
If an expression can’t be evaluated due to invalid syntax or referring to undefined field names, it will silently return zero.
Examples of valid expressions (note, no equal sign at the beginning):
- fieldA * 2
- fieldA * fieldB
- abs(fieldA) * (2 + sqrt(fieldB))
- amount * parent.price
Conditional operators (new in version 1.2.0)</h4)
An expression can also contain a conditional expression that will return either 0 or 1. The supported operators are:
- Equals (==) – Returns 1 when two values are equal, 0 otherwise
- Not equals (!=) – Returns 1 when two values are not equal, 0 otherwise
- Greater than (>) – Returns 1 when the first operand is greater than the second, 0 otherwise
- Less than (<) – Returns 1 when the first operand is less than the second, 0 otherwise
Examples of valid expressions using conditional operators:
- 10 == 10 (returns 1)
- 10 == 2 (returns 0)
- 10 > 2 (returns 1)
- 10 < 2 (returns 0)
Rounding functions (new in version 1.2.0)
Round a decimal value to the nearest integer. Supported functions are:
- round() – Uses standard mathematical rounding rules to round to nearest integer
- ceil() – Rounds the value to the next higher integer
- floor() – Rounds the value to the next lower integer
Examples of valid expressions using rounding functions:
- round(10.2) (returns 10)
- round(10.9) (returns 11)
- round(10.888888 * 10) / 10 (returns 10.9)
- ceil(10.2) (returns 11)
- floor(10.2) (returns 10)
Array functions for repeater fields
If repeater fields are used, a calculated field in the parent field group can summarize a specific repeater sub fields using the aggregation functions sum, count, average, min or max. For example, the expression: “Sum(orderlines.amount)”” will return the sum of all the “amount” fields in the repeater field “orderlines”.
The available array functions are:
Note that anything after the dot (.) in the aggregate expression is an expression in itself. It’s perfectly OK to write a formula like: “Sum(orderlines.price * amount)”. This expression will walk over all lines in the “orderlines” repeater field, perform the calculation “price * amount” and return the sum of all lines.
Note that when working with aggregate functions, parantheses can not be used. If you need to aggregate a more complex calculation, you should add an extra field in the repeater group (hidden if needed) and let the aggregate function work on this extra field.
Data types and calculation order
Calculated fields works with the assumption that all fields are defined as numeric in the ACF editor. Using a text field in a formula WILL PRODUCE UNPREDICTABLE RESULTS.
Calculations are made as the custom field is stored to the database. To minimize the impact of performance, Calculated fields rely on field order. A formula field can only refer to fields ordered BEFORE itself. A formula field that refers to a field ordered after it WILL PRODUCE UNPREDICTABLE RESULTS.
Calculated fields for ACF is a free plugin from wundermatics.com