| --- |
| page_title: coalesce - Functions - Configuration Language |
| description: |- |
| The coalesce function takes any number of arguments and returns the |
| first one that isn't null nor empty. |
| --- |
| |
| # `coalesce` Function |
| |
| `coalesce` takes any number of arguments and returns the first one |
| that isn't null or an empty string. |
| |
| All of the arguments must be of the same type. Terraform will try to |
| convert mismatched arguments to the most general of the types that all |
| arguments can convert to, or return an error if the types are incompatible. |
| The result type is the same as the type of all of the arguments. |
| |
| ## Examples |
| |
| ``` |
| > coalesce("a", "b") |
| a |
| > coalesce("", "b") |
| b |
| > coalesce(1,2) |
| 1 |
| ``` |
| |
| To perform the `coalesce` operation with a list of strings, use the `...` |
| symbol to expand the list as arguments: |
| |
| ``` |
| > coalesce(["", "b"]...) |
| b |
| ``` |
| |
| Terraform attempts to select a result type that all of the arguments can |
| convert to, so mixing argument types may produce surprising results due to |
| Terraform's automatic type conversion rules: |
| |
| ``` |
| > coalesce(1, "hello") |
| "1" |
| > coalesce(true, "hello") |
| "true" |
| > coalesce({}, "hello") |
| |
| Error: Error in function call |
| |
| Call to function "coalesce" failed: all arguments must have the same type. |
| ``` |
| |
| ## Related Functions |
| |
| * [`coalescelist`](/language/functions/coalescelist) performs a similar operation with |
| list arguments rather than individual arguments. |
