# add_overridable_auth_handler · FT4 Rell API · Chromia Docs (concept)

> function add_ overridable_ auth_ handler(scope: text, flags: list<text>, message: (gtv) -> text?, resolver: (gtv, byte_ array, list<byte_ array>) -> byte_ 

Source: https://docs.chromia.com/pages/ft4-rell/-f-t4-library/lib.ft4.core.auth/add_overridable_auth_handler/

FUNCTION

# add\_overridable\_auth\_handler

```signature
function add_overridable_auth_handler(scope: text, flags: list<text>, message: (gtv) -> text?, resolver: (gtv, byte_array, list<byte_array>) -> byte_array??): map<text, _auth_handler>
```

[Source](https://gitlab.com/chromaway/ft4-lib/-/blob/development/rell/src/lib/ft4/core/auth/module.rell#lines-282)

Like `add_auth_handler`, but the auth handler here defined will not be used if a different
auth handler for the same scope was created with `add_auth_handler`.

As normal, however, for an operation with mount point `a.b.operation`, an overridable auth
handler with scope `a.b` will take precedence over a non-overridable auth handler with
scope `a`

Throws if `scope` is not valid

**Parameters**

* **scope** — The scope of the auth handler - either an operation name or a mount point
* **message** — The `message` parameter of the auth handler
* **resolver** — The `resolver` parameter of the auth handler

**See Also**

* [\_auth\_handler](https://docs.chromia.com/pages/ft4-rell/-f-t4-library/lib.ft4.core.auth/_auth_handler/) — for more information on `flags`, `message` and `resolver`
* [add\_auth\_handler](https://docs.chromia.com/pages/ft4-rell/-f-t4-library/lib.ft4.core.auth/add_auth_handler/) — for a usage example
* [get\_auth\_handler](https://docs.chromia.com/pages/ft4-rell/-f-t4-library/lib.ft4.core.auth/get_auth_handler/) — for a definition of auth handler scope

[View this page on docs.chromia.com](https://docs.chromia.com/pages/ft4-rell/-f-t4%20-library/lib.ft4.core.auth/add_overridable_auth_handler.html)Generated API reference, mirrored from the live docs