# runtime-struct-field-names-as-array
[](https://crates.io/crates/runtime_struct_field_names_as_array)
[](https://docs.rs/runtime_struct_field_names_as_array)
[](https://github.com/0cv/runtime_struct_field_names_as_array/actions/workflows/rust.yml)
Provides the `FieldNamesAsArray` procedural macro.
The macro adds the fn `field_names_as_array()` to the struct the macro is derived on. It contains the field names of the given
struct, including the parents
**Note:** The macro can only be derived from named structs.
**IMPORTANT** This crate has a runtime overhead while it has limited options. If you do NOT intend to use it on a nested struct, you shall use this [crate](https://github.com/jofas/struct_field_names_as_array) instead. See [discussion](https://github.com/jofas/struct_field_names_as_array/issues/4)
## Table of Contents
* [Usage](#usage)
* [Attributes](#attributes)
* [Field Attributes](#field-attributes)
* [Flatten](#flatten)
## Usage
You can derive the `FieldNamesAsArray` macro like this:
```rust
use runtime_struct_field_names_as_array::FieldNamesAsArray;
#[derive(FieldNamesAsArray)]
struct Foo {
bar: String,
baz: String,
bat: String,
}
assert_eq!(Foo::field_names_as_array(), ["bar", "baz", "bat"]);
```
## Attributes
The `FieldNamesAsArray` macro supports the
`field_names_as_array` attribute.
`field_names_as_array` can be applied to a field with only the `flatten` attribute
### Container Attributes
Container attributes are global attributes that change the behavior
of the whole field names array, rather than that of a single field.
### Field Attributes
Field attributes can be added to the fields of a named struct and
change the behavior of a single field.
#### Flatten
The `flatten` attribute will add the parent fields. Option struct are also supported. If the attribute is not added on a struct type, it will be considered as a regular field.
```rust
use runtime_struct_field_names_as_array::FieldNamesAsArray;
#[derive(FieldNamesAsArray)]
struct Parent {
foo: String,
}
#[derive(FieldNamesAsArray)]
struct Foo {
bar: String,
baz: String,
#[field_names_as_array(flatten)]
parent: Parent,
#[field_names_as_array(flatten)]
parent_option: Option<Parent>,
another_parent: Parent,
}
assert_eq!(Foo::field_names_as_array(), ["bar", "baz", "parent.foo", "parent_option.foo", "another_parent"]);
```