Attributes

Attributes are used to customize the Deserr implementations produced by deserr's derive.

There are three categories of attributes:

Container attributes — apply to a struct or enum declaration.
Variant attributes — apply to a variant of an enum.
Field attributes — apply to one field in a struct or in an enum variant.

use deserr::Deserr;

#[derive(Deserr)]
#[deserr(deny_unknown_fields)]  // <-- this is a container attribute
struct S {
    #[deserr(default)]  // <-- this is a field attribute
    f: i32,
}

#[derive(Deserr)]
#[deserr(rename_all = camelCase)]  // <-- this is also a container attribute
enum E {
    #[deserr(rename = "_deserr")]  // <-- this is a variant attribute
    DeserrIsGreat,
    SerdeIsAwesome
}

fn main() {}

Note that a single struct, enum, variant, or field may have multiple attributes on it.

Feature comparison table with serde

Datastructure support

datastructure	serde	deserr
Struct	yes	yes
Tuple struct	yes	no
Untagged Enum	yes	no
Untagged unit Enum	yes	yes
Tagged Enum	yes	yes

Container attributes

features	serde	deserr	note
rename	yes	no
rename_all	yes	yes
deny_unknown_fields	yes	yes	With deserr you can call a custom function when an unknown field is encountered
tag	yes	yes
tag+content	yes	no
untagged	yes	no	it's only supported for unit enums
bound	yes	no	Can be emulated with `where_predicate`
default	yes	no
remote	yes	no
transparent	yes	no
from	yes	yes
try_from	yes	yes
into	yes	no
crate	yes	no
validate	no	yes	Allows you to validate the content of struct after it has been deserialized
error	no	yes	Specify the error type that should be used while deserializing this structure
where_predicate	no	yes	Let you add where clauses to the generated `Deserr` implementation

Field attributes

features	serde	deserr	note
rename	yes	yes
alias	yes	no
default	yes	yes
flatten	yes	no	serde doesn't support flattening + denying unknown field
skip	yes	yes
deserialize_with	yes	no	But it's kinda emulated with `from` and `try_from`
with	yes	no
borrow	yes	no	deserr does not support types with references
bound	yes	no
map	no	yes	Allows you to map the value after it was deserialized
from	no	yes	Deserialize this field from an infallible function
try_from	no	yes	Deserialize this field from a fallible function
missing_field_error	no	yes	Allows you to return a custom error if this field is missing
error	no	yes	Specify the error type that should be used while deserializing this field