Enum DuplicateKeys 

#[non_exhaustive]
pub enum DuplicateKeys {
    Last,
    First,
    Error,
}

What happens if a key is given more than once.

JSON objects can contain the same key more than once and query strings commonly repeat keys. Where a single value is expected (the field of a struct or an entry of a map) the policy decides what happens. It’s an extension value, usually configured in the Context (or in the State, see set). The default is Error: if the same key could mean different values to different parsers (a proxy might use the first value, the application the last) the input is rejected. Formats can have other defaults (query strings and environment variables use the last value), which the context overrides.

use std::collections::BTreeMap;
use deser::de::DuplicateKeys;
use deser::Context;

type Map = BTreeMap<String, u32>;

let input = r#"{"a": 1, "a": 2}"#;
let err = deser_json::from_str::<Map>(input).unwrap_err();
assert_eq!(err.message(), "duplicate key in map");

let config = deser_json::DeserializerConfig::builder()
    .context(Context::with(DuplicateKeys::Last))
    .build();
assert_eq!(config.from_str::<Map>(input).unwrap()["a"], 2);

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Last

The last value is used.

First

The first value is used, later ones are ignored.

Error

Duplicate keys are rejected.

Implementations

impl DuplicateKeys

pub fn of(state: &State) -> DuplicateKeys

Returns the policy of a deserialization.

pub fn set(self, state: &mut State)

Sets the policy of a deserialization.

pub fn set_default(self, state: &mut State)

Sets the policy unless the state or the context has one.

Formats use this for their default (see State::set_default).

Trait Implementations

impl Clone for DuplicateKeys

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for DuplicateKeys

impl Debug for DuplicateKeys

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for DuplicateKeys

fn default() -> Self

Returns the “default value” for a type.

impl Eq for DuplicateKeys

impl PartialEq for DuplicateKeys

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for DuplicateKeys