Struct SetPreventDuplicates

pub struct SetPreventDuplicates<T>(/* private fields */);

Ensure no duplicate values exist in a set.

By default serde has a last-value-wins implementation, if duplicate values for a set exist. Sometimes it is desirable to know when such an event happens, as the first value is overwritten and it can indicate an error in the serialized data.

This helper returns an error if two identical values exist in a set.

The implementation supports both the HashSet and the BTreeSet from the standard library.

Example

#[serde_as]
#[derive(Deserialize)]
struct Doc {
    #[serde_as(as = "SetPreventDuplicates<_>")]
    set: HashSet<usize>,
}

// Sets are serialized normally,
let s = r#"{"set": [1, 2, 3, 4]}"#;
let v = Doc {
    set: HashSet::from_iter(vec![1, 2, 3, 4]),
};
assert_eq!(v, serde_json::from_str(s).unwrap());

// but create an error if duplicate values, like the `1`, exist.
let s = r#"{"set": [1, 2, 3, 4, 1]}"#;
let res: Result<Doc, _> = serde_json::from_str(s);
assert!(res.is_err());

Trait Implementations

impl<'de, T, TAs> DeserializeAs<'de, BTreeSet<T>> for SetPreventDuplicates<TAs>

where TAs: DeserializeAs<'de, T>, T: Ord,

fn deserialize_as<D>(deserializer: D) -> Result<BTreeSet<T>, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'de, T, TAs, S> DeserializeAs<'de, HashSet<T, S>> for SetPreventDuplicates<TAs>

where TAs: DeserializeAs<'de, T>, T: Eq + Hash, S: BuildHasher + Default,

fn deserialize_as<D>(deserializer: D) -> Result<HashSet<T, S>, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'de, T, TAs, S> DeserializeAs<'de, HashSet<T, S>> for SetPreventDuplicates<TAs>

where TAs: DeserializeAs<'de, T>, T: Eq + Hash, S: BuildHasher + Default,

fn deserialize_as<D>(deserializer: D) -> Result<HashbrownSet014<T, S>, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'de, T, TAs, S> DeserializeAs<'de, HashSet<T, S>> for SetPreventDuplicates<TAs>

where TAs: DeserializeAs<'de, T>, T: Eq + Hash, S: BuildHasher + Default,

fn deserialize_as<D>(deserializer: D) -> Result<HashbrownSet015<T, S>, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'de, T, TAs, S> DeserializeAs<'de, IndexSet<T, S>> for SetPreventDuplicates<TAs>

where TAs: DeserializeAs<'de, T>, T: Eq + Hash, S: BuildHasher + Default,

fn deserialize_as<D>(deserializer: D) -> Result<IndexSet<T, S>, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'de, T, TAs, S> DeserializeAs<'de, IndexSet<T, S>> for SetPreventDuplicates<TAs>

where TAs: DeserializeAs<'de, T>, T: Eq + Hash, S: BuildHasher + Default,

fn deserialize_as<D>(deserializer: D) -> Result<IndexSet2<T, S>, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<T, TA> JsonSchemaAs<T> for SetPreventDuplicates<TA>

where TA: JsonSchemaAs<T>,

Available on crate feature schemars_0_8 only.

fn schema_name() -> String

The name of the generated JSON Schema.

fn schema_id() -> Cow<'static, str>

Returns a string that uniquely identifies the schema produced by this type.

fn json_schema(gen: &mut SchemaGenerator) -> Schema

Generates a JSON Schema for this type.

fn is_referenceable() -> bool

Whether JSON Schemas generated for this type should be re-used where possible using the $ref keyword.

impl<T, TAs> SerializeAs<BTreeSet<T>> for SetPreventDuplicates<TAs>

where TAs: SerializeAs<T>,

fn serialize_as<S>( value: &BTreeSet<T>, serializer: S, ) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl<T, TAs, H> SerializeAs<HashSet<T, H>> for SetPreventDuplicates<TAs>

where TAs: SerializeAs<T>, H: ?Sized + Sized,

fn serialize_as<S>( value: &HashSet<T, H>, serializer: S, ) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl<T, TAs, H> SerializeAs<HashSet<T, H>> for SetPreventDuplicates<TAs>

where TAs: SerializeAs<T>, H: ?Sized + Sized,

fn serialize_as<S>( value: &HashbrownSet014<T, H>, serializer: S, ) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl<T, TAs, H> SerializeAs<HashSet<T, H>> for SetPreventDuplicates<TAs>

where TAs: SerializeAs<T>, H: ?Sized + Sized,

fn serialize_as<S>( value: &HashbrownSet015<T, H>, serializer: S, ) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl<T, TAs, H> SerializeAs<IndexSet<T, H>> for SetPreventDuplicates<TAs>

where TAs: SerializeAs<T>, H: ?Sized + Sized,

fn serialize_as<S>( value: &IndexSet<T, H>, serializer: S, ) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl<T, TAs, H> SerializeAs<IndexSet<T, H>> for SetPreventDuplicates<TAs>

where TAs: SerializeAs<T>, H: ?Sized + Sized,

fn serialize_as<S>( value: &IndexSet2<T, H>, serializer: S, ) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.