Struct serde_with::MapPreventDuplicates

pub struct MapPreventDuplicates<K, V>(/* private fields */);

Ensure no duplicate keys exist in a map.

By default serde has a last-value-wins implementation, if duplicate keys for a map 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 keys exist in a map.

The implementation supports both the HashMap and the BTreeMap from the standard library.

Example

#[serde_as]
#[derive(Deserialize)]
struct Doc {
    #[serde_as(as = "MapPreventDuplicates<_, _>")]
    map: HashMap<usize, usize>,
}

// Maps are serialized normally,
let s = r#"{"map": {"1": 1, "2": 2, "3": 3}}"#;
let mut v = Doc {
    map: HashMap::new(),
};
v.map.insert(1, 1);
v.map.insert(2, 2);
v.map.insert(3, 3);
assert_eq!(v, serde_json::from_str(s).unwrap());

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

Trait Implementations

impl<'de, K, V, KAs, VAs> DeserializeAs<'de, BTreeMap<K, V>> for MapPreventDuplicates<KAs, VAs>

where KAs: DeserializeAs<'de, K>, VAs: DeserializeAs<'de, V>, K: Ord,

fn deserialize_as<D>(deserializer: D) -> Result<BTreeMap<K, V>, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'de, K, V, KAs, VAs, S> DeserializeAs<'de, HashMap<K, V, S>> for MapPreventDuplicates<KAs, VAs>

where KAs: DeserializeAs<'de, K>, VAs: DeserializeAs<'de, V>, K: Eq + Hash, S: BuildHasher + Default,

fn deserialize_as<D>(deserializer: D) -> Result<HashMap<K, V, S>, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'de, K, V, KAs, VAs, S> DeserializeAs<'de, HashMap<K, V, S>> for MapPreventDuplicates<KAs, VAs>

where KAs: DeserializeAs<'de, K>, VAs: DeserializeAs<'de, V>, K: Eq + Hash, S: BuildHasher + Default,

fn deserialize_as<D>( deserializer: D ) -> Result<HashbrownMap014<K, V, S>, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'de, K, V, KAs, VAs, S> DeserializeAs<'de, IndexMap<K, V, S>> for MapPreventDuplicates<KAs, VAs>

where KAs: DeserializeAs<'de, K>, VAs: DeserializeAs<'de, V>, K: Eq + Hash, S: BuildHasher + Default,

fn deserialize_as<D>(deserializer: D) -> Result<IndexMap2<K, V, S>, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'de, K, V, KAs, VAs, S> DeserializeAs<'de, IndexMap<K, V, S>> for MapPreventDuplicates<KAs, VAs>

where KAs: DeserializeAs<'de, K>, VAs: DeserializeAs<'de, V>, K: Eq + Hash, S: BuildHasher + Default,

fn deserialize_as<D>(deserializer: D) -> Result<IndexMap<K, V, S>, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<K, V, KA, VA> JsonSchemaAs<BTreeMap<K, V>> for MapPreventDuplicates<KA, VA>

where VA: JsonSchemaAs<V>,

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<K, V, S, KA, VA> JsonSchemaAs<HashMap<K, V, S>> for MapPreventDuplicates<KA, VA>

where VA: JsonSchemaAs<V>,

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<K, V, S, KA, VA> JsonSchemaAs<HashMap<K, V, S>> for MapPreventDuplicates<KA, VA>

where VA: JsonSchemaAs<V>,

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<K, V, S, KA, VA> JsonSchemaAs<IndexMap<K, V, S>> for MapPreventDuplicates<KA, VA>

where VA: JsonSchemaAs<V>,

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<K, V, S, KA, VA> JsonSchemaAs<IndexMap<K, V, S>> for MapPreventDuplicates<KA, VA>

where VA: JsonSchemaAs<V>,

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<K, KAs, V, VAs> SerializeAs<BTreeMap<K, V>> for MapPreventDuplicates<KAs, VAs>

where KAs: SerializeAs<K>, VAs: SerializeAs<V>,

fn serialize_as<S>( value: &BTreeMap<K, V>, serializer: S ) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl<K, KAs, V, VAs, H> SerializeAs<HashMap<K, V, H>> for MapPreventDuplicates<KAs, VAs>

where KAs: SerializeAs<K>, VAs: SerializeAs<V>, H: ?Sized + Sized,

fn serialize_as<S>( value: &HashbrownMap014<K, V, H>, serializer: S ) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl<K, KAs, V, VAs, H> SerializeAs<HashMap<K, V, H>> for MapPreventDuplicates<KAs, VAs>

where KAs: SerializeAs<K>, VAs: SerializeAs<V>, H: ?Sized + Sized,

fn serialize_as<S>( value: &HashMap<K, V, H>, serializer: S ) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl<K, KAs, V, VAs, H> SerializeAs<IndexMap<K, V, H>> for MapPreventDuplicates<KAs, VAs>

where KAs: SerializeAs<K>, VAs: SerializeAs<V>, H: ?Sized + Sized,

fn serialize_as<S>( value: &IndexMap<K, V, H>, serializer: S ) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl<K, KAs, V, VAs, H> SerializeAs<IndexMap<K, V, H>> for MapPreventDuplicates<KAs, VAs>

where KAs: SerializeAs<K>, VAs: SerializeAs<V>, H: ?Sized + Sized,

fn serialize_as<S>( value: &IndexMap2<K, V, H>, serializer: S ) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.