Struct JsonDeserializer 

pub struct JsonDeserializer<'a> { /* private fields */ }

JSON deserializer that implements the ShapeDeserializer trait.

Implementations

impl<'a> JsonDeserializer<'a>

pub fn position(&self) -> usize

Returns the current byte offset relative to the input slice supplied at construction.

Calling this method does not advance the deserializer.

impl<'a> JsonDeserializer<'a>

pub fn read_discriminated_document( &mut self, ) -> Result<DiscriminatedDocument, SerdeError>

Reads a JSON document from the input, lifts an optional top-level __type field into the result’s discriminator slot, and attaches the codec’s [DocumentSettings] to the result so downstream accessors like DiscriminatedDocument::as_blob and DiscriminatedDocument::as_timestamp can perform JSON-specific coercion (base64-decoded blobs, format-aware timestamps).

__type discriminator lift

When the parsed top-level value is a JSON object containing a __type key whose value is an absolute Smithy shape ID (namespace#ShapeName), the lift extracts that ID into the resulting [DiscriminatedDocument]’s discriminator slot and drops the key from the result map.

Falls back to leaving __type in the map when the value is not a string, or is a relative shape name (no #) and no default_namespace is configured. When a default_namespace is set, a relative name is resolved against it before lifting.

Example

use aws_smithy_json::codec::JsonCodec;
use aws_smithy_schema::codec::Codec;

let codec = JsonCodec::default();
let bytes = br#"{"__type":"smithy.example#Bird","name":"Iago"}"#;
let mut deser = codec.create_deserializer(bytes);
let doc = deser.read_discriminated_document().unwrap();

// `__type` was lifted into the discriminator slot.
assert_eq!(doc.discriminator(), Some("smithy.example#Bird"));

// The map no longer contains `__type`.
let map = doc.document().as_object().unwrap();
assert_eq!(map.len(), 1);
assert_eq!(map.get("name").and_then(|d| d.as_string()), Some("Iago"));

Trait Implementations

impl<'a> ShapeDeserializer for JsonDeserializer<'a>

fn skip_value(&mut self) -> Result<(), SerdeError>

JSON shares one cursor across the whole object, so declining a value still has to move past it. Delegates to the same validating skip used for unknown members: a body copy of a transport-bound member is discarded, but it must still be well-formed JSON, so malformed content is reported rather than stepped over.

fn read_struct( &mut self, schema: &Schema<'_>, consumer: &mut dyn FnMut(&Schema<'_>, &mut dyn ShapeDeserializer) -> Result<(), SerdeError>, ) -> Result<(), SerdeError>

Reads a structure from the deserializer.

fn read_list( &mut self, _schema: &Schema<'_>, consumer: &mut dyn FnMut(&mut dyn ShapeDeserializer) -> Result<(), SerdeError>, ) -> Result<(), SerdeError>

Reads a list from the deserializer.

fn read_map( &mut self, _schema: &Schema<'_>, consumer: &mut dyn FnMut(String, &mut dyn ShapeDeserializer) -> Result<(), SerdeError>, ) -> Result<(), SerdeError>

Reads a map from the deserializer.

fn read_boolean(&mut self, _schema: &Schema<'_>) -> Result<bool, SerdeError>

Reads a boolean value.

fn read_byte(&mut self, _schema: &Schema<'_>) -> Result<i8, SerdeError>

Reads a byte (i8) value.

fn read_short(&mut self, _schema: &Schema<'_>) -> Result<i16, SerdeError>

Reads a short (i16) value.

fn read_integer(&mut self, _schema: &Schema<'_>) -> Result<i32, SerdeError>

Reads an integer (i32) value.

fn read_long(&mut self, _schema: &Schema<'_>) -> Result<i64, SerdeError>

Reads a long (i64) value.

fn read_float(&mut self, _schema: &Schema<'_>) -> Result<f32, SerdeError>

Reads a float (f32) value.

fn read_double(&mut self, _schema: &Schema<'_>) -> Result<f64, SerdeError>

Reads a double (f64) value.

fn read_big_integer( &mut self, _schema: &Schema<'_>, ) -> Result<BigInteger, SerdeError>

Reads a big integer value.

fn read_big_decimal( &mut self, _schema: &Schema<'_>, ) -> Result<BigDecimal, SerdeError>

Reads a big decimal value.

fn read_string(&mut self, _schema: &Schema<'_>) -> Result<String, SerdeError>

Reads a string value.

fn read_blob(&mut self, _schema: &Schema<'_>) -> Result<Blob, SerdeError>

Reads a blob (byte array) value.

fn read_string_list( &mut self, _schema: &Schema<'_>, ) -> Result<Vec<String>, SerdeError>

Reads a list of strings.

fn read_blob_list( &mut self, _schema: &Schema<'_>, ) -> Result<Vec<Blob>, SerdeError>

Reads a list of blobs.

fn read_integer_list( &mut self, _schema: &Schema<'_>, ) -> Result<Vec<i32>, SerdeError>

Reads a list of integers.

fn read_long_list( &mut self, _schema: &Schema<'_>, ) -> Result<Vec<i64>, SerdeError>

Reads a list of longs.

fn read_string_string_map( &mut self, _schema: &Schema<'_>, ) -> Result<HashMap<String, String>, SerdeError>

Reads a map with string values.

fn read_timestamp( &mut self, schema: &Schema<'_>, ) -> Result<DateTime, SerdeError>

Reads a timestamp value.

fn read_document( &mut self, _schema: &Schema<'_>, ) -> Result<Document, SerdeError>

Reads a document value.

fn is_null(&self) -> bool

Checks if the current value is null.

fn read_null(&mut self) -> Result<(), SerdeError>

Consumes a null value, advancing past it.

fn container_size(&self) -> Option<usize>

Returns the size of the current container if known.