serde_with v2.3.1

Fixed

• Undo the changes to the trait bound for Seq. (#570, #571)
  The new implementation caused issues with serialization formats that require the sequence length beforehand.
  It also caused problems, that certain attributes which worked before no longer worked, due to mismatching number of references.

  Thanks to @stefunctional for reporting and for @stephaneyfx for providing a test case.

serde_with v2.3.0

Added

• Add serde_as compatible versions for the existing duplicate key and value handling. (#534)
  The new types MapPreventDuplicates, MapFirstKeyWins, SetPreventDuplicates, and SetLastValueWins can replace the existing modules maps_duplicate_key_is_error, maps_first_key_wins, sets_duplicate_value_is_error, and sets_last_value_wins.

• Added a new KeyValueMap type using the map key as a struct field. (#341)
  This conversion is useful for maps, where an ID value is the map key, but the ID should become part of a single struct.
  The conversion allows this, by using a special field named $key$.

  This conversion is possible for structs and maps, using the $key$ field.
  Tuples, tuple structs, and sequences are supported by turning the first value into the map key.

  Each of the SimpleStructs

  // Somewhere there is a collection:
  // #[serde_as(as = "KeyValueMap<_>")]
  // Vec<SimpleStruct>,
  
  #[derive(Serialize, Deserialize)]
  struct SimpleStruct {
      b: bool,
      // The field named `$key$` will become the map key
      #[serde(rename = "$key$")]
      id: String,
      i: i32,
  }

  will turn into a JSON snippet like this.

  "id-0000": {
    "b": false,
    "i": 123
  },

Changed

• Relax the trait bounds of Seq to allow for more custom types. (#565)
  This extends the support beyond tuples.

Fixed

• EnumMap passes the human_readable status of the Serializer to more places.
• Support alloc on targets without target_has_atomic = "ptr". (#560)
  Thanks to @vembacher for reporting and fixing the issue.

serde_with v2.2.0

Added

• Add new Map and Seq types for converting between maps and tuple lists. (#527)

  The behavior is not new, but already present using BTreeMap/HashMap or Vec.
  However, the new types Map and Seq are also available on no_std, even without the alloc feature.

Changed

• Pin the serde_with_macros dependency to the same version as the main crate.
  This simplifies publishing and ensures that always a compatible version is picked.

Fixed

• serde_with::apply had an issue matching types when invisible token groups where in use (#538)
  The token groups can stem from macro_rules expansion, but should be treated mostly transparent.
  The old code required a group to match a group, while now groups are silently removed when checking for type patterns.

serde_with v2.1.0

Added

• Add new apply attribute to simplify repetitive attributes over many fields.
  Multiple rules and multiple attributes can be provided each.

  #[serde_with::apply(
      Option => #[serde(default)] #[serde(skip_serializing_if = "Option::is_none")],
      Option<bool> => #[serde(rename = "bool")],
  )]
  #[derive(serde::Serialize)]
  struct Data {
      a: Option<String>,
      b: Option<u64>,
      c: Option<String>,
      d: Option<bool>,
  }

  The apply attribute will expand into this, applying the attributs to the matching fields:

  #[derive(serde::Serialize)]
  struct Data {
      #[serde(default)]
      #[serde(skip_serializing_if = "Option::is_none")]
      a: Option<String>,
      #[serde(default)]
      #[serde(skip_serializing_if = "Option::is_none")]
      b: Option<u64>,
      #[serde(default)]
      #[serde(skip_serializing_if = "Option::is_none")]
      c: Option<String>,
      #[serde(default)]
      #[serde(skip_serializing_if = "Option::is_none")]
      #[serde(rename = "bool")]
      d: Option<bool>,
  }

  The attribute supports field matching using many rules, such as _ to apply to all fields and partial generics like Option to match any Option be it Option<String>, Option<bool>, or Option<T>.

Fixed

• The derive macros SerializeDisplay and DeserializeFromStr now take better care not to use conflicting names for generic values. (#526)
  All used generics now start with __ to make conflicts with manually written code unlikely.

  Thanks to @Elrendio for submitting a PR fixing the issue.

serde_with_macros v2.1.0

Added

• Add new apply attribute to simplify repetitive attributes over many fields.
  Multiple rules and multiple attributes can be provided each.

  #[serde_with::apply(
      Option => #[serde(default)] #[serde(skip_serializing_if = "Option::is_none")],
      Option<bool> => #[serde(rename = "bool")],
  )]
  #[derive(serde::Serialize)]
  struct Data {
      a: Option<String>,
      b: Option<u64>,
      c: Option<String>,
      d: Option<bool>,
  }

  The apply attribute will expand into this, applying the attributs to the matching fields:

  #[derive(serde::Serialize)]
  struct Data {
      #[serde(default)]
      #[serde(skip_serializing_if = "Option::is_none")]
      a: Option<String>,
      #[serde(default)]
      #[serde(skip_serializing_if = "Option::is_none")]
      b: Option<u64>,
      #[serde(default)]
      #[serde(skip_serializing_if = "Option::is_none")]
      c: Option<String>,
      #[serde(default)]
      #[serde(skip_serializing_if = "Option::is_none")]
      #[serde(rename = "bool")]
      d: Option<bool>,
  }

  The attribute supports field matching using many rules, such as _ to apply to all fields and partial generics like Option to match any Option be it Option<String>, Option<bool>, or Option<T>.

Fixed

• The derive macros SerializeDisplay and DeserializeFromStr now take better care not to use conflicting names for generic values. (#526)
  All used generics now start with __ to make conflicts with manually written code unlikely.

  Thanks to @Elrendio for submitting a PR fixing the issue.

serde_with v2.0.1

Added

• time added support for the well-known Iso8601 format.
  This extends the existing support of Rfc2822 and Rfc3339.

Changed

• Warn if serde_as is used on an enum variant.
  Attributes on enum variants were never supported.
  But #[serde(with = "...")] can be added on variants, such that some confusion can occur when migration (#499).

Note

A cargo bug (cargo#10801) means that upgrading from v1 to v2 may add unnecessary crates to the Cargo.lock file.
A diff of the lock-file makes it seem that serde_with depends on new crates, even though these crates are unused and will not get compiled or linked.
However, tools consuming Cargo.lock or cargo metadata might give wrong results.

serde_with_macros v2.0.1

Changed

• Warn if serde_as is used on an enum variant.
  Attributes on enum variants were never supported.
  But #[serde(with = "...")] can be added on variants, such that some confusion can occur when migration (#499).

serde_with v2.0.0

Added

• Make JsonString<T> smarter by allowing nesting serde_as definitions.
  This allows applying custom serialization logic, before the value gets converted into a JSON string.

  // Rust
  #[serde_as(as = "JsonString<Vec<(JsonString, _)>>")]
  value: BTreeMap<[u8; 2], u32>,
  
  // JSON
  {"value":"[[\"[1,2]\",3],[\"[4,5]\",6]]"}

Changed

• Make #[serde_as] behave more intuitive on Option<T> fields.

  The #[serde_as] macro now detects if a #[serde_as(as = "Option<S>")] is used on a field of type Option<T> and applies #[serde(default)] to the field.
  This restores the ability to deserialize with missing fields and fixes a common annoyance (#183, #185, #311, #417).
  This is a breaking change, since now deserialization will pass where it did not before and this might be undesired.

  The Option field and transformation are detected by directly matching on the type name.
  These variants are detected as Option.

  • Option
  • std::option::Option, with or without leading ::
  • core::option::Option, with or without leading ::

  If an existing default attribute is detected, the attribute is not applied again.
  This behavior can be suppressed by using #[serde_as(no_default)] or #[serde_as(as = "Option<S>", no_default)].

• NoneAsEmptyString and string_empty_as_none use a different serialization bound (#388).

  Both types used AsRef<str> as the serialization bound.
  This is limiting for non-string types like Option<i32>.
  The deserialization often was already more flexible, due to the FromStr bound.

  For most std types this should have little impact, as the types implementing AsRef<str> mostly implement Display, too, such as String, Cow<str>, or Rc<str>.

• Bump MSRV to 1.60. This is required for the optional dependency feature syntax in cargo.

Removed

• Remove old module based conversions.

  The newer serde_as based conversions are preferred.

  • seq_display_fromstr: Use DisplayFromStr in combination with your container type:

    #[serde_as(as = "BTreeSet<DisplayFromStr>")]
    addresses: BTreeSet<Ipv4Addr>,
    #[serde_as(as = "Vec<DisplayFromStr>")]
    bools: Vec<bool>,

  • tuple_list_as_map: Use BTreeMap on a Vec of tuples:

    #[serde_as(as = "BTreeMap<_, _>")] // HashMap will also work
    s: Vec<(i32, String)>,

  • map_as_tuple_list can be replaced with #[serde_as(as = "Vec<(_, _)>")].

  • display_fromstr can be replaced with #[serde_as(as = "DisplayFromStr")].

  • bytes_or_string can be replaced with #[serde_as(as = "BytesOrString")].

  • default_on_error can be replaced with #[serde_as(as = "DefaultOnError")].

  • default_on_null can be replaced with #[serde_as(as = "DefaultOnNull")].

  • string_empty_as_none can be replaced with #[serde_as(as = "NoneAsEmptyString")].

  • StringWithSeparator can now only be used in serde_as.
    The definition of the Separator trait and its implementations have been moved to the formats module.

  • json::nested can be replaced with #[serde_as(as = "json::JsonString")].

• Remove previously deprecated modules.

  • sets_first_value_wins
  • btreemap_as_tuple_list and hashmap_as_tuple_list can be replaced with #[serde_as(as = "Vec<(_, _)>")].

serde_with_macros v2.0.0

No changes compared to v2.0.0-rc.0.

Changed

• Make #[serde_as] behave more intuitive on Option<T> fields.

  The #[serde_as] macro now detects if a #[serde_as(as = "Option<S>")] is used on a field of type Option<T> and applies #[serde(default)] to the field.
  This restores the ability to deserialize with missing fields and fixes a common annoyance (#183, #185, #311, #417).
  This is a breaking change, since now deserialization will pass where it did not before and this might be undesired.

  The Option field and transformation are detected by directly matching on the type name.
  These variants are detected as Option.

  • Option
  • std::option::Option, with or without leading ::
  • core::option::Option, with or without leading ::

  If an existing default attribute is detected, the attribute is not applied again.
  This behavior can be supressed by using #[serde_as(no_default)] or #[serde_as(as = "Option<S>", no_default)].

Fixed

• Make the documentation clearer by stating that the #[serde_as] and #[skip_serializing_none] attributes must always be placed before #[derive].

serde_with v2.0.0-rc.0

Changed

• Make #[serde_as] behave more intuitive on Option<T> fields.

  The #[serde_as] macro now detects if a #[serde_as(as = "Option<S>")] is used on a field of type Option<T> and applies #[serde(default)] to the field.
  This restores the ability to deserialize with missing fields and fixes a common annoyance (#183, #185, #311, #417).
  This is a breaking change, since now deserialization will pass where it did not before and this might be undesired.

  The Option field and transformation are detected by directly matching on the type name.
  These variants are detected as Option.

  • Option
  • std::option::Option, with or without leading ::
  • core::option::Option, with or without leading ::

  If an existing default attribute is detected, the attribute is not applied again.
  This behavior can be suppressed by using #[serde_as(no_default)] or #[serde_as(as = "Option<S>", no_default)].

• NoneAsEmptyString and string_empty_as_none use a different serialization bound (#388).

  Both types used AsRef<str> as the serialization bound.
  This is limiting for non-string types like Option<i32>.
  The deserialization often was already more flexible, due to the FromStr bound.

  For most std types this should have little impact, as the types implementing AsRef<str> mostly implement Display, too, such as String, Cow<str>, or Rc<str>.

• Bump MSRV to 1.60. This is required for the optional dependency feature syntax in cargo.

Removed

• Remove old module based conversions.

  The newer serde_as based conversions are preferred.

  • seq_display_fromstr: Use DisplayFromStr in combination with your container type:

    #[serde_as(as = "BTreeSet<DisplayFromStr>")]
    addresses: BTreeSet<Ipv4Addr>,
    #[serde_as(as = "Vec<DisplayFromStr>")]
    bools: Vec<bool>,

  • tuple_list_as_map: Use BTreeMap on a Vec of tuples:

    #[serde_as(as = "BTreeMap<_, _>")] // HashMap will also work
    s: Vec<(i32, String)>,

  • map_as_tuple_list can be replaced with #[serde_as(as = "Vec<(_, _)>")].

  • display_fromstr can be replaced with #[serde_as(as = "DisplayFromStr")].

  • bytes_or_string can be replaced with #[serde_as(as = "BytesOrString")].

  • default_on_error can be replaced with #[serde_as(as = "DefaultOnError")].

  • default_on_null can be replaced with #[serde_as(as = "DefaultOnNull")].

  • string_empty_as_none can be replaced with #[serde_as(as = "NoneAsEmptyString")].

  • StringWithSeparator can now only be used in serde_as.
    The definition of the Separator trait and its implementations have been moved to the formats module.

  • json::nested can be replaced with #[serde_as(as = "json::JsonString")].

• Remove previously deprecated modules.

  • sets_first_value_wins
  • btreemap_as_tuple_list and hashmap_as_tuple_list can be replaced with #[serde_as(as = "Vec<(_, _)>")].