Kriskras99 commented on code in PR #477:
URL: https://github.com/apache/avro-rs/pull/477#discussion_r2833594238
##########
avro/src/serde/derive.rs:
##########
@@ -81,6 +85,10 @@ use std::collections::{HashMap, HashSet};
///
/// Set the `doc` attribute of the schema. Defaults to the documentation of
the type.
///
+/// - `#[avro(default = r#"{"field": 42, "other": "Spam"}"#)]`
Review Comment:
The top-level attribute is only used for implementing
`AvroSchemaComponent::field_default`, it is not used to set defaults for the
individual fields.
##########
avro_derive/src/attributes/mod.rs:
##########
@@ -116,12 +118,29 @@ impl NamedTypeOptions {
let doc = avro.doc.or_else(|| extract_rustdoc(attributes));
+ let default = match avro.default {
+ None => quote! { None },
+ Some(default_value) => {
+ let _: serde_json::Value =
+ serde_json::from_str(&default_value[..]).map_err(|e| {
+ vec![syn::Error::new(
+ ident.span(),
+ format!("Invalid avro default json: \n{e}"),
+ )]
+ })?;
+ quote! {
+
Some(serde_json::from_str(#default_value).expect(format!("Invalid JSON: {:?}",
#default_value).as_str()))
Review Comment:
Nope. The first time we parse is during the build. We do that so we can
check the JSON is at least valid.
The second time we parse is when we create the `Schema` at runtime (see the
`quote!` block), which can't reuse the build time parsing because the original
parsing does not exist at runtime.
If you do try this, you get:
```
the trait bound `Value: darling::ToTokens` is not satisfied [E0277]
```
##########
avro/src/serde/derive.rs:
##########
@@ -113,11 +121,14 @@ use std::collections::{HashMap, HashSet};
///
/// Set the `doc` attribute of the field. Defaults to the documentation of
the field.
///
-/// - `#[avro(default = "null")]`
+/// - `#[avro(default = "null")]` or `#[avro(default = false)]`
///
-/// Set the `default` attribute of the field.
+/// Control the `default` attribute of the field. When not used, it will
use [`AvroSchemaComponent::field_default`]
+/// to get the default value for a type. This default value can be
overriden by providing a JSON string.
+/// To remove the `default` attribute for a field, set `default` to `false`.
Review Comment:
If a user wants to set the JSON value `false` it would be `#[avro(default =
"false")]`.
I clearly need to improve the documentation.
##########
avro_derive/src/attributes/mod.rs:
##########
@@ -274,11 +320,11 @@ impl FieldOptions {
}
if ((serde.skip_serializing && !serde.skip_deserializing)
|| serde.skip_serializing_if.is_some())
- && avro.default.is_none()
+ && avro.default == FieldDefault::Disabled
Review Comment:
We unfortunately cannot detect that at compile time, so that will produce an
error at runtime.
##########
avro_derive/tests/derive.rs:
##########
@@ -2377,3 +2378,203 @@ fn avro_rs_448_flatten_field_positions() {
.collect::<Vec<_>>();
assert_eq!(positions.as_slice(), &[0, 1, 2, 3][..]);
}
+
+#[test]
+fn avro_rs_476_field_default() {
+ #[derive(AvroSchema)]
+ struct Bar {
+ _field: Box<Bar>,
+ }
+
+ #[derive(AvroSchema)]
+ #[avro(default = r#"{"_field": true}"#)]
+ struct Spam {
+ _field: bool,
+ }
+
+ #[derive(AvroSchema)]
+ struct Foo {
+ _a: bool,
+ _b: i8,
+ _c: i16,
+ _d: i32,
+ _e: i64,
+ _f: u8,
+ _g: u16,
+ _h: u32,
+ _i: f32,
+ _j: f64,
+ _k: String,
+ _l: Box<str>,
+ _m: char,
+ _n: Box<Spam>,
+ _o: Vec<bool>,
+ _p: [u8; 5],
+ _p_alt: [Bar; 5],
+ _q: HashMap<String, String>,
+ _r: Option<f64>,
+ _s: Duration,
+ _t: Uuid,
+ _u: u64,
+ _v: u128,
+ _w: i128,
+ _x: Bar,
+ }
+
+ let schema = Foo::get_schema();
+ assert_eq!(
+ serde_json::to_string(&schema).unwrap(),
+
r#"{"type":"record","name":"Foo","fields":[{"name":"_a","type":"boolean","default":false},{"name":"_b","type":"int","default":0},{"name":"_c","type":"int","default":0},{"name":"_d","type":"int","default":0},{"name":"_e","type":"long","default":0},{"name":"_f","type":"int","default":0},{"name":"_g","type":"int","default":0},{"name":"_h","type":"long","default":0},{"name":"_i","type":"float","default":0.0},{"name":"_j","type":"double","default":0.0},{"name":"_k","type":"string","default":""},{"name":"_l","type":"string","default":""},{"name":"_m","type":"string","default":"\u0000"},{"name":"_n","type":{"type":"record","name":"Spam","fields":[{"name":"_field","type":"boolean","default":false}]},"default":{"_field":true}},{"name":"_o","type":{"type":"array","items":"boolean"},"default":[]},{"name":"_p","type":{"type":"array","items":"int"},"default":[0,0,0,0,0]},{"name":"_p_alt","type":{"type":"array","items":{"type":"record","name":"Bar","fields":[{"name":"_field","type":"Bar"}
]}}},{"name":"_q","type":{"type":"map","values":"string"},"default":{}},{"name":"_r","type":["null","double"],"default":null},{"name":"_s","type":{"type":"fixed","name":"duration","size":12,"logicalType":"duration"},"default":"\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000"},{"name":"_t","type":{"type":"fixed","name":"uuid","size":16,"logicalType":"uuid"},"default":"\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000"},{"name":"_u","type":{"type":"fixed","name":"u64","size":8},"default":"\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000"},{"name":"_v","type":{"type":"fixed","name":"u128","size":16},"default":"\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000"},{"name":"_w","type":{"type":"fixed","name":"i128","size":16},"default":"\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000"},{"name":"_x","type":"Bar"}]}"#
+ );
+}
+
+#[test]
+fn avro_rs_476_field_default_false() {
+ #[derive(AvroSchema)]
+ struct Bar {
+ _field: Box<Bar>,
+ }
+
+ #[derive(AvroSchema)]
+ #[avro(default = r#"{"_field": true}"#)]
+ struct Spam {
+ _field: bool,
+ }
+
+ #[derive(AvroSchema)]
+ struct Foo {
+ #[avro(default = false)]
+ _a: bool,
+ #[avro(default = false)]
+ _b: i8,
+ #[avro(default = false)]
+ _c: i16,
+ #[avro(default = false)]
+ _d: i32,
+ #[avro(default = false)]
+ _e: i64,
+ #[avro(default = false)]
+ _f: u8,
+ #[avro(default = false)]
+ _g: u16,
+ #[avro(default = false)]
+ _h: u32,
+ #[avro(default = false)]
+ _i: f32,
+ #[avro(default = false)]
+ _j: f64,
+ #[avro(default = false)]
+ _k: String,
+ #[avro(default = false)]
+ _l: Box<str>,
+ #[avro(default = false)]
+ _m: char,
+ #[avro(default = false)]
+ _n: Box<Spam>,
+ #[avro(default = false)]
+ _o: Vec<bool>,
+ #[avro(default = false)]
+ _p: [u8; 5],
+ #[avro(default = false)]
+ _p_alt: [Bar; 5],
+ #[avro(default = false)]
+ _q: HashMap<String, String>,
+ #[avro(default = false)]
+ _r: Option<f64>,
+ #[avro(default = false)]
+ _s: Duration,
+ #[avro(default = false)]
+ _t: Uuid,
+ #[avro(default = false)]
+ _u: u64,
+ #[avro(default = false)]
+ _v: u128,
+ #[avro(default = false)]
+ _w: i128,
+ #[avro(default = false)]
+ _x: Bar,
+ }
+
+ let schema = Foo::get_schema();
+ assert_eq!(
+ serde_json::to_string(&schema).unwrap(),
+
r#"{"type":"record","name":"Foo","fields":[{"name":"_a","type":"boolean"},{"name":"_b","type":"int"},{"name":"_c","type":"int"},{"name":"_d","type":"int"},{"name":"_e","type":"long"},{"name":"_f","type":"int"},{"name":"_g","type":"int"},{"name":"_h","type":"long"},{"name":"_i","type":"float"},{"name":"_j","type":"double"},{"name":"_k","type":"string"},{"name":"_l","type":"string"},{"name":"_m","type":"string"},{"name":"_n","type":{"type":"record","name":"Spam","fields":[{"name":"_field","type":"boolean","default":false}]}},{"name":"_o","type":{"type":"array","items":"boolean"}},{"name":"_p","type":{"type":"array","items":"int"}},{"name":"_p_alt","type":{"type":"array","items":{"type":"record","name":"Bar","fields":[{"name":"_field","type":"Bar"}]}}},{"name":"_q","type":{"type":"map","values":"string"}},{"name":"_r","type":["null","double"]},{"name":"_s","type":{"type":"fixed","name":"duration","size":12,"logicalType":"duration"}},{"name":"_t","type":{"type":"fixed","name":"u
uid","size":16,"logicalType":"uuid"}},{"name":"_u","type":{"type":"fixed","name":"u64","size":8}},{"name":"_v","type":{"type":"fixed","name":"u128","size":16}},{"name":"_w","type":{"type":"fixed","name":"i128","size":16}},{"name":"_x","type":"Bar"}]}"#
+ );
+}
+
+#[test]
+fn avro_rs_476_field_default_provided() {
+ #[derive(AvroSchema)]
+ #[avro(default = r#"{"_field": true}"#)]
+ struct Spam {
+ _field: bool,
+ }
+
+ #[derive(AvroSchema)]
+ struct Foo {
+ #[avro(default = "true")]
+ _a: bool,
+ #[avro(default = "42")]
+ _b: i8,
+ #[avro(default = "42")]
+ _c: i16,
+ #[avro(default = "42")]
+ _d: i32,
+ #[avro(default = "42")]
+ _e: i64,
+ #[avro(default = "42")]
+ _f: u8,
+ #[avro(default = "42")]
+ _g: u16,
+ #[avro(default = "42")]
+ _h: u32,
+ #[avro(default = "42.0")]
+ _i: f32,
+ #[avro(default = "42.0")]
+ _j: f64,
+ #[avro(default = r#""String""#)]
+ _k: String,
+ #[avro(default = r#""str""#)]
+ _l: Box<str>,
+ #[avro(default = r#""Z""#)]
+ _m: char,
+ #[avro(default = r#"{"_field": false}"#)]
+ _n: Box<Spam>,
+ #[avro(default = "[true, false, true]")]
+ _o: Vec<bool>,
+ #[avro(default = "[1,2,3,4,5]")]
+ _p: [u8; 5],
+ #[avro(
+ default = r#"[{"_field": true},{"_field": false},{"_field":
true},{"_field": false},{"_field": true}]"#
+ )]
+ _p_alt: [Spam; 5],
+ #[avro(default = r#"{"A": "B"}"#)]
+ _q: HashMap<String, String>,
+ #[avro(default = "42.0")]
Review Comment:
The default does not need to be a `null`, according to spec:
```
Default values for union fields correspond to the first schema that matches
in the union.
```
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