chupaty opened a new issue, #64:
URL: https://github.com/apache/avro-rs/issues/64
The specification states the following:
> A schema or protocol may not contain multiple definitions of a fullname.
Further, a name must be defined before it is used (“before” in the
depth-first, left-to-right traversal of the JSON parse tree, where the types
attribute of a protocol is always deemed > to come “before” the messages
attribute.)
This means that the following schema is valid (the A type is defined in
b_field_one and the type is not defined with b_field_two):
```
{
"name":"B",
"type":"record",
"fields":[
{
"name":"b_field_one",
"type":{"name":"A","type":"record","fields":[]}
},
{
"name":"b_field_two",
"type":{"name":"A"}
},
]
}
```
This crate makes it easy to load a schemata in the form of a sequence
(Schema::parse_list) of schema where:
- The ordering rule is relaxed (no need to load the schemata in a particular
order)
- The defined-once rule is applied to the whole sequence, instead of per
schema
However I can't find a way to output an individual schema in a schemata that
is 'complete' (ie does not depend on other schemas, and otherwise complies with
the rules). For example:
```
let schema_str_1 = r#"{
"name": "A",
"doc": "A's schema",
"type": "record",
"fields": [
]
}"#;
let schema_str_2 = r#"{
"name": "B",
"doc": "B's schema",
"type": "record",
"fields": [
{"name": "b_field_one", "type": "A"},
{"name": "b_field_two", "type": "A"}
]
}"#;
let schema_strs = [schema_str_1, schema_str_2];
let schemata = Schema::parse_list(&schema_strs)?;
for d in schemata {
println!("{}",d.canonical_form());
}
```
Gives the following canonical schemas (for A I think this is OK, B is
problematic as there is no definition for A):
```
{"name":"A","type":"record","fields":[]}
{"name":"B","type":"record","fields":[{"name":"b_field_one","type":"A"},{"name":"b_field_two","type":"A"}]}
```
I believe the canonical form for B should actually be:
```
{"name":"B","type":"record","fields":[{"name":"b_field_one","type":{"name":"A","type":"record","fields":[]}},{"name":"b_field_two","type":"A"}]}
```
Do we have a way of producing this 'correct' form? This is necessary for
fingerprint calculation and some schema registry interactions.
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