Replace ValidationError::schema with custom errors

[zhiburt]

Hi there, bump into here via hacktoberfest mark.

Honestly most likely it doesn't address JSONPointer correctly in errors.
And I was not sure which type of error better use for things like as64 error or regex syntax error but I did used ValidationError::format.

Note: there might be an issue with cargo fmt.

closes #235

Thank you for the library.

[Stranger6667]

Thank you @zhiburt !

I am happy to see your contribution :) I'll try to review this in the next few days :) Could you, please:

• Run cargo fmt
• Remove the unused function
• Add a changelog entry

[Stranger6667]

Honestly most likely it doesn't address JSONPointer correctly in errors.

I think it is alright, in any case, it is an improvement over the status quo

And I was not sure which type of error better use for things like as64 error or regex syntax error but I did used

That's alright :)

[codecov]

Codecov Report

Merging #280 (63c99d3) into master (3b57866) will decrease coverage by 2.64%.
The diff coverage is 9.05%.

@@            Coverage Diff             @@
##           master     #280      +/-   ##
==========================================
- Coverage   83.15%   80.50%   -2.65%     
==========================================
  Files          56       56              
  Lines        5124     5336     +212     
==========================================
+ Hits         4261     4296      +35     
- Misses        863     1040     +177     

Impacted Files	Coverage Δ
jsonschema/src/compilation/mod.rs	85.92% <0.00%> (-6.08%)	⬇️
jsonschema/src/error.rs	62.56% <ø> (+0.13%)	⬆️
jsonschema/src/keywords/additional_items.rs	77.92% <0.00%> (-7.80%)	⬇️
jsonschema/src/keywords/all_of.rs	80.39% <0.00%> (-6.85%)	⬇️
jsonschema/src/keywords/any_of.rs	84.78% <0.00%> (-8.08%)	⬇️
jsonschema/src/keywords/content.rs	75.00% <0.00%> (-6.46%)	⬇️
jsonschema/src/keywords/dependencies.rs	77.77% <0.00%> (-12.47%)	⬇️
jsonschema/src/keywords/enum_.rs	72.30% <0.00%> (-4.75%)	⬇️
jsonschema/src/keywords/exclusive_maximum.rs	81.69% <0.00%> (-4.88%)	⬇️
jsonschema/src/keywords/exclusive_minimum.rs	77.46% <0.00%> (-4.63%)	⬇️
... and 42 more

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[Stranger6667]

During the compilation phase, schema_path means a path within the JSON Schema meta schemas, and instance_path is a path within the input schema. Given that, the schema_path argument to ValidationError constructors can't be easily derived, so we can leave it empty - this is a corner case anyway (something that metaschema validation doesn't catch).

So, we need to put pointers constructed from context to instance_path argument and JSONPointer::default() to the schema_path one. As far as I see, it is the other way around now.

[zhiburt]

During the compilation phase, schema_path means a path within the JSON Schema meta schemas

So its essentially pointers to this map?

https://github.com/Stranger6667/jsonschema-rs/blob/aaadd99b2cc376d9018759ecedbbe68c0700d2ab/jsonschema/src/compilation/options.rs#L28-L74

I am curious if we could reuse self.schema_path in structures like this as schema_path arg in error.

https://github.com/Stranger6667/jsonschema-rs/blob/fba763fd4fed01ae8073c6a0c9204cb8c7080933/jsonschema/src/keywords/pattern.rs#L19-L23

[Stranger6667]

So its essentially pointers to this map?

Yep, I'd say that they point to some locations within the values of this map.

I am curious if we could reuse self.schema_path in structures like this as schema_path arg in error.

In the majority of the cases, these schema_path values are already used by the meta-schema validators. If the meta-schema is not capable to catch the bug, then these manual error-handling scenarios should catch the problem.

Of course, we may try to keep the meta-schema context manually and trace all the paths during the compilation. However, it will be hard to do as we'll need to do it differently for different JSON Schema drafts, so I assume it will be easier to tweak the meta-schema instead - it happened before and was caused by an actual bug in meta schemas.

Hope I helps :)

[zhiburt]

I am curious if we could reuse self.schema_path in structures like this as schema_path arg in error.

In the majority of the cases, these schema_path values are already used by the meta-schema validators. If the meta-schema is not capable to catch the bug, then these manual error-handling scenarios should catch the problem.

I guess I did make a typo.
I meant to say maybe we could use this self.schema_path in errors.
Like this

ValidationError::format(self.schema_path, context.clone().into_pointer(), ...)

[Stranger6667]

I meant to say maybe we could use this self.schema_path in errors.

These structures are available only after compilation, the compilation process creates a tree of them. We already use meta-schema validators during the compilation process - errors from it will have exactly these schema_path values.

[Stranger6667]

Added a few comments - most of them are quite similar to each other and mostly are about choosing the proper ValidationError variant

[zhiburt]

You've spend quite a bit of time reviewing it.

[Stranger6667]

Thanks! I think we're getting closer to merging :) A couple of minor things

[Stranger6667]

Awesome! Thanks :)