Schema validation with subschema and internal reference

[nicomuns]

Hello,

I'm having trouble validating a JSON against a JSON schema. My case is a bit specific, I'll try to describe it as clearly as possible.

I have a function that takes two string arguments:

• p_rootSchemaPath: the path of the root schema
• p_location: a location inside the root schema, in the form /key1/key2/..., used to extract a specific part of the root schema (It is empty most of the time).

I create my validator with make_json_schema and give it my own URI resolver to resolve external references and it works fine.

Now my case is the following, p_rootSchemaPath can also be a JSON which is not a schema. But then p_location is not empty, it is used to extract a part of p_rootSchemaPath, part which contains an internal reference pointing to an actual schema defined somewhere else in the document, like so "$ref": "#/.../...".

The code looks like this:

void func(const std::string& p_rootSchemaPath, const std::string& p_location) { ojson schema = ojson::parse(retrieveSchemaContent(p_rootSchemaPath)); if (p_location != "") { ojson schemaPart = jsonpointer::get(schema, p_location); schema = schemaPart; } auto resolver = [](const uri& p_uri) { // ... }; jsonschema::evaluation_options options; evalOptions.default_base_uri(p_rootSchemaPath); validator = std::make_unique<jsonschema::json_schema<ojson>>(jsonschema::make_json_schema(schema, resolver, options)); } 

And this is what a simplified root schema looks like here (which again is not a schema in this particular case):

{ "key_A": { "key_A_1": { "foo": { "payload": { "type": "object", "patternProperties": { "some_regex": { "type": "object", "$ref": "#/key_A/key_A_2/bar" } } } } }, "key_A_2": { "bar": { "$schema": "http://json-schema.org/draft-07/schema#", "type": "object", "properties": { "name": { "type": "string" }, "containers": { "type": "array", "items": [ { "type": "object", "properties": { "number_A": { "type": "number" }, "number_B": { "type": "number" } } } ] } } } } } } 

With p_location = "/key_A/key_A_1/foo/payload"

So in my function, after the if block, I end up with schema being equal to:

{ "type": "object", "patternProperties": { "some_regex": { "type": "object", "$ref": "#/key_A/key_A_2/bar" } } } 

But then I don't know how to proceed. The URI resolver does not get called for the internal reference (which I think is normal because it is only called for external references?).

I get the error Unresolved reference 'path_of_root_schema.json#/key_A/key_A_2/bar' when calling make_json_schema.
In this error message, path_of_root_schema.json does not have the same value as p_rootSchemaPath.
If p_rootSchemaPath = "/this/is/my/folder/file.json", the error says Unresolved reference 'is/my/folder/file.json#/key_A/key_A_2/bar'.

I tried simplify my use case the most I could to avoid making an even longer post. Let me know if some information is missing.

Thanks in advance!

[danielaparker]

Okay, from jsoncons's point of view, $ref in payload is accessing an external resource (one outside a schema resource.) Therefore, I think you should substitute

"$ref": "/key_A/key_A_2/bar" 

for

"$ref": "#/key_A/key_A_2/bar" 

Note that we write the reference with a leading slash to prevent URI resolution from merging '/key_A/key_A_2/bar' with the default base URI path '/this/is/my/folder/file' (which we don't want.)

Then all references should be resolved in the usual way:

#include <jsoncons/json.hpp> #include <jsoncons_ext/jsonschema/jsonschema.hpp> #include <jsoncons_ext/jsonpointer/jsonpointer.hpp> #include <iostream> namespace jsonschema = jsoncons::jsonschema; namespace jsonpointer = jsoncons::jsonpointer; std::string input_str = R"( {  "key_A": {  "key_A_1": {  "foo": {  "payload": {  "type": "object",  "patternProperties": {  "some_regex": {  "type": "object",  "$ref": "/key_A/key_A_2/bar"   }  }  }  }  },  "key_A_2": {  "bar": {  "$schema": "http://json-schema.org/draft-07/schema#",  "type": "object",  "properties": {  "name": { "type": "string" },  "containers": {  "type": "array",  "items": [  {  "type": "object",  "properties": {  "number_A": { "type": "number" },  "number_B": { "type": "number" }  }  }  ]  }  }  }  }  } } )"; int main() { auto input = jsoncons::ojson::parse(input_str); auto schema = jsonpointer::get(input, "/key_A/key_A_1/foo/payload"); auto resolver = [&](const jsoncons::uri& uri) -> jsoncons::ojson { std::cout << "path: " << uri.path() << "\n"; std::error_code ec; jsoncons::ojson schemaPart = jsonpointer::get(input, uri.path(), ec); return ec ? jsoncons::ojson::null() : schemaPart; }; try { auto options = jsonschema::evaluation_options{} .default_base_uri("/this/is/my/folder/file"); auto compiled = jsonschema::make_json_schema(schema, resolver, options); } catch (const std::exception& e) { std::cout << e.what() << "\n"; } }

Output:

path: /key_A/key_A_2/bar 

[nicomuns]

Thanks a lot, it is working now.
I left the # in the schema but removed it when loading the schema content in RAM.