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### jsoncons::jsonschema::json_schema<Json>::validate
```cpp
void validate(const Json& instance) const; (1)
void validate(const Json& instance, Json& patch) const; (2)
template <typename MsgReporter>
void validate(const Json& instance, const MsgReporter& reporter) const; (3)
template <typename MsgReporter>
void validate(const Json& instance, const MsgReporter& reporter, Json& patch) const; (4)
void validate(const Json& instance, json_visitor<Json>& visitor) const; (5)
```
(1) Validates input JSON against a JSON Schema with a default error reporter
that throws upon the first schema violation.
(2) Validates input JSON against a JSON Schema with a default error reporter
that throws upon the first schema violation. Writes a JSONPatch document to the output
parameter.
(3) Validates input JSON against a JSON Schema with a provided error reporter
that is called for each schema violation.
(4) Validates input JSON against a JSON Schema with a provided error reporter
that is called for each schema violation. Writes a JSONPatch document to the output
parameter.
(5) Validates input JSON against a JSON Schema and writes the validation messages
to a [json_visitor](../../corelib/basic_json_visitor.md).
#### Parameters
<table>
<tr>
<td>instance</td>
<td>Input Json</td>
</tr>
<tr>
<td>reporter</td>
<td>A function object with signature equivalent to
<pre>
<a href="../walk_result.md">walk_result</a> fun(const <a href="../validation_message.md">validation_message</a>& msg);</pre>
</td>
</tr>
<tr>
<td>patch</td>
<td>A JSONPatch document that may be applied to the input JSON
to fill in missing properties that have "default" values in the
schema.</td>
</tr>
<tr>
<td>visitor</td>
<td>A [json_visitor](../../corelib/basic_json_visitor.md) that receives JSON events
corresponding to an array of validation messages.</td>
</tr>
</table>
#### Return value
None.
#### Exceptions
(1) - (2) Throws a [validation_error](../validation_error.md) for the first schema violation.
### Examples
```cpp
#include <jsoncons/json.hpp>
#include <jsoncons_ext/jsonschema/jsonschema.hpp>
#include <iostream>
using jsoncons::ojson;
namespace jsonschema = jsoncons::jsonschema;
int main()
std::string schema_str = R"(
{
"$id": "https://example.com/arrays.schema.json",
"$schema": "https://json-schema.org/draft/2020-12/schema",
"description": "A representation of a person, company, organization, or place",
"type": "object",
"properties": {
"fruits": {
"type": "array",
"items": {
"type": "string"
}
},
"vegetables": {
"type": "array",
"items": { "$ref": "#/$defs/veggie" }
}
},
"$defs": {
"veggie": {
"type": "object",
"required": [ "veggieName", "veggieLike" ],
"properties": {
"veggieName": {
"type": "string",
"description": "The name of the vegetable."
},
"veggieLike": {
"type": "boolean",
"description": "Do I like this vegetable?"
}
}
}
}
}
)";
std::string data_str = R"(
{
"fruits": [ "apple", "orange", "pear" ],
"vegetables": [
{
"veggieName": "potato",
"veggieLike": true
},
{
"veggieName": "broccoli",
"veggieLike": "false"
},
{
"veggieName": "carrot",
"veggieLike": false
},
{
"veggieName": "Swiss Chard"
}
]
}
)";
ojson schema = ojson::parse(schema_str);
jsonschema::json_schema<ojson> compiled = jsonschema::make_json_schema(std::move(schema));
ojson data = ojson::parse(data_str);
std::cout << "\n(1) Validate using exceptions\n";
try
{
compiled.validate(data);
}
catch (const std::exception& e)
{
std::cout << e.what() << "\n";
}
std::cout << "\n(2) Validate using reporter callback\n";
auto reporter = [](const jsonschema::validation_message& msg) -> jsonschema::walk_result
{
std::cout << message.instance_location().string() << ": " << message.message() << "\n";
return walk_result::advance;
};
compiled.validate(data, reporter);
std::cout << "\n(3) Validate outputting to a json decoder\n";
jsoncons::json_decoder<ojson> decoder;
compiled.validate(data, decoder);
ojson output = decoder.get_result();
std::cout << pretty_print(output) << "\n";
}
```
Output:
```
(1) Validate using exceptions
/vegetables/1/veggieLike: Expected boolean, found string
(2) Validate using reporter callback
/vegetables/1/veggieLike: Expected boolean, found string
/vegetables/3: Required property 'veggieLike' not found.
(3) Validate outputting to a json decoder
[
{
"valid": false,
"evaluationPath": "/properties/vegetables/items/$ref/properties/veggieLike/type",
"schemaLocation": "https://example.com/arrays.schema.json#/$defs/veggie/properties/veggieLike",
"instanceLocation": "/vegetables/1/veggieLike",
"error": "Expected boolean, found string"
},
{
"valid": false,
"evaluationPath": "/properties/vegetables/items/$ref/required",
"schemaLocation": "https://example.com/arrays.schema.json#/$defs/veggie/required",
"instanceLocation": "/vegetables/3",
"error": "Required property 'veggieLike' not found."
}
]
```
|
