how to make the rapidjson::SchemaValidator variable in the class

Question

I have an class it is going to validate the json data with json schema

const char *ptr = R"(
    {
    "type":"object",
    "properties":{
    "name":{"type":"string"}
    },
    "required":["name"]
    }
    )";
const char *data = R"(
    {
    "name":"12"
    }
    )";
class Test {
   public:
    bool validate(Document &doc) {
        Document sdoc;
        sdoc.Parse(ptr);
        RAPIDJSON_ASSERT(!sdoc.HasParseError());
        SchemaDocument schema(sdoc);
        SchemaValidator validator(schema);
        if (doc.Accept(validator))
            return true;
        else
            return false;
    }
};

this code was working properly but in my requirement I no need to create the validator again and again when ever it is required,I feel if the validator is inside the class member then we can reduce the time

class Test {
    SchemaValidator validator;

   public:
    bool validate(Document &doc) {
        if (doc.Accept(validator))
            return true;
        else
            return false;
    }
};

can anybody please help how we can do for my requirement.

Answer 1

You need to hold both rapidjson::SchemaDocument and rapidjson::SchemaValidator as your member fields, because SchemaValidator keeps non-owning pointer to SchemaDocument. Sth like this:

class Test2 {
public:
    Test2()
        : _schema{[]() {
            rapidjson::Document sdoc;
            sdoc.Parse(ptr);
            if (sdoc.HasParseError()) {
                throw std::runtime_error("Bad schema");
            }
            return rapidjson::SchemaDocument(sdoc);
        }()}
        , _validator{_schema} {}
    bool validate(rapidjson::Document &doc) {
        if (doc.Accept(_validator))
            return true;
        else
            return false;
    }

private:
    rapidjson::SchemaDocument _schema;
    rapidjson::SchemaValidator _validator;
};

Then to be cleaner, you can make your class to accept std::string schema in the constructor

    Test2(std::string schema)
        : _schema{[schema]() {
            rapidjson::Document sdoc;
            sdoc.Parse(schema.c_str());
            if (sdoc.HasParseError()) {
                throw std::runtime_error("Bad schema");
            }
            return rapidjson::SchemaDocument(sdoc);
        }()}
        , _validator{_schema} {}