CODEWITHSUNDEEP
c++jsonargumentsrapidjson
J. Doe
J. Doe

Reputation: 107

C++ - Passing rapidjson::Document as an argument to a function

I'm passing pointer to rapidjson::Document as an argument.

foo(rapidjson::Document* jsonDocument)
{
    std::cout << jsonDocument["name"] << std::endl;
}

But I cannot do jsonDocument["name"] to access the name attribute.

Attempting to not use pointers leads to an error:

error: 'rapidjson::GenericDocument<Encoding, Allocator, StackAllocator>::GenericDocument(const rapidjson::GenericDocument<Encoding, Allocator, StackAllocator>&) [with Encoding = rapidjson::UTF8<>; Allocator = rapidjson::MemoryPoolAllocator<>; StackAllocator = rapidjson::CrtAllocator]' is private
GenericDocument(const GenericDocument&);

Can someone help me?

Upvotes: 4

Views: 4557

Answers (1)

Guillaume Racicot
Guillaume Racicot

Reputation: 41780

Use a reference or a value as argument. Using the [] with a pointer will try to use your document as if it was an array of document. A reference or a value will call the expected operator.

// a const reference
foo(const rapidjson::Document& jsonDocument) {
    std::cout << jsonDocument["name"] << std::endl;
}

// a copy (or move)
foo(rapidjson::Document jsonDocument) {
    std::cout << jsonDocument["name"] << std::endl;
}

I'd recommend you to use the reference, as your function don't need to consume any resources in the document, but only observe and print a value.

The call of this function will look like this:

rapidjson::Document doc = /* ... */;

foo(doc);

Upvotes: 5

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