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Niels Lohmann
7b755737b4
From gregmarr's review of #5622: - count() counts every member with the key, so count(key) > 1 detects duplicate keys; it was contains() as 0/1 before. - get_to() passes types that get<T>() does not convert directly to from_json with the existing value, as basic_json::get_to() does, so that a from_json which sets only the fields present keeps the others. - array_index() checks the empty token and "-" first; the results are unchanged. - Docs: no "if an exception is thrown" where a view never changes anything; the borrowed source must also stay unmodified; items() on a temporary view is safe; back()/front() notes shortened; the basic_json see-also entries say how the view's results can differ. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
32 lines
993 B
C++
32 lines
993 B
C++
#include <iostream>
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#include <nlohmann/json_view.hpp>
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using json_document = nlohmann::json_document;
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int main()
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{
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// validate that every transaction of a batch carries exactly one
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// "amount" field before materializing any of them into a nlohmann::json
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// value -- count() counts every member with the key
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json_document batch = json_document::parse(R"(
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[
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{"id": 1, "amount": 9.99},
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{"id": 2},
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{"id": 3, "amount": 5.00, "amount": 500.00}
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]
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)");
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const auto transactions = batch.root();
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for (std::size_t i = 0; i < transactions.size(); ++i)
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{
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const auto transaction = transactions[i];
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const auto amounts = transaction.count("amount");
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if (amounts != 1)
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{
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std::cout << "transaction " << i << " has " << amounts << " \"amount\" fields\n";
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continue;
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}
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std::cout << "transaction " << i << ": " << transaction["amount"].materialize().dump() << '\n';
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}
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}
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