deploy: 4155e2938f

examples/basic_json_view__count.cpp

@@ -0,0 +1,31 @@
+#include <iostream>
+#include <nlohmann/json_view.hpp>
+
+using json_document = nlohmann::json_document;
+
+int main()
+{
+    // validate that every transaction of a batch carries exactly one
+    // "amount" field before materializing any of them into a nlohmann::json
+    // value -- count() counts every member with the key
+    json_document batch = json_document::parse(R"(
+      [
+        {"id": 1, "amount": 9.99},
+        {"id": 2},
+        {"id": 3, "amount": 5.00, "amount": 500.00}
+      ]
+    )");
+
+    const auto transactions = batch.root();
+    for (std::size_t i = 0; i < transactions.size(); ++i)
+    {
+        const auto transaction = transactions[i];
+        const auto amounts = transaction.count("amount");
+        if (amounts != 1)
+        {
+            std::cout << "transaction " << i << " has " << amounts << " \"amount\" fields\n";
+            continue;
+        }
+        std::cout << "transaction " << i << ": " << transaction["amount"].materialize().dump() << '\n';
+    }
+}