deploy: 4155e2938f

examples/basic_json_view__contains.cpp

@@ -0,0 +1,30 @@
+#include <iostream>
+#include <nlohmann/json_view.hpp>
+
+using json_document = nlohmann::json_document;
+
+int main()
+{
+    // count how many of many incoming records carry an optional "retry_of"
+    // field -- contains() only walks the flat index, so scanning a large
+    // batch like this never builds a single nlohmann::json value
+    json_document batch = json_document::parse(R"(
+      [
+        {"id": 1},
+        {"id": 2, "retry_of": 1},
+        {"id": 3},
+        {"id": 4, "retry_of": 3}
+      ]
+    )");
+
+    const auto records = batch.root();
+    std::size_t retries = 0;
+    for (std::size_t i = 0; i < records.size(); ++i)
+    {
+        if (records[i].contains("retry_of"))
+        {
+            ++retries;
+        }
+    }
+    std::cout << retries << " of " << records.size() << " records are retries\n";
+}