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api/basic_json/json_serializer/index.md

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+# nlohmann::basic_json::json_serializer
+
+```
+template<typename T, typename SFINAE>
+using json_serializer = JSONSerializer<T, SFINAE>;
+```
+
+## Template parameters
+
+`T` : type to convert; will be used in the `to_json`/`from_json` functions
+
+`SFINAE` : type to add compile type checks via SFINAE; usually `void`
+
+## Notes
+
+#### Default type
+
+The default values for `json_serializer` is [`adl_serializer`](https://json.nlohmann.me/api/adl_serializer/index.md).
+
+## Examples
+
+Example
+
+The example below shows how a conversion of a non-default-constructible type is implemented via a specialization of the `adl_serializer`.
+
+```
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+namespace ns
+{
+// a simple struct to model a person (not default constructible)
+struct person
+{
+    person(std::string n, std::string a, int aa)
+        : name(std::move(n)), address(std::move(a)), age(aa)
+    {}
+
+    std::string name;
+    std::string address;
+    int age;
+};
+} // namespace ns
+
+namespace nlohmann
+{
+template <>
+struct adl_serializer<ns::person>
+{
+    static ns::person from_json(const json& j)
+    {
+        return {j.at("name"), j.at("address"), j.at("age")};
+    }
+
+    // Here's the catch! You must provide a to_json method! Otherwise, you
+    // will not be able to convert person to json, since you fully
+    // specialized adl_serializer on that type
+    static void to_json(json& j, ns::person p)
+    {
+        j["name"] = p.name;
+        j["address"] = p.address;
+        j["age"] = p.age;
+    }
+};
+} // namespace nlohmann
+
+int main()
+{
+    json j;
+    j["name"] = "Ned Flanders";
+    j["address"] = "744 Evergreen Terrace";
+    j["age"] = 60;
+
+    auto p = j.get<ns::person>();
+
+    std::cout << p.name << " (" << p.age << ") lives in " << p.address << std::endl;
+}
+```
+
+Output:
+
+```
+Ned Flanders (60) lives in 744 Evergreen Terrace
+```
+
+## Version history
+
+- Since version 2.0.0.