ℹ️ Read the blog post

Changes

• Fix support for NUL characters in deserializeJson()
• Make ElementProxy and MemberProxy non-copyable
• Change string copy policy: only string literal are stored by pointer
• JsonString is now stored by copy, unless specified otherwise
• Replace undocumented JsonString::Ownership with bool
• Rename undocumented JsonString::isLinked() to isStatic()
• Move public facing SFINAEs to template declarations

BREAKING CHANGES

In previous versions, MemberProxy (the class returned by operator[]) could lead to dangling pointers when used with a temporary string. To prevent this issue, MemberProxy and ElementProxy are now non-copyable.

Your code is likely to be affected if you use auto to store the result of operator[]. For example, the following line won't compile anymore:

auto value = doc["key"];

To fix the issue, you must append either .as<T>() or .to<T>(), depending on the situation.

For example, if you are extracting values from a JSON document, you should update like this:

- auto config = doc["config"];
+ auto config = doc["config"].as<JsonObject>();
const char* name = config["name"];

However, if you are building a JSON document, you should update like this:

- auto config = doc["config"];
+ auto config = doc["config"].to<JsonObject>();
config["name"] = "ArduinoJson";

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