add key name to exception

[Furcube]

I use library to deserialize json to class.
Seem to be simple like this:

class test {
public:
  std::string str;
  int i;

  test(const json & json) :
          str(json.at("str").get<std::string>()),
          i(json.at("i"))) {
  }
};

But at will throw out_of_range without actually telling what it could not find. Makes deserialization without touching json.hpp much harder that it could be.

It would be good for exceptions to be more verbose.

Not sure that it will work in all cases, but it works for mine. I've changed json.hpp like this:

diff --git a/src/json.hpp b/src/json.hpp
index 9de73dd..a5d74b9 100644
--- a/src/json.hpp
+++ b/src/json.hpp
@@ -2686,7 +2686,11 @@ class basic_json
         // at only works for objects
         if (is_object())
         {
-            return m_value.object->at(key);
+               try {
+                       return m_value.object->at(key);
+               } catch(const std::out_of_range & e) {
+                       throw std::out_of_range("can't find \"" + key + '"');
+               }
         }
         else
         {
@@ -2724,7 +2728,11 @@ class basic_json
         // at only works for objects
         if (is_object())
         {
-            return m_value.object->at(key);
+               try {
+                       return m_value.object->at(key);
+               } catch(const std::out_of_range & e) {
+                       throw std::out_of_range("can't find \"" + key + '"');
+               }
         }
         else
         {

And now I can just log exception and tell what is missing.

[nlohmann]

Hi @Furcube, I changed the exceptions accordingly and also overworked the test suite and documentation. I hope you like it.