#20 asString() of intValue throws exception

[sorenriise]

I had expected just about everything should be able to retrieve as String -- including objects and arrays (feature suggestion).

reader.parse("{\"intvalue\":1}",root);
if (root["intvalue"].isConvertibleTo(Json::stringValue)) // isConvertibleTo is returning true
cout << root["intvalue"].asString() // throws exception......

[Anonymous]

I ran into this bug as well. If "isConvertibleTo" return true, I expected asX() to work, but it does not for int/uint/real.

Here is a simple patch to fix it:

diff -r 3f652b479082 jsoncpp/src/lib_json/json_value.cpp
--- a/jsoncpp/src/lib_json/json_value.cpp Wed Sep 15 11:16:11 2010 -0400
+++ b/jsoncpp/src/lib_json/json_value.cpp Thu Sep 16 12:08:41 2010 -0400
@@ -8,7 +8,9 @@
#ifdef JSON_USE_CPPTL
# include <cpptl/conststring.h>
#endif
+#include <iosfwd>
+#include <sstream> // size_t
#ifndef JSON_USE_SIMPLE_INTERNAL_ALLOCATOR
# include "json_batchallocator.h"
#endif // #ifndef JSON_USE_SIMPLE_INTERNAL_ALLOCATOR
@@ -716,6 +718,11 @@
case intValue:
case uintValue:
case realValue:
+ {
+ std::ostringstream os;
+ os << ((type_ == intValue) ? value_.int_ : (type_ == uintValue) ? value_.uint_ : value_.real_);
+ return os.str();
+ }
case arrayValue:
case objectValue:
JSON_ASSERT_MESSAGE( false, "Type is not convertible to string" );

[Sergey Kolomenkin]

Following code is not correct:

> os << ((type_ == intValue) ? value_.int_ : (type_ == uintValue) ?
value_.uint_ : value_.real_);

C++ will try to cast the whole expression "((type_ == intValue) ? value_.int_ : (type_ == uintValue) ?
value_.uint_ : value_.real_)" to one type (double will be used I think).
So int and uint will be converted to double. Perhaps it may loose data on converting uint to double.
It is better to use smth. like "if(type_ == intValue) os << value_.int_; else ..."

[Christopher Dunn]

Objects and arrays are serializable to strings, but not strictly convertible. Maybe it's an unfair distinction, but since serialization has so many special cases, we're stuck with this for now.