3 files changed, 40 insertions, 17 deletions

diff --git a/src/core/common/VariantConverter.cpp b/src/core/common/VariantConverter.cpp
index 2d6d286..1f5f514 100644
--- a/src/core/common/VariantConverter.cpp
+++ b/src/core/common/VariantConverter.cpp
@@ -31,18 +31,20 @@
 
 namespace ousia {
 
-static std::string msgUnexpectedType(VariantType actualType,
+static std::string msgUnexpectedType(const Variant &v,
                                      VariantType requestedType)
 {
-	return std::string("Cannot convert ") + Variant::getTypeName(actualType) +
-	       std::string(" to ") + Variant::getTypeName(requestedType);
+	return std::string("Cannot convert ") + v.getTypeName() + std::string(" ") +
+	       VariantWriter::writeJsonToString(v, false) + std::string(" to ") +
+	       Variant::getTypeName(requestedType);
 }
 
 static std::string msgImplicitConversion(VariantType actualType,
-                                     VariantType requestedType)
+                                         VariantType requestedType)
 {
-	return std::string("Implicit conversion from ") + Variant::getTypeName(actualType) +
-	       std::string(" to ") + Variant::getTypeName(requestedType);
+	return std::string("Implicit conversion from ") +
+	       Variant::getTypeName(actualType) + std::string(" to ") +
+	       Variant::getTypeName(requestedType);
 }
 
 bool VariantConverter::toBool(Variant &var, Logger &logger, Mode mode)
@@ -76,7 +78,7 @@ bool VariantConverter::toBool(Variant &var, Logger &logger, Mode mode)
 	}
 
 	// No conversion possible, assign default value and log error
-	logger.error(msgUnexpectedType(var.getType(), VariantType::BOOL));
+	logger.error(msgUnexpectedType(var, VariantType::BOOL));
 	var = false;
 	return false;
 }
@@ -132,7 +134,7 @@ bool VariantConverter::toInt(Variant &var, Logger &logger, Mode mode)
 	}
 
 	// No conversion possible, assign default value and log error
-	logger.error(msgUnexpectedType(var.getType(), VariantType::INT));
+	logger.error(msgUnexpectedType(var, VariantType::INT));
 	var = 0;
 	return false;
 }
@@ -186,7 +188,7 @@ bool VariantConverter::toDouble(Variant &var, Logger &logger, Mode mode)
 	}
 
 	// No conversion possible, assign default value and log error
-	logger.error(msgUnexpectedType(var.getType(), VariantType::DOUBLE));
+	logger.error(msgUnexpectedType(var, VariantType::DOUBLE));
 	var = 0.0;
 	return false;
 }
@@ -260,7 +262,7 @@ bool VariantConverter::toString(Variant &var, Logger &logger, Mode mode)
 	}
 
 	// No conversion possible, assign default value and log error
-	logger.error(msgUnexpectedType(var.getType(), VariantType::STRING));
+	logger.error(msgUnexpectedType(var, VariantType::STRING));
 	var = "";
 	return false;
 }
@@ -296,7 +298,7 @@ bool VariantConverter::toArray(Variant &var, const RttiType &innerType,
 	}
 
 	// No conversion possible, assign the default value and log an error
-	logger.error(msgUnexpectedType(var.getType(), VariantType::ARRAY));
+	logger.error(msgUnexpectedType(var, VariantType::ARRAY));
 	var.setArray(Variant::arrayType{});
 	return false;
 }
@@ -327,7 +329,7 @@ bool VariantConverter::toMap(Variant &var, const RttiType &innerType,
 	}
 
 	// No conversion possible, assign the default value and log an error
-	logger.error(msgUnexpectedType(var.getType(), VariantType::MAP));
+	logger.error(msgUnexpectedType(var, VariantType::MAP));
 	var.setMap(Variant::mapType{});
 	return false;
 }
@@ -339,7 +341,7 @@ bool VariantConverter::toFunction(Variant &var, Logger &logger)
 	}
 
 	// No conversion possible, assign the default value and log an error
-	logger.error(msgUnexpectedType(var.getType(), VariantType::MAP));
+	logger.error(msgUnexpectedType(var, VariantType::MAP));
 	var.setFunction(std::shared_ptr<Function>{new Method<void>([](
 	    const Variant::arrayType &args, void *thisRef) { return Variant{}; })});
 	return false;
@@ -356,8 +358,7 @@ bool VariantConverter::convert(Variant &var, const RttiType &type,
 	} else if (&type == &RttiTypes::Nullptr) {
 		// Make sure the variant is set to null
 		if (!var.isNull()) {
-			logger.error(
-			    msgUnexpectedType(var.getType(), VariantType::NULLPTR));
+			logger.error(msgUnexpectedType(var, VariantType::NULLPTR));
 			var.setNull();
 			return false;
 		}
@@ -381,7 +382,7 @@ bool VariantConverter::convert(Variant &var, const RttiType &type,
 	// If none of the above primitive types is requested, we were
 	// obviously asked for a managed object.
 	if (!var.isObject()) {
-		logger.error(msgUnexpectedType(var.getType(), VariantType::OBJECT));
+		logger.error(msgUnexpectedType(var, VariantType::OBJECT));
 		var.setNull();
 		return false;
 	}
diff --git a/src/core/common/VariantWriter.cpp b/src/core/common/VariantWriter.cpp
index 713ec01..fc23359 100644
--- a/src/core/common/VariantWriter.cpp
+++ b/src/core/common/VariantWriter.cpp
@@ -16,6 +16,8 @@
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+#include <sstream>
+
 #include "Variant.hpp"
 #include "VariantWriter.hpp"
 
@@ -161,5 +163,14 @@ void VariantWriter::writeJson(const Variant &var, std::ostream &stream,
 {
 	writeJsonInternal(var, stream, pretty, 0);
 }
+
+std::string VariantWriter::writeJsonToString(const Variant &var, bool pretty)
+{
+	std::stringstream ss;
+	writeJson(var, ss, pretty);
+	return ss.str();
+}
+
+
 }
 
diff --git a/src/core/common/VariantWriter.hpp b/src/core/common/VariantWriter.hpp
index 211da34..7fe32fb 100644
--- a/src/core/common/VariantWriter.hpp
+++ b/src/core/common/VariantWriter.hpp
@@ -28,6 +28,7 @@
 #ifndef _OUSIA_VARIANT_WRITER_HPP_
 #define _OUSIA_VARIANT_WRITER_HPP_
 
+#include <string>
 #include <ostream>
 
 namespace ousia {
@@ -42,7 +43,8 @@ class Variant;
 class VariantWriter {
 public:
 	/**
-	 * Dumps the Variant as JSON data.
+	 * Dumps the Variant as JSON data. Note that the resulting JSON data is
+	 * invalid if the Variant consists of function or object references.
 	 *
 	 * @param var is the variant that should be serialized.
 	 * @param stream is the stream the result should be written to.
@@ -50,6 +52,15 @@ public:
 	 */
 	static void writeJson(const Variant &var, std::ostream &stream,
 	                      bool pretty = true);
+
+	/**
+	 * Dumps the Variant as JSON data to a string.
+	 *
+	 * @param var is the variant that should be serialized.
+	 * @param pretty if true, the resulting value is properly indented.
+	 */
+	static std::string writeJsonToString(const Variant &var, bool pretty = true);
+
 };
 }