我是Groovy和Grails的新手，我正在尝试创建一个返回JSON格式字符串的方法。
我读了一些关于转换器的内容，以及我从几个来源（here和here可以理解的内容）我应该能够做到这一点：
import grails.converters.JSON
class Record {
//...
private Map _metadata = [:]
String getMetadataJSON(){
return render _metadata as JSON
}
}
不仅这不起作用，而且＃34;渲染＆＃34;关键字尚未解析。
所以我的两个问题是：
答案 0 :(得分：3)
##
## Auto Generated makefile by CodeLite IDE
## any manual changes will be erased
##
## Debug
ProjectName :=AreaComp
ConfigurationName :=Debug
WorkspacePath := "/Users/tuckerfowler/Documents/CS3304"
ProjectPath := "/Users/tuckerfowler/Documents/CS3304 /AreaComp"
IntermediateDirectory :=./Debug
OutDir := $(IntermediateDirectory)
CurrentFileName :=
CurrentFilePath :=
CurrentFileFullPath :=
User :=Tucker Fowler
Date :=18/01/2016
CodeLitePath :="/Users/tuckerfowler/Library/Application Support/codelite"
LinkerName :=/usr/bin/g++
SharedObjectLinkerName :=/usr/bin/g++ -dynamiclib -fPIC
ObjectSuffix :=.o
DependSuffix :=.o.d
PreprocessSuffix :=.i
DebugSwitch :=-g
IncludeSwitch :=-I
LibrarySwitch :=-l
OutputSwitch :=-o
LibraryPathSwitch :=-L
PreprocessorSwitch :=-D
SourceSwitch :=-c
OutputFile :=$(IntermediateDirectory)/$(ProjectName)
Preprocessors :=
ObjectSwitch :=-o
ArchiveOutputSwitch :=
PreprocessOnlySwitch :=-E
ObjectsFileList :="AreaComp.txt"
PCHCompileFlags :=
MakeDirCommand :=mkdir -p
LinkOptions :=
IncludePath := $(IncludeSwitch). $(IncludeSwitch).
IncludePCH :=
RcIncludePath :=
Libs :=
ArLibs :=
LibPath := $(LibraryPathSwitch).
##
## Common variables
## AR, CXX, CC, AS, CXXFLAGS and CFLAGS can be overriden using an environment variables
##
AR := /usr/bin/ar rcu
CXX := /usr/bin/g++
CC := /usr/bin/gcc
CXXFLAGS := -g -O0 -Wall $(Preprocessors)
CFLAGS := -g -O0 -Wall $(Preprocessors)
ASFLAGS :=
AS := /usr/bin/as
##
## User defined environment variables
##
CodeLiteDir:=/Users/tuckerfowler/Downloads/codelite.app/Contents/SharedSupport/
Objects0=$(IntermediateDirectory)/main.cpp$(ObjectSuffix)
Objects=$(Objects0)
##
## Main Build Targets
##
.PHONY: all clean PreBuild PrePreBuild PostBuild MakeIntermediateDirs
all: $(OutputFile)
$(OutputFile): $(IntermediateDirectory)/.d
$(Objects)
@$(MakeDirCommand) $(@D)@echo "" > $(IntermediateDirectory)/.d
@echo $(Objects0) > $(ObjectsFileList)
$(LinkerName)
$(OutputSwitch)
$(OutputFile)
@$(ObjectsFileList)
$(LibPath)
$(Libs)
$(LinkOptions)
MakeIntermediateDirs:
@test -d ./Debug || $(MakeDirCommand) ./Debug
$(IntermediateDirectory)/.d:
@test -d ./Debug || $(MakeDirCommand) ./Debug
PreBuild:
##
## Objects
##
$(IntermediateDirectory)/main.cpp
$(ObjectSuffix):main.cpp
$(IntermediateDirectory)/main.cpp
$(DependSuffix)
$(CXX)
$(IncludePCH)
$(SourceSwitch) "/Users/tuckerfowler/Documents/CS3304/AreaComp/main.cpp"
$(CXXFLAGS)
$(ObjectSwitch)
$(IntermediateDirectory)/main.cpp
$(ObjectSuffix)
$(IncludePath)
$(IntermediateDirectory)/main.cpp
$(DependSuffix): main.cpp
@$(CXX)
$(CXXFLAGS)
$(IncludePCH)
$(IncludePath)-MG-MP-MT
$(IntermediateDirectory)/main.cpp
$(ObjectSuffix) -MF
$(IntermediateDirectory)/main.cpp
$(DependSuffix) -MM "main.cpp"
$(IntermediateDirectory)/main.cpp
$(PreprocessSuffix): main.cpp
@$(CXX)
$(CXXFLAGS)
$(IncludePCH)
$(IncludePath)
$(PreprocessOnlySwitch)
$(OutputSwitch)
$(IntermediateDirectory)/main.cpp
$(PreprocessSuffix) "main.cpp"
-include $(IntermediateDirectory)/*$(DependSuffix)
##
## Clean
##
clean:
$(RM) -r ./Debug/
用于Grails中的Controller，而不是（看起来像是）Domain Class（在您的示例中）。如果你想获得某些东西的JSON表示，那么只需：
render以上内容将以String getMetadataJSON() {
(_metadata as JSON)
}
格式返回String个代表。 Groovy不需要JSON关键字。