convert field value to string type
convert field value to string type

thinkjs/thinkjs,maxzhang/thinkjs,akira-cn/thinkjs,maxzhang/thinkjs,maxzhang/thinkjs,Qihoo360/thinkjs,snadn/thinkjs,akira-cn/thinkjs,75team/thinkjs,75team/thinkjs,akira-cn/thinkjs,75team/thinkjs