标签：
restfull路由如下：
router.get(‘/:id‘, controller.show);
mongoes代码如下：
exports.show = function(req, res) { Notice.findById(req.params.id, function (err, notice) { if(err) { res.json({no:0,msg:‘获取失败:‘+err}); }else{ var result = {no:1}; result.obj=notice; res.json(result); } }); };
客户端访问：
http://192.168.0.165:9000/api/notices/11
打印结果如下;
{ "no": 0, "msg": "获取失败:CastError: Cast to ObjectId failed for value \"11\" at path \"_id\"" }
具体原因参考：
http://stackoverflow.com/questions/14940660/whats-mongoose-error-cast-to-objectid-failed-for-value-xxx-at-path-id
Mongoose‘s findById method casts the id parameter to the type of the model‘s _id field so that it can properly query for the matching doc. This is an ObjectId but "11" is not a valid ObjectId so the cast fails.
如果客户端传递的是mongo ObjectId就不会报以上错误．例如以下访问方式：
http://192.168.0.165:9000/api/notices/41224d776a326fb40f000001 就不会报错．
{ "no": 1, "obj": null }
在正常情况下，客户端传递的id参数是从后台获取的ObjectId,但是为了严谨性现在做以下处理：
exports.show = function(req, res) { var id = req.params.id; if (id.match(/^[0-9a-fA-F]{24}$/)) { Notice.findById(id, function (err, notice) { if(err) { res.json({no:0,msg:‘获取失败:‘+err}); }else{ var result = {no:1}; result.obj=notice; res.json(result); } }); }else{ res.json({no:0,msg:id+‘不存在‘}); } };
mongoose CastError: Cast to ObjectId failed for value
标签：
原文地址：http://www.cnblogs.com/yshyee/p/4583652.html
