数字类型错误与猫鼬模型

500 内部服务器错误，Error: TypeError: path must be a string

浏览器控制台指向 ItemCtrl.js：35

console.log('Error: ' + data);

错误的堆栈跟踪如下所示：

类型错误：路径必须是字符串 at Query.where （/Users/Name/Downloads/dev/v16/node_modules/mongoose/lib/query.js：593：11） at Function.where （/Users/Name/Downloads/dev/v16/node_modules/mongoose/lib/model.js：1040：18） 在模型。（/用户/名称/下载/dev/v16/应用程序/模型/项目.js：44：35） ...

错误似乎来自/app/models/item中的一行.js特别是在else if声明中。因为随着else if被注释掉，if和else都有效。

// load mongoose since we need it to define a schema and model
var mongoose = require('mongoose');
var ItemSchema = mongoose.Schema({
    title : String,
    position: Number
});
// before validation starts, the number of Items is counted..afterwards, the position is set
ItemSchema.pre("validate", function(next) {
    var doc = this;
    // if 'position' is not filled in, fill it in
    // not using !position because 0 might be a valid value
    if(typeof doc.position !== "number") {
        // count the number of Items *
        // use mongoose.model to fetch the model because it is not compiled yet
        mongoose.model("Item").count(function(err, num) {
            // if there was an error, pass it to next()
            if(err)
                return next(err);
            // set the position, then call next();
            doc.position = num;
            return next();
        });
    } else if(typeof doc.position == "number") {
        console.log('yes, a number');
        // check if there is an existing document with the same position
        // use mongoose.model to fetch the model because the model is not compiled yet
        mongoose.model("Item").where({_id: {$ne: doc._id}, position: doc.position}).count( function (err, count) {
            // if there was an error, pass it to next()
            if(err)
                return next(err);
            // if there is a doc with the SAME position, execute an update to MOVE DOWN all the $gte docs
            if(count > 0) {
                // use mongoose.model to fetch the model because the model is not compiled yet
                mongoose.model("Item").update({position: {$gte: doc.position}}, {position: {$inc: 1}}, {multi: 1}, function(err, numAffected) {
                    console.log(numAffected);
                    // Call next() (with or without an error)
                    next(err);
                });
            } else {
                //  there are no docs that need to move down, so call next()
                next();
            }
        });
    } else {
        //  there is no need to count or update positions, so call next()
        next();
    }
});
module.exports = mongoose.model('Item', ItemSchema);

• 数据的路径是这样的：
• /public/views/CreateItem.html 中的表单域
• 到/public/js/controllers/ItemCtrl.js
• to/public/js/services/ItemService.js
• 到/app/routes.js
• 到/app/models/item.js
• 并且数据可以在本地主机：8080/API/Items 的 JSON 中查看

/public/views/CreateItem.html

<form>
    <div class="form-group">
        <!-- BIND THESE VALUES TO formData.value IN ANGULAR -->
        <input type="text" class="form-control input-lg text-center" placeholder="Item" ng-model="formData.title">
        <input type="number" class="form-control input-lg text-center" placeholder="0" ng-model="formData.position">
    </div>
    <!-- createItem() WILL CREATE THE NEW ITEM VIA ANGULAR THROUGH NODE API TO MONGOOSE -->
    <button type="submit" class="btn btn-primary btn-lg" ng-click="createItem()">Add Item</button>
</form>

public/js/controllers/ItemCtrl.js

angular.module('ItemCtrl', [])
// inject the Item service.factory into our controller
.controller('ItemController', function($scope, $http, Items, isEmptyObjectFilter) {
        $scope.formData = {};
        // CREATE ==================================================================
        // when submitting the add form, send the text to the node API
        $scope.createItem = function() {
                // validate the formData (using our exentions.js .filter) to make sure that something is there..if form is empty, nothing will happen
                if (!isEmptyObjectFilter($scope.formData)) {
                        // call the create function from our service (returns a promise object)
                        Items.create($scope.formData)
                                // if successful creation, call our get function to get all the new items
                                .success(function(data) {
                                        $scope.formData = {}; // clear the form so our user is ready to enter another
                                        $scope.items = data; // assign our new list of items
                                })
                                .error(function(data) {
                                        console.log('Error: ' + data);
                                });
                }
        };
});

public/js/services/ItemService.js

angular.module('ItemService', [])
// super simple service
// each function returns a promise object 
.factory('Items', function($http) {
    return {
        get : function() {
            return $http.get('/api/items');
        },
        create : function(itemData) {
            return $http.post('/api/items', itemData);
        }
    }
});

app/routes.js

// load the item model
var Item = require('./models/item');
// expose the routes to our app with module.exports
module.exports = function(app) {
    // create item and send back all items after creation
    app.post('/api/items', function(req, res) {
        console.log(req.body.position);
        // create an item, information comes from AJAX request from Angular
        Item.create({
            title : req.body.title,
            position : req.body.position
        }, function(err, item) {
            if (err)
                res.send(err);
            // get and return all the items after you create another
            Item.find(function(err, items) {
                if (err)
                    res.send(err)
                res.json(items);
            });
        });
    });
};