Node.js Mongoose：调用另一个模式的静态方法返回；TypeError:对象没有方法'；xxx和x27&引用；

在我的节点项目中，我定义了一个dog模式和一个cat模式

架构相同（名称/年龄）

两个模式都有一个静态方法sayHello。cat schame有一个实例方法let_dog_speak，它将触发dog模式的sayHello，let_cat_speak也是如此

在我的路由处理程序中，当我试图获取一个dog实例（/getdog/：name）时，将触发cat的sayHello方法，反之亦然

问题是我的猫能让狗说话，而狗不能。我在下面附上了我的代码和错误信息

/model/cat.js

var Dog = require('./dog');

var Cat = new Schema({
    name: { type:String, required:true, trim:true },
    age: { type:Number, required:true, trim:true }
});

Cat.statics.sayHello = function() {
    console.log("Meow meow");
};

Cat.methods.let_dog_speak = function() {
    Dog.sayHello();
};

var cat_model = testdb.model('cat_collection', Cat);
module.exports = cat_model;

var Cat = require('./cat');

var Dog = new Schema({
    name: { type: String, required: true, trim: true },
    age: { type: Number, required:true, trim:true },
});

Dog.statics.sayHello = function() {
    console.log("Wow wow");
};

Dog.methods.let_cat_speak = function() {
    Cat.sayHello();
};

var dog_model = testdb.model('dog_collection', Dog);
module.exports = dog_model;

app.get('/getdog/:name', function(req, res) {
    Dog.findOne({
        name: req.params.name
    }, function(error, dog) {
        dog.let_cat_speak(); //This throws error
        res.json(dog);
    });
});

app.get('/getcat/:name', function(req, res) {
    Cat.findOne({
        name: req.params.name,
    }, function(error, cat) {
        cat.let_dog_speak(); //This works, will print wow wow 
        res.json(cat);
    });
});

/model/dog.js

var Dog = require('./dog');

var Cat = new Schema({
    name: { type:String, required:true, trim:true },
    age: { type:Number, required:true, trim:true }
});

Cat.statics.sayHello = function() {
    console.log("Meow meow");
};

Cat.methods.let_dog_speak = function() {
    Dog.sayHello();
};

var cat_model = testdb.model('cat_collection', Cat);
module.exports = cat_model;

var Cat = require('./cat');

var Dog = new Schema({
    name: { type: String, required: true, trim: true },
    age: { type: Number, required:true, trim:true },
});

Dog.statics.sayHello = function() {
    console.log("Wow wow");
};

Dog.methods.let_cat_speak = function() {
    Cat.sayHello();
};

var dog_model = testdb.model('dog_collection', Dog);
module.exports = dog_model;

app.get('/getdog/:name', function(req, res) {
    Dog.findOne({
        name: req.params.name
    }, function(error, dog) {
        dog.let_cat_speak(); //This throws error
        res.json(dog);
    });
});

app.get('/getcat/:name', function(req, res) {
    Cat.findOne({
        name: req.params.name,
    }, function(error, cat) {
        cat.let_dog_speak(); //This works, will print wow wow 
        res.json(cat);
    });
});

这是我的路线，/route.js

var Dog = require('./dog');

var Cat = new Schema({
    name: { type:String, required:true, trim:true },
    age: { type:Number, required:true, trim:true }
});

Cat.statics.sayHello = function() {
    console.log("Meow meow");
};

Cat.methods.let_dog_speak = function() {
    Dog.sayHello();
};

var cat_model = testdb.model('cat_collection', Cat);
module.exports = cat_model;

var Cat = require('./cat');

var Dog = new Schema({
    name: { type: String, required: true, trim: true },
    age: { type: Number, required:true, trim:true },
});

Dog.statics.sayHello = function() {
    console.log("Wow wow");
};

Dog.methods.let_cat_speak = function() {
    Cat.sayHello();
};

var dog_model = testdb.model('dog_collection', Dog);
module.exports = dog_model;

app.get('/getdog/:name', function(req, res) {
    Dog.findOne({
        name: req.params.name
    }, function(error, dog) {
        dog.let_cat_speak(); //This throws error
        res.json(dog);
    });
});

app.get('/getcat/:name', function(req, res) {
    Cat.findOne({
        name: req.params.name,
    }, function(error, cat) {
        cat.let_dog_speak(); //This works, will print wow wow 
        res.json(cat);
    });
});

错误消息：

TypeError: Object #<Object> has no method 'sayHello'
    at model.Dog.methods.let_cat_speak (/home/sliter/Development/nodeJS/mongotest/backend/model/dog.js:16:9)

TypeError:对象#没有方法“sayHello”
在model.Dog.methods.let_cat_speak（/home/slitter/Development/nodeJS/mongotest/backend/model/Dog.js:16:9）

这可能是因为cat.js和dog.js之间的循环引用。将它们放在同一个文件中，然后再试一次。多亏了@sza，通过集成这两个文件解决了这个问题。此外，我还发现了这个链接，它解释了问题的原因。简言之，正是nodejs禁止引用循环。为了保留两个文件，将require（'./dog | cat'）语句替换为mongoose.model（'dog | cat| collection'）将使代码正常工作。不客气，我很高兴您解决了问题。