blocks|key|4156050|text|实例方法、静态方法或虚拟化都不存储在数据库中。方法和虚拟人之间的区别在于，虚拟者被像属性一样地访问，方法被称为类似函数。实例/静态与虚拟没有区别，因为在类上访问虚拟静态属性是没有意义的，但是在类上有一些静态实用程序或工厂方法是有意义的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4156051|var+PersonSchema+=+new+Schema({
++name:+{
++++first:+String,
++++last:+String
++}
});

PersonSchema.virtual('name.full').get(function+()+{
++return+this.name.first+%2B+'+'+%2B+this.name.last;
});

var+Person+=+mongoose.model('Person',+PersonSchema);

var+person+=+new+Person({
++name:+{
++++first:+'Alex',
++++last:+'Ford'
++}
});

console.log(person.name.full);

//+would+print+"Alex+Ford"+to+the+console|code-block|syntax|javascript|4156052|而方法被称为正常函数。|4156053|PersonSchema.method('fullName',+function+()+{
++return+this.name.first+%2B+'+'+%2B+this.name.last;
});

var+person+=+new+Person({
++name:+{
++++first:+'Alex',
++++last:+'Ford'
++}
});

console.log(person.fullName());

//+notice+this+time+you+call+fullName+like+a+function|4156054|您还可以“设置”虚拟属性，就像您习惯于使用常规属性一样。只需调用.get和.set来设置这两个操作的功能。注意，在.get中，您返回一个值，而在.set中，您接受一个值，并使用它来设置文档上的非虚拟属性。|offset|length|style|CODE|4156055|PersonSchema
++.virtual('name.full')
++.get(function+()+{
++++return+this.name.first+%2B+'+'+%2B+this.name.last;
++})
++.set(function+(fullName)+{
++++var+parts+=+fullName.split('+');
++++this.name.first+=+parts[0];
++++this.name.last+=+parts[1];
++});

var+person+=+new+Person({
++name:+{
++++first:+'Alex',
++++last:+'Ford'
++}
});

console.log(person.name.first);

//+would+log+out+"Alex"

person.name.full+=+'Billy+Bob';

//+would+set+person.name.first+and+person.name.last+appropriately

console.log(person.name.first);

//+would+log+out+"Billy"|4156056|从技术上讲，您可以对所有东西使用方法，而从不使用虚拟属性，但是对于某些事情来说，虚拟属性是很优雅的，比如我在这里展示的关于person.name.full的例子。|4156057|entityMap^0|0|0|0|0|W|4|11|4|1L|4|20|4|0|0|1P|G|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|10|8|@$M|11|N|12|O|P]|$M|13|N|14|O|P]|$M|15|N|16|O|P]|$M|17|N|18|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|D|7|19|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|1A|8|@$M|1B|N|1C|O|P]]|9|@]|A|$]]|$1|U|3|-4|5|6|7|1D|8|@]|9|@]|A|$]]]|V|$]]

Neither Instance methods, static methods, or virtuals are stored in the database. The difference between methods and virtuals is that virtuals are accessed like properties and methods are called like functions. There's no distinction between instance/static with virtuals because it makes no sense to have a virtual static property accessible on the class, but it does make sense to have some static utility or factory methods on the class.

<pre><code>var PersonSchema = new Schema({
 name: {
 first: String,
 last: String
 }
});

PersonSchema.virtual('name.full').get(function () {
 return this.name.first + ' ' + this.name.last;
});

var Person = mongoose.model('Person', PersonSchema);

var person = new Person({
 name: {
 first: 'Alex',
 last: 'Ford'
 }
});

console.log(person.name.full);

// would print "Alex Ford" to the console
</code></pre>

<hr>

Whereas methods are called like normal functions.

<pre><code>PersonSchema.method('fullName', function () {
 return this.name.first + ' ' + this.name.last;
});

var person = new Person({
 name: {
 first: 'Alex',
 last: 'Ford'
 }
});

console.log(person.fullName());

// notice this time you call fullName like a function
</code></pre>

<hr>

You can also "set" virtual properties like you're used to with regular properties. Just call <code>.get</code> and <code>.set</code> to setup the functionality for both actions. Notice in the <code>.get</code> you return a value, whereas in the <code>.set</code> you accept a value and use it to set non-virtual properties on your document.

<pre><code>PersonSchema
 .virtual('name.full')
 .get(function () {
 return this.name.first + ' ' + this.name.last;
 })
 .set(function (fullName) {
 var parts = fullName.split(' ');
 this.name.first = parts[0];
 this.name.last = parts[1];
 });

var person = new Person({
 name: {
 first: 'Alex',
 last: 'Ford'
 }
});

console.log(person.name.first);

// would log out "Alex"

person.name.full = 'Billy Bob';

// would set person.name.first and person.name.last appropriately

console.log(person.name.first);

// would log out "Billy"
</code></pre>

<hr>

You could technically use methods for everything and never use virtual properties, but virtual properties are elegant for certain things such as the examples I've shown here with <code>person.name.full</code>.

blocks|key|540572|text|我试图找出何时使用虚拟程序以及何时使用实例，并将其总结如下：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|540573|Static-用于不需要运行模型实例的方法(操作)。或者，针对模型的通用操作。|offset|length|style|BOLD|540574|找到一份文件，列出所有的文件。|540575|实例-用于确实需要模型实例的方法(操作)。|540576|例如，根据当前实例数据查找或检索数据。与与实例关联的其他文档一样。model.getRelatedDocs()|540577|虚拟-用于读取模型的属性，并在代码级别表明这些属性是属性/属性而不是方法。另外，对于基于已经加载到实例中的数据的组合属性。例如，胰脏的全名例子。|540578|entityMap^0|0|0|6|0|0|0|2|0|0|0|2|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|S|8|@$D|T|E|U|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|V|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|W|8|@$D|X|E|Y|F|G]]|9|@]|A|$]]|$1|L|3|M|5|6|7|Z|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|10|8|@$D|11|E|12|F|G]]|9|@]|A|$]]|$1|P|3|-4|5|6|7|13|8|@]|9|@]|A|$]]]|Q|$]]

I was trying to figure out when to use Virtuals and when to use Instances and I would summarize it like this: 

Statics - For methods (operations) that require no instance of a model to be run. Or, generic operations against the model. 

e.g. finding a document, listing all documents. 

Instances - For methods (operations) that do require an instance of the model to be present. 

e.g. finding or retrieving data based on the current instance data. Like other documents associated with the instance. model.getRelatedDocs()

Virtuals - For reading properties of the model and making it clear at code level that those are properties/attributes and not methods. Also, for composed properties based on data that is already loaded in the instance. e.g. the trypical full name example.

I understand that <code>static</code> methods are <code>Class Methods</code>, and that <code>methods</code> are <code>Instance Methods</code> and that <code>Virtuals</code> are also like <code>Instance Methods</code> but they are not stored in the database.

However, I would like to know if that is the only difference between <code>methods</code> and <code>virtuals</code>. Is there something else that I'm missing?

Virtuals vs Methods in Mongoose

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我理解static方法是Class Methods，methods是Instance Methods，Virtuals也像Instance Methods，但它们没有存储在数据库中。但是，我想知道这是否是methods和virtuals之间唯一的区别。还有什么是我遗漏的吗？

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