Mongoose高级自定义架构对象类型

I couldn't find any example of an advanced custom schema type involving custom objects (or value-objects) in Mongoose >=4.4.

我在Mongoose> = 4.4中找不到任何涉及自定义对象(或值对象)的高级自定义模式类型的示例。

Imagine that I want to use a custom type like:

想象一下,我想使用自定义类型:

function Polygon(c) {
  this.bounds = [ /* some data */ ];
  this.npoints = /* ... */
  /* ... initialize polygon ... */
};

Polygon.prototype.area = function surfaceArea() { /**/ };

Polygon.prototype.toObject = function toObject() { return this.bounds; };

Next, I implement a custom SchemaType like:

接下来,我实现了一个自定义SchemaType,如:

function PolygonType(key, options) {
  mongoose.SchemaType.call(this, key, options, 'PolygonType');
}

PolygonType.prototype = Object.create(mongoose.SchemaType.prototype);

PolygonType.prototype.cast = function(val) {
  if (!val) return null;
  if (val instanceof Polygon) return val;
  return new Polygon(val)
}

PolygonType.prototype.default = function(val) {
  return new Polygon(val);
}

How can I assure that:

我怎样才能保证:

1. Every time a new object is "hydrated" from db (mongoose init), I will have a Polygon instance and not a plain object. I understand it will use the cast function. assert(model.polygon instanceof Polygon)

   每当一个新对象从db(mongoose init)“水合”时,我将拥有一个Polygon实例,而不是一个普通对象。我知道它会使用强制转换功能。断言(model.polygon instanceof Polygon)

2. Every time I will save my Model the Polygon attribute should be encoded and stored as a plain object representation (Polygon.prototype.toObject()) that in this case is an Array object in mongodb.

   每次我保存我的模型时,Polygon属性应该被编码并存储为普通对象表示(Polygon.prototype.toObject()),在这种情况下是mongodb中的Array对象。

3. If I use model.toObject() it will recursively call the model.polygon.toObject() to have a full plain object representation of the document.

如果我使用model.toObject(),它将递归调用model.polygon.toObject()以获得文档的完整普通对象表示。

1 个解决方案

#1

I found a solution thanks to @vkarpov15 on github.com:

我在github.com上找到了@ vkarpov15的解决方案:

1. SchemaType.prototype.cast() is needed to correctly hydrate the document model from raw mongodb representation, and throw an error in case of invalid data.

   需要SchemaType.prototype.cast()才能从原始mongodb表示中正确地保存文档模型,并在数据无效时抛出错误。

2. To customize mongodb persistence, I had to implement a toBSON() function in my custom type object prototype (i.e. Polygon).

   要自定义mongodb持久性,我必须在自定义类型对象原型(即Polygon)中实现toBSON()函数。

3. model.toObject() / model.toJSON() currently doesn't call recursively toObject()/toJSON() on all children, but it looks like it will be fixed. But I could overload it as temporary workaround assigning a custom schema.methods.toObject() instance method.

   model.toObject()/ model.toJSON()当前不会在所有子节点上递归调用toObject()/ toJSON(),但看起来它将被修复。但我可以将其作为临时解决方法重载,分配自定义schema.methods.toObject()实例方法。