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我有一個Invoice模型，它使用虛擬屬性來計算稅，小計，總計等的值。我遇到的問題是某些虛擬屬性需要能夠以引用其他虛擬屬性。如何使用Mongoose從另一個虛擬內部訪問虛擬屬性
例如，這裏是發票貓鼬模式：
var InvoiceSchema = Schema({
number: String,
customer: {ref:String, email:String},
invoiceDate: {type: Date, default: Date.now},
dueDate: {type: Date, default: Date.now},
memo: String,
message: String,
taxRate: {type:Number, default:0},
discount: {
value: {type:Number, default:0},
percent: {type:Number, default:0}
},
items: [ItemSchema],
payment: {type: Schema.Types.ObjectId, ref: 'Payment'}
});
InvoiceSchema.virtual('tax').get(function(){
var tax = 0;
for (var ndx=0; ndx<this.items.length; ndx++) {
var item = this.items[ndx];
tax += (item.taxed)? item.amount * this.taxRate : 0;
}
return tax;
});
InvoiceSchema.virtual('subtotal').get(function(){
var amount = 0;
for (var ndx=0; ndx<this.items.length; ndx++) {
amount += this.items[ndx].amount;
}
return amount;
});
InvoiceSchema.virtual('total').get(function(){
return this.amount + this.tax;
});
InvoiceSchema.set('toJSON', { getters: true, virtuals: true });
var ItemSchema = Schema({
product: String,
description: String,
quantity: {type: Number, default: 1},
rate: Number,
taxed: {type: Boolean, default: false},
category: String
});
ItemSchema.virtual('amount').get(function(){
return this.rate * this.quantity;
});
ItemSchema.set('toJSON', { getters: true, virtuals: true });
module.exports = mongoose.model('Invoice', InvoiceSchema);
我們理解這個問題看看對「稅」虛擬定義...
InvoiceSchema.virtual('tax').get(function(){
var tax = 0;
for (var ndx=0; ndx<this.items.length; ndx++) {
var item = this.items[ndx];
tax += (item.taxed)? item.amount * this.taxRate : 0;
}
return tax;
});
。 ..在這個例子中item.amount，當在一個虛擬內部調用時，不使用item.amount的虛擬獲取器。
是否有某種方法告訴Mongoose我需要使用getter而不是嘗試讀取不存在的屬性？