如何計算骨幹中特定模型（屬性）的總和

Question

我是Backbone的新手，面臨一個問題，我需要在我的集合中計算模型的具體值。

作爲參考，我粘貼了一系列帳戶，從中我需要計算所有模型的總和acquisitionCost,units和netGainLoss。

即在計算acquisitionCost之後，我應該得到：1900，我們需要注意的一件事是值是以字符串形式顯示，如JSON中所示。

{ 
    "accounts": [{ 
      "accountNumber": "AS10000642", 
      "assets": [{ 
       "assetName": "ABCDEF GHIJKLM", 
       "isin": "GB0008533564", 
       "grossProfit": [{ 
        "acquisitionCost": "500", 
        "units": "10", 
        "netGainLoss": "20" 
       }] 
      }] 
     }, 
     { 
      "accountNumber": "AS10000642", 
      "assets": [{ 
       "assetName": "ABCDEF GHIJKLM", 
       "isin": "GB0008533564", 
       "grossProfit": [{ 
        "acquisitionCost": "1000", 
        "units": "10", 
        "netGainLoss": "20" 
       }] 
      }] 
     }, 
     { 
      "accountNumber": "AS10000407", 
      "assets": [{ 
       "assetName": "ABCDEF GHIJKLM", 
       "isin": "GB0008533564", 
       "grossProfit": [{ 
        "acquisitionCost": "400", 
        "units": "10", 
        "netGainLoss": "20" 
       }] 
      }] 
     } 
    ] 
} 

Answer 1

關於骨幹網的一個令人困惑的部分是，一個特定的實現可以用十億種方式完成，但仍然可以是正確的。所以開發人員可以選擇最佳的方法來確保它是模塊化的並且可以擴展以供將來使用。

由於呈現的數據是深嵌套的，因此最好將它們組織到集合或模型的集合和模型中。這樣可以很容易地操作並在其上添加更多功能。您可以將模型視爲小型船舶（資產或利潤）所在的monthership（賬戶）。因此，遵循該結構，給我們這種模式

還需要確保帳號是唯一的，否則，重複將不會被添加到集合。

// Profit Model 
var Profit = Backbone.Model.extend({}); 

// Asset Model 
var Asset = Backbone.Model.extend({ 
    parse: function(resp) { 
    if (resp.grossProfit) { 
     this.profit = new Profit(resp.grossProfit); 

     delete resp.grossProfit; 
    } 

    return resp; 
    } 
}); 

// Assets Collection 
var Assets = Backbone.Collection.extend({ 
    model: Asset 
}); 

// Account Model 
var Account = Backbone.Model.extend({ 
    idAttribute: 'accountNumber', 
    parse: function(resp) { 
    if (resp.assets) { 
     this.assets = new Assets(resp.assets, { 
     parse: true 
     }); 

     delete resp.assets; 
    } 

    return resp; 
    } 
}); 

// Accounts Collections 
var Accounts = Backbone.Collection.extend({ 
    model: Account, 
    getTotals: function() { 
    var acquisitionCost = 0; 
    var units = 0; 
    var netGainLoss = 0; 

    // iterate over the accounts collections 
    this.each(function(account) { 
     // iterate over assets collections for each account 
     account.assets.each(function(asset) { 
     var profit = asset.profit; 
     if (profit) { 
      acquisitionCost += parseInt(profit.get('acquisitionCost'), 10); 
      units += parseInt(profit.get('units'), 10); 
      netGainLoss += parseInt(profit.get('netGainLoss'), 10); 
     } 

     }); 
    }); 

    return { 
     acquisitionCost: acquisitionCost, 
     units: units, 
     netGainLoss: netGainLoss 
    }; 
    } 
}); 

var data = { 
    "accounts": [{ 
    "accountNumber": "AS10000642", 
    "assets": { 
     "assetName": "ABCDEF GHIJKLM", 
     "isin": "GB0008533564", 
     "grossProfit": { 
     "acquisitionCost": "500", 
     "units": "10", 
     "netGainLoss": "20" 
     } 

    } 
    }, { 
    "accountNumber": "AS100006423", 
    "assets": { 
     "assetName": "ABCDEF GHIJKLM", 
     "isin": "GB0008533564", 
     "grossProfit": { 
     "acquisitionCost": "1000", 
     "units": "10", 
     "netGainLoss": "20" 
     } 

    } 
    }, { 
    "accountNumber": "AS10000407", 
    "assets": { 
     "assetName": "ABCDEF GHIJKLM", 
     "isin": "GB0008533564", 
     "grossProfit": { 
     "acquisitionCost": "400", 
     "units": "10", 
     "netGainLoss": "20" 
     } 

    } 
    }] 
}; 

var accounts = new Accounts(data.accounts, { 
    parse: true 
}); 

var getTotalData = accounts.getTotals(); 

console.log("Total acqisition cost - " + getTotalData.acquisitionCost); 
console.log("Total units - " + getTotalData.units); 
console.log("Total net gain loss - " + getTotalData.netGainLoss); 

Check Fiddle