在存儲過程中獲取多個文檔（Azure DocumentDB）

Question

我有兩種文檔類型，清單和產品。一上市對象包含了某些國家的產品列表，像這樣：

上市：

{ 
    "Name": "Default", 
    "Countries": { 
    "_default": [ 
     "4QlxAPFcCAAPAAAAAAAAAA==", 
     "4QlxAPFcCAAHAAAAAAAAAA==" 
    ], 
    "US": [ 
     "4QlxAPFcCAAIAAAAAAAAAA==", 
     "4QlxAPFcCAAHAAAAAAAAAA==" 
    ] 
    }, 
    "Type": "Listing", 
    "id": "dfed1839-07c5-482b-81c5-669b1dbcd0b6", 
    "_rid": "4QlxAPFcCAAEAAAAAAAAAA==" 
} 

產品：

{ 
    "Name": "Widget", 
    "Price": 3.45, 
    "Type": "Product", 
    "_rid": "4QlxAPFcCAAHAAAAAAAAAA==" 
} 

我的目標是創建一個存儲過程Azure DocumentDB集合中的採用兩個參數rid和country，它們基本上會以最有效的方式獲取上市文件和該國的文件。我的推測是，使用getContext().getCollection().readDocument(...)通過其資源ID加載文檔將是最快的方式，因此試圖爲此創建存儲過程。

我的嘗試是使用帶有yield的發生器/迭代器，然後用純粹的方法嵌套連續調用（callback hell？）。所有的嘗試都給出了相同的結果：

它將獲取第一個文檔，但會在收到文檔後非常突然地結束。

供參考，這是我的最新嘗試：

function test(rid, country) { 
    var collection = getContext().getCollection(); 
    var collectionSelfLink = collection.getSelfLink(); 
    var docsLink = collectionSelfLink + "docs/"; 
    var body = getContext().getResponse().setBody; 

    function getDocument(rid) { 
     return new Promise(function(resolve, reject) { 
      var accepted = collection.readDocument(docsLink + rid, (err, doc, opts) => { 
       resolve(doc); 
      }); 

      if (!accepted) 
       reject("Not accepted");    
     }); 
    } 

    getDocument(rid) 
     .then(doc => { 
      body("0. First step"); // set test body 

      // Countries is a Dictionary<string, string[]> with resource ids 
      return doc.Countries[country] || doc.Countries["_default"]; 
     }) 
     // This is how far it gets, resulting in response "1. Documents to fetch: 2" 
     .then(a => body("1. Documents to fetch: " + a.length)) 
     .then(a => a.map(function(productId) { return getDoument(productId); })) 
     .then(a => body("2. It should come this far, right?")) 
     .then(a => Promise.all(a)) 
     .then(a => body(a)) 
     .catch(function(e) { throw new Error(JSON.stringify(e)); }); 
} 

Answer 1

事實證明，嵌套調用做其實工作中，如果你改變了反應身體經常

以下程序（？）按預期工作：

function test(rid, country) { 
    var collection = getContext().getCollection(); 
    var collectionSelfLink = collection.getSelfLink(); 
    var docsLink = collectionSelfLink + "docs/"; 
    var body = getContext().getResponse().setBody; 

    var accepted = collection.readDocument(docsLink + rid, (err, doc, opts) => { 
     if (err) throw new Error(err.message); 

     // Countries is a Dictionary<string, string[]> with resource ids 
     var offerIds = doc.Countries[country] || doc.Countries["_default"]; 
     var result = []; 

     for (var docId of offerIds) { 
      var subAccepted = 
       collection.readDocument(docsLink + docId, (err, doc, opts) => { 
        if (err) throw new Error(err.message); 

        result.push(doc); 
       }); 

      if (!subAccepted) 
       throw new Error("A subsequent request was not accepted"); 

      body(result); // <-- Note, setting body in each iteration. 
     } 
    }); 

    if (!accepted) 
     throw new Error("The request was not accepted"); 
}