如何調用兩個GET Web API REST方法，第一個獲得第二個將返回的記錄數？

Question

我知道這很麻煩，但是在我現有的Web API客戶端代碼中，我停止讀取記錄的方式是當我對webRequest.GetResponse（）的調用在讀取和查找均未崩潰並吃掉異常時崩潰（我正在讀取“塊/ chunk”，這是由於調用Web API REST方法的手持設備的帶寬限制所致。

由於我的良心（可以這么說）困擾着我這樣做（但確實有效！），我想也許我可以先獲得記錄的數量，並利用該知識來阻止閱讀超出世界的邊緣，從而避免異常。

但是，如下所示： 為什么我的Web API路由被重新路由/錯誤地路由？ ，嘗試訪問多個GET方法沒有成功-我只能通過消除另一個來獲得所需的GET方法！

我現有的客戶代碼是：

private void buttonGetInvItemsInBlocks_Click(object sender, EventArgs e)
{
    string formatargready_uri = "http://localhost:28642/api/inventoryItems/{0}/{1}";
    // Cannot start with String.Empty or a blank string (" ") assigned to lastIDFetched; they both fail for some reason - Controller method is not even called. Seems like a bug in Web API to me...
    string lastIDFetched = "0"; 
    const int RECORDS_TO_FETCH = 100; 
    bool moreRecordsExist = true;

    try
    {
        while (moreRecordsExist) 
        {
            formatargready_uri = string.Format("http://localhost:28642/api/InventoryItems/{0}/{1}", lastIDFetched, RECORDS_TO_FETCH);
            var webRequest = (HttpWebRequest)WebRequest.Create(formatargready_uri); 
            webRequest.Method = "GET";
            var webResponse = (HttpWebResponse)webRequest.GetResponse(); // <-- this throws an exception when there is no longer any data left

            // It will hit this when it's done; when there are no records left, webResponse's content is "[]" and thus a length of 2
            if ((webResponse.StatusCode != HttpStatusCode.OK) || (webResponse.ContentLength < 3)) {
                moreRecordsExist = false;
            }
            else // ((webResponse.StatusCode == HttpStatusCode.OK) && (webResponse.ContentLength > 2))
            {
                var reader = new StreamReader(webResponse.GetResponseStream());
                string s = reader.ReadToEnd();
                var arr = JsonConvert.DeserializeObject<JArray>(s);

                foreach (JObject obj in arr)
                {
                    string id = (string)obj["Id"];
                    lastIDFetched = id;
                    int packSize = (Int16)obj["PackSize"];
                    string description = (string)obj["Description"];
                    int dept = (Int16)obj["DeptSubdeptNumber"];
                    int subdept = (Int16)obj["InvSubdepartment"];
                    string vendorId = (string)obj["InventoryName"];
                    string vendorItem = (string)obj["VendorItemId"];
                    double avgCost = (Double)obj["Cost"];
                    double unitList = (Double)obj["ListPrice"];

                    inventoryItems.Add(new WebAPIClientUtils.InventoryItem
                    {
                        Id = id,
                        InventoryName = vendorId,
                        UPC_PLU = vendorId,
                        VendorItemId = vendorItem,
                        PackSize = packSize,
                        Description = description,
                        Quantity = 0.0,
                        Cost = avgCost,
                        Margin = (unitList - avgCost),
                        ListPrice = unitList,
                        DeptSubdeptNumber = dept,
                        InvSubdepartment = subdept
                    });
                    // Wrap around on reaching 100 with the progress bar; it's thus sort of a hybrid determinate/indeterminate value that is shown
                    if (progressBar1.Value >= 100)
                    {
                        progressBar1.Value = 0;
                    }
                    progressBar1.Value += 1;
                }
            } // if ((webResponse.StatusCode == HttpStatusCode.OK) && (webResponse.ContentLength > 0))
        } // while

        if (inventoryItems.Count > 0)
        {
            dataGridViewGETResults.DataSource = inventoryItems;
        }
        MessageBox.Show(string.Format("{0} results found", inventoryItems.Count));
    }
    catch (Exception ex)
    {
        // After all records are read, this exception is thrown, so commented out the message; thus, this is really *expected*, and is not an "exception"
        //MessageBox.Show(ex.Message);
    }
}

}

...並且Web API REST Controller代碼為：

public class InventoryItemsController : ApiController
{
    static readonly IInventoryItemRepository inventoryItemsRepository = new InventoryItemRepository();

    public IEnumerable<InventoryItem> GetBatchOfInventoryItemsByStartingID(string ID, int CountToFetch)
    {
        return inventoryItemsRepository.Get(ID, CountToFetch); 
    }

}

...和（im？）相關的存儲庫代碼為：

public IEnumerable<InventoryItem> Get(string ID, int CountToFetch)
{
    return inventoryItems.Where(i => 0 < String.Compare(i.Id, ID)).Take(CountToFetch);
}

有人會認為我可以有這樣一種方法：

public IEnumerable<InventoryItem> Get()
{
    return inventoryItems.Count();
}

...這將由於沒有參數而與其他參數不同而得到認可（即使沒有路由狂喜，昨天我進行的所有attempts靖嘗試也都以失敗告終）。

Answer 1

我發現我可以用以下代碼獲得記錄數：

客戶

private int getInvItemsCount()
{
    int recCount = 0;
    const string uri = "http://localhost:28642/api/InventoryItems";
    var webRequest = (HttpWebRequest)WebRequest.Create(uri);
    webRequest.Method = "GET";
    using (var webResponse = (HttpWebResponse)webRequest.GetResponse())
    {
        if (webResponse.StatusCode == HttpStatusCode.OK)
        {
            var reader = new StreamReader(webResponse.GetResponseStream());
            string s = reader.ReadToEnd();
            Int32.TryParse(s, out recCount);
        }
    }
    return recCount;
}

private void GetInvItemsInBlocks()
{
    Cursor.Current = Cursors.WaitCursor;
    try
    {
        string lastIDFetched = "0";
        const int RECORDS_TO_FETCH = 100;
        int recordsToFetch = getInvItemsCount();
        bool moreRecordsExist = recordsToFetch > 0;
        int totalRecordsFetched = 0;

        while (moreRecordsExist)
        {
            string formatargready_uri = string.Format("http://localhost:28642/api/InventoryItems/{0}/{1}", lastIDFetched, RECORDS_TO_FETCH);
            var webRequest = (HttpWebRequest)WebRequest.Create(formatargready_uri);
            webRequest.Method = "GET";
            using (var webResponse = (HttpWebResponse)webRequest.GetResponse())
            {
                if (webResponse.StatusCode == HttpStatusCode.OK)
                {
                    var reader = new StreamReader(webResponse.GetResponseStream());
                    string s = reader.ReadToEnd();
                    var arr = JsonConvert.DeserializeObject<JArray>(s);

                    foreach (JObject obj in arr)
                    {
                        var id = (string)obj["Id"];
                        lastIDFetched = id;
                        int packSize = (Int16)obj["PackSize"];
                        var description = (string)obj["Description"];
                        int dept = (Int16)obj["DeptSubdeptNumber"];
                        int subdept = (Int16)obj["InvSubdepartment"];
                        var vendorId = (string)obj["InventoryName"];
                        var vendorItem = (string)obj["VendorItemId"];
                        var avgCost = (Double)obj["Cost"];
                        var unitList = (Double)obj["ListPrice"];

                        inventoryItems.Add(new WebAPIClientUtils.InventoryItem
                        {
                            Id = id,
                            InventoryName = vendorId,
                            UPC_PLU = vendorId,
                            VendorItemId = vendorItem,
                            PackSize = packSize,
                            Description = description,
                            Quantity = 0.0,
                            Cost = avgCost,
                            Margin = (unitList - avgCost),
                            ListPrice = unitList,
                            DeptSubdeptNumber = dept,
                            InvSubdepartment = subdept
                        });
                        if (progressBar1.Value >= 100)
                        {
                            progressBar1.Value = 0;
                        }
                        progressBar1.Value += 1;
                    } // foreach
                } // if (webResponse.StatusCode == HttpStatusCode.OK)
            } // using HttpWebResponse
            int recordsFetched = WebAPIClientUtils.WriteRecordsToMockDatabase(inventoryItems, hs);
            label1.Text += string.Format("{0} records added to mock database at {1}; ", recordsFetched, DateTime.Now.ToLongTimeString());
            totalRecordsFetched += recordsFetched;
            moreRecordsExist = (recordsToFetch > (totalRecordsFetched+1));
        } // while
        if (inventoryItems.Count > 0)
        {
            dataGridViewGETResults.DataSource = inventoryItems;
        }
    }
    finally
    {
        Cursor.Current = Cursors.Default;
    }
}

服務器

倉庫接口：

interface IInventoryItemRepository
{
    . . .
    int Get();
    . . .
}

存儲庫接口實現：

public class InventoryItemRepository : IInventoryItemRepository
{
    private readonly List<InventoryItem> inventoryItems = new List<InventoryItem>();
    . . .
    public int Get()
    {
        return inventoryItems.Count;
    }
    . . .
}

控制器：

static readonly IInventoryItemRepository inventoryItemsRepository = new InventoryItemRepository();

public int GetCountOfInventoryItems()
{
    return inventoryItemsRepository.Get();
}