使用反射和泛型改進代碼

使用以下代碼，如何使用反射和泛型提高其可讀性？這是很多重復的代碼，但我對這些概念很陌生。“dl”是一個介面，但我不確定為什么我無法使用 .getType().getProperties() 訪問我想要的屬性，它回傳一個空串列。

if (entity == "SERVICE")
{
    if (filter == "Active == 1")
    {
        foreach (var service in dl.Services.List().Where(x => x.Active).OrderBy(x => x.Name))
            tmpReturn.Add(service.ID, service.Name);

        return tmpReturn;
    }

    foreach (var service in dl.Services.List().OrderBy(x => x.Name))
        tmpReturn.Add(service.ID, service.Name);

    return tmpReturn;
}

if (entity == "CAMPAIGN")
{
    if (filter == "Active == 1")
    {
        foreach (var campaign in dl.Campaigns.List().Where(x => x.Active).OrderBy(x => x.Name))
            tmpReturn.Add(campaign.ID, campaign.Name);

        return tmpReturn;
    }

    foreach (var campaign in dl.Campaigns.List().OrderBy(x => x.Name))
        tmpReturn.Add(campaign.ID, campaign.Name);

    return tmpReturn;
}

if (entity == "AGENT")
{
    if (condition == "Active != ")
    { 
        if (value == "1")
        { 
            foreach (var agent in dl.Agents.List().OrderBy(x => x.Name))
                tmpReturn.Add(agent.ID, agent.Name);

            return tmpReturn;
        }

        foreach (var agent in dl.Agents.List().Where(x => x.Active).OrderBy(x => x.Name))
            tmpReturn.Add(agent.ID, agent.Name);

        return tmpReturn;
    }
    else if (condition == "Active == ")
    {
        if (value == "1")
        {
            foreach (var agent in dl.Agents.List().Where(x => x.Active).OrderBy(x => x.Name))
                tmpReturn.Add(agent.ID, agent.Name);

            return tmpReturn;
        }

        foreach (var agent in dl.Agents.List().OrderBy(x => x.Name))
            tmpReturn.Add(agent.ID, agent.Name);

        return tmpReturn;
    }
}

uj5u.com熱心網友回復：

由于不同的物體沒有實作共同的介面，我們使用ValueTuples作為中間結果。我不確定 ID 型別是什么。我在int這里假設，但你可以很容易地改變它。

IEnumerable<(int ID, string Name, bool Active)> source;
bool filterByActive;
switch (entity) {
    case "SERVICE":
        source = dl.Services.List().Select(x => (x.ID, x.Name, x.Active));
        filterByActive = filter == "Active == 1";
        break;
    case "CAMPAIGN":
        source = dl.Campaigns.List().Select(x => (x.ID, x.Name, x.Active));
        filterByActive = filter == "Active == 1";
        break;
    case "AGENT":
        source = dl.Agents.List().Select(x => (x.ID, x.Name, x.Active));
        filterByActive = condition == "Active != " && value != "1" ||
                         condition == "Active == " && value == "1";
        break;
    default:
        throw new NotImplementedException();
}
if (filterByActive) {
    source = source.Where(x => x.Active);
}
return source
    // .OrderBy(x => x.Name)       Not for Dictionary!
    .ToDictionary(x => x.ID, x => x.Name);

這個想法是我們回傳一個表示資料源的列舉和一個布林值，告訴我們是否必須在 switch 陳述句中進行過濾。然后可以在此資料源上執行所有其他操作。

Where我們可以通過單獨應用來組成可列舉。

使用 LINQ 擴展方法ToDictionary()而不是在回圈中添加單個元素可以進一步簡化事情。請注意，如果您將內容添加到字典中，則對專案進行排序無效。

uj5u.com熱心網友回復：

我認為您不需要反射或泛型：（我沒有在以下代碼片段中撰寫型別，因為我不能總是從您的代碼中推斷出它們。）

List getTmpReturn(list, bool isActive){
    if (isActive){
        foreach (var item in list.List().Where(x => x.Active).OrderBy(x => x.Name))
             tmpReturn.Add(item.ID, item.Name);
    }
    else {
        foreach (var item in list.List().OrderBy(x => x.Name))
            tmpReturn.Add(item.ID, item.Name);
    }
    return tmpReturn;
}

switch(entity):
    case "SERVICE":
        return getTmpReturn(dl.Services, filter == "Active == 1");
    case "CAMPAIGN":
        return getTmpReturn(dl.Campaigns, filter == "Active == 1");
    case "AGENT":
        bool isActive = (condition == "Active != " && value != "1") || (condition == "Active == " && value == "1");
        return getTmpReturn(dl.Agents, isActive);

標籤：C＃ 仿制药 反射 干燥 代码可读性

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