Question

我正在使用iTunes / amazon / googlePlay联盟计划，并希望将AffiliateCode添加到我在Web服务中的ExternalLinks表中的URL。这意味着web服务首先使用id_cd收集来自ExternalLinks [Table]的不同可用链接，之后需要遍历AffiliateProgram [Table]，以便比较是否有可用的匹配联盟计划。

ExternalLink[Table]
public int id_external_link { get; set; }
public int id_cd { get; set; }
public string Name { get; set; }
public string URL { get; set; }

AffiliateProgram[Table]
public int ID { get; set; }
public string AffiliateName { get; set; }
public string AffiliateSite { get; set; }
public string AffiliateCode { get; set; }
public Nullable<int> CodePosition { get; set; }

AffiliateProgram [表] AffiliateName和ExternalLinks [表]名称始终相同。

这就是我设置它的方式，但我还没有让它工作，并且在最后几天卡住了。

[Route("api/Cds/ExternalLinks/{id_cd}")]
    public async Task<List<ExternalLink>> GetAllExternalLinks(int id_cd)
    {
        List<ExternalLink> externallinks = await db.ExternalLink
            .Where(EL => EL.id_cd == id_cd)
            .ToListAsync();

        List<ExternalLink> ListAllExternalLinks = new List<ExternalLink>();
        for (int i = 0; i < 4; i++)
        {
           ExternalLink CDEL = new ExternalLink();

           if (CDEL.Name == "Itunes") {   

           var query = from EL in db.ExternalLink
                       join AP in db.AffiliateProgram on EL.Name equals AP.AffiliateName
                       select new
                       {
                        AffiliateName = AP.AffiliateName,
                        Name = EL.Name,
                        AffilateCode = AP.AffiliateCode,
                        URL = EL.URL
                       };

            URL = query.First().Name + "?mt=1&at=" + query.First().AffiliateCode + "&ct=" + id_cd;  

            }

            ListAllExternalLinks.Add(CDEL);

        }   
        ListAllExternalLinks.AddRange(externallinks);
        return ListAllExternalLinks;
    }

这会在postmaster中产生以下结果，其中包含4个空结果：

[
{},
{},
{},
{},
{
"id_external_link": 1459,
"id_cd": 13376,
"name": "Itunes",
"url": "https://itunes.apple.com/...countingcrows"
},
{
"id_external_link": 1460,
"id_cd": 13376,
"name": "Amazon",
"url": "https://www.amazon.com/....countingcrows"
},
{
"id_external_link": 1461,
"id_cd": 13376,
"name": "GooglePlay",
"url": "https://play.google.com/...countingcrows"
}
]

Answer 1

您的查询是returning an anonymous object，并且您正在访问查询未返回的属性。您可以更改查询以返回以下属性，然后访问它们：

        var query = from EL in db.ExternalLink
                    join AP in db.AffiliateProgram on EL.Name equals AP.AffiliateName
                    select new
                    {
                        AffiliateName = AP.AffiliateName
                        Name = EL.Name
                        AffiliateCode = AP.AffiliateCode
                    };

Answer 2

您有许多语法错误会阻止此代码进行编译，因此通常很难弄清楚您出错的确切位置。至少要确保您的代码首先编译，然后如果您仍未获得所需的结果，我们可以为您提供帮助。

那就是说，看起来你要比现在更困难。如果您希望能够加入这两个表，则应在它们之间创建一个外键。如果特定链接属于特定联盟计划，则实际创建该关系：

public class ExternalLink
{
    ...

    [ForeignKey("AffiliateProgram")]
    public int AffiliateProgramId { get; set; }
    public virtual AffiliateProgram AffiliateProgram { get; set; }
}

然后，您可以在查询并在一天中调用它时简单地包含联盟计划：

var externalLinks = db.ExternalLinks
    .Include(m => m.AffiliateProgram)
    .Where(m => m.id_cd == id_cd)
    .ToListAsync();

然后，当您重复链接时：

var affiliateCode = link.AffiliateProgram.AffiliateCode;

超级简单。

Answer 3

好了它的工作（实际上必须改变很多东西），谢谢S.Dav的解释如何连接其他数据库表并用数据修改字符串。非常有用的一课。

    [Route("api/CDS/ExternalLink/{id_cd}")]
    public async Task<List<ExternalLink>> GetAllExternalLinks(int id_cd)
    {

        List<ExternalLink> ListAllExternalLinks = new List<ExternalLink>();

            foreach (var item in await db.ExternalLink
                .Where(EL => EL.id_cd == id_cd)
                .ToListAsync())
            {

            ExternalLink CDEL = new ExternalLink();

            CDEL.id_cd = item.id_cd;
            CDEL.Name = item.Name;

            if (CDEL.Name == "Itunes") {

                var query = from EL in db.ExternalLink
                        join AP in db.AffiliateProgram on EL.Name equals AP.AffiliateName
                        select new
                        {
                        AffiliateName = AP.AffiliateName,
                        Name = EL.Name,
                        AffilateCode = AP.AffiliateCode,
                        URL = EL.URL
                        };

                CDEL.URL = item.URL + query.First().Name + "?mt=1&at=" + query.First().AffilateCode + "&ct=" + id_cd;          
            }
            ListAllExternalLinks.Add(/CDEL);
        }
        return ListAllExternalLinks;
    }

在这种情况下，结果是一个完美的网络服务，联盟代码连接到iTunes :-)很想有一个解决方案，实际上可以找到联盟代码本身，但这现在适用： - ）

[
 {
"id_cd": 13376,
"name": "Itunes",
"url": "https://itunes.apple.com/...../countingcrows?mt=1&at=1010lmNu&ct=13376"
 },
 {
"id_cd": 13376,
"name": "Amazon"
"url": "https://www.amazon.com...../countingcrows"
 },
 {
"id_cd": 13376,
"name": "GooglePlay"
 "url": "https://play.google.com/....countingcrows?id=AEIKS4IbfNk&hl=en"
 }
]

MVC C＃Web服务连接两个表并组合输出

3 个答案: