C# 如何基于日期列获取最新信息并返回BuildMetrics类型的对象？_C#_Entity Framework

C# 如何基于日期列获取最新信息并返回BuildMetrics类型的对象？

c# entity-framework

C# 如何基于日期列获取最新信息并返回BuildMetrics类型的对象？,c#,entity-framework,C#,Entity Framework,我正在尝试检索SP、最新构建（基于时间戳）和宣布日期，如下所示，我需要以下方面的指导 1.如何根据软件产品构建表中发布日期（格式为2016-12-02 19:24:32）列中的时间戳获取最新构建？我尝试了以下方法，但无效 softwareBuildMetrics.LatestBuild = bitDB.software_product_builds.Where(x => x.software_product_build_id == softwareProductid).Select(x =

我正在尝试检索SP、最新构建（基于时间戳）和宣布日期，如下所示，我需要以下方面的指导

1.如何根据软件产品构建表中发布日期（格式为2016-12-02 19:24:32）列中的时间戳获取最新构建？我尝试了以下方法，但无效

softwareBuildMetrics.LatestBuild = bitDB.software_product_builds.Where(x => x.software_product_build_id == softwareProductid).Select(x => x.software_product_build).FirstOrDefault();

2.如何返回Build Metrics类型的对象，我认为当前的错误与此相关

public class BuildMetrics
{
    public string SP { get; set; }
    public string LatestBuild { get; set; }
    public string AnnouncedDate { get; set; }

}

方法：-

    public IEnumerable<BuildMetrics> GetBuildMetrics()
    {
        var bitDB = new BitDatabaseConnection().bitDB;
        List<BuildMetrics> softwareBuildMetrics = new List<BuildMetrics>();
         //Get unique list of software product ids
         var softwareProductIds = bitDB.software_products.Select(x => x.id).Distinct().ToList();
        foreach (var softwareProductid in softwareProductIds)
           {
               softwareBuildMetrics.SP = bitDB.software_products.Where(x => x.id == softwareProductid).Select(x => x.software_product).FirstOrDefault();
               softwareBuildMetrics.LatestBuild = bitDB.software_product_builds.Where(x => x.software_product_build_id == softwareProductid).Select(x => x.software_product_build).FirstOrDefault();
               softwareBuildMetrics.AnnouncedDate = bitDB.software_product_builds.Where(x => x.software_product_build_id == softwareProductid).Select(x => x.date_announced).FirstOrDefault();


            }
    }

public IEnumerable GetBuildMetrics（）
{
var bitDB=新的BitDatabaseConnection（）.bitDB；
List softwareBuildMetrics=新列表（）；
//获取软件产品ID的唯一列表
var softwareProductIds=bitDB.software_products.Select（x=>x.id）.Distinct（）.ToList（）；
foreach（softwareProductid中的var softwareProductid）
{
softwareBuildMetrics.SP=bitDB.software_products.Where（x=>x.id==softwareProductid）。选择（x=>x.software_product.FirstOrDefault（）；
softwareBuildMetrics.LatestBuild=bitDB.software\u product\u builds.Where（x=>x.software\u product\u build\u id==softwareProductid）。选择（x=>x.software\u product\u build）。FirstOrDefault（）；
softwareBuildMetrics.AnnouncedDate=bitDB.software\u product\u builds.Where（x=>x.software\u product\u build\u id==softwareProductid）。选择（x=>x.date\u announced）。FirstOrDefault（）；
}
}

错误：-

Error   1   'System.Collections.Generic.List<Dashboard.Model.ApiModels.BuildMetrics>' does not contain a definition for 'SP' and no extension method 'SP' accepting a first argument of type 'System.Collections.Generic.List<Dashboard.Model.ApiModels.BuildMetrics>' could be found (are you missing a using directive or an assembly reference?) C:\Users\gnakkala\gnakkala_dashboard\depot\software\projects\user_branches\gnakkala\Dashboard\Dashboard.Data.Repository\BuildRepositories\SoftwareProductRepository.cs  22  41  Dashboard.Data.Repository


Error   2   'System.Collections.Generic.List<Dashboard.Model.ApiModels.BuildMetrics>' does not contain a definition for 'LatestBuild' and no extension method 'LatestBuild' accepting a first argument of type 'System.Collections.Generic.List<Dashboard.Model.ApiModels.BuildMetrics>' could be found (are you missing a using directive or an assembly reference?)   C:\Users\gnakkala\gnakkala_dashboard\depot\software\projects\user_branches\gnakkala\Dashboard\Dashboard.Data.Repository\BuildRepositories\SoftwareProductRepository.cs  23  41  Dashboard.Data.Repository

Error   3   'System.Collections.Generic.List<Dashboard.Model.ApiModels.BuildMetrics>' does not contain a definition for 'AnnouncedDate' and no extension method 'AnnouncedDate' accepting a first argument of type 'System.Collections.Generic.List<Dashboard.Model.ApiModels.BuildMetrics>' could be found (are you missing a using directive or an assembly reference?)   C:\Users\gnakkala\gnakkala_dashboard\depot\software\projects\user_branches\gnakkala\Dashboard\Dashboard.Data.Repository\BuildRepositories\SoftwareProductRepository.cs  24  41  Dashboard.Data.Repository

错误1“System.Collections.Generic.List”不包含“SP”的定义，并且找不到接受“System.Collections.Generic.List”类型的第一个参数的扩展方法“SP”（是否缺少using指令或程序集引用？）C:\Users\gnakkala\gnakkala_dashboard\depot\software\Project\user_Branchs\gnakkala\dashboard\dashboard.Data.Repository\BuildRepositories\SoftwareProductRepository.cs 22 41 dashboard.Data.Repository
错误2“System.Collections.Generic.List”不包含“LatestBuild”的定义，并且找不到接受“System.Collections.Generic.List”类型的第一个参数的扩展方法“LatestBuild”（是否缺少using指令或程序集引用？）C:\Users\gnakkala\gnakkala_dashboard\depot\software\Project\user_Branchs\gnakkala\dashboard\dashboard.Data.Repository\BuildRepositories\SoftwareProductRepository.cs 23 41 dashboard.Data.Repository
错误3“System.Collections.Generic.List”不包含“AnnouncedDate”的定义，并且找不到接受“System.Collections.Generic.List”类型的第一个参数的扩展方法“AnnouncedDate”（是否缺少using指令或程序集引用？）C:\Users\gnakkala\gnakkala_dashboard\depot\software\Project\user_Branchs\gnakkala\dashboard\dashboard.Data.Repository\BuildRepositories\SoftwareProductRepository.cs 24 41 dashboard.Data.Repository

这不是向列表中添加数据的方式，而是执行以下操作

  foreach (var softwareProductid in softwareProductIds)
           {
               var matric = new BuildMetrics();
               matric.SP = bitDB.software_products.Where(x => x.id == softwareProductid).Select(x => x.software_product).FirstOrDefault();
               matric.LatestBuild = bitDB.software_product_builds.Where(x => x.software_product_build_id == softwareProductid).Select(x => x.software_product_build).FirstOrDefault();
               matric.AnnouncedDate = bitDB.software_product_builds.Where(x => x.software_product_build_id == softwareProductid).Select(x => x.date_announced).FirstOrDefault();
               softwareBuildMetrics.Add(matric);

            }

因为

List softwareBuildMetrics=newlist（）
表示BuildMetrics
对象的列表，这就是为什么我在上面的代码中创建了BuildMetrics
的新对象
var matric = new BuildMetrics();

最后，我用softwareBuildMetrics.Add（matric）将这个对象添加到列表中
编辑
您可以使用orderbydecenting
获取最新版本
softwareBuildMetrics.LatestBuild = bitDB.software_product_builds.Where(x => x.software_product_build_id == softwareProductid).OrderByDescending(x => x.date_announced).Select(x => x.software_product_build).FirstOrDefault();

您有以下代码行：
List<BuildMetrics> softwareBuildMetrics = new List<BuildMetrics>(); 

你在使用什么样的类库？你说这些类库是什么意思？BuildMetrics
是Api模型类，现在我正试图编写一个从数据库检索datea的方法来填充类的属性？你有这行代码：List softwareBuildMetrics=new List（）这是BuildMetrics
的通用列表。列表
类型没有SP
、LatestBuild
和AnnouncedDate
属性，因此您会得到该错误。如何根据软件产品构建表中公布日期（格式为2016-12-02 19:24:32）中的时间戳获取最新构建？您是指最后一个构建？或特定构建？上次构建还是最新构建？数据库有一个列date_公布，该列有创建的时间戳…需要使用它来确定哪一个是最后一个（最新的）buildyou现在可以检查了。我的最后一个问题是，当我返回新度量值时，出现以下错误ierror 3无法将类型“Dashboard.Model.ApiModels.BuildMetrics”隐式转换为“System.Collections.Generic.IEnumerable”‌. 存在显式转换（是否缺少转换？
，如何转换？编码Yoshi-当我返回新度量值时，出现错误错误3无法将类型“Dashboard.Model.ApiModels.BuildMetrics”隐式转换为“System.Collections.Generic.IEnumerable”。存在显式转换（是否缺少转换？
，如何转换？您需要返回softwareBuildMetrics
而不是newMetric。请参见编辑。
var newMetric = null;
foreach (var softwareProductid in softwareProductIds)
{
    newMetric = new BuildMetrics();
    newMetric.SP = bitDB.software_products.Where(x => x.id == softwareProductid).Select(x => x.software_product).FirstOrDefault();
    newMetric.LatestBuild = bitDB.software_product_builds.Where(x => x.software_product_build_id == softwareProductid).Select(x => x.software_product_build).FirstOrDefault();
    newMetric.AnnouncedDate = bitDB.software_product_builds.Where(x => x.software_product_build_id == softwareProductid).Select(x => x.date_announced).FirstOrDefault();

    softwareBuildMetrics.Add(newMetric);
}

return softwareBuildMetrics;