Linq To SQL DRY

Question

我们决定在最近的项目中使用Linq to SQL作为数据层。我们有一个功能解决方案，到目前为止，它已经处理了我们在它上面抛出的所有东西，但有一个主要问题。我们必须一遍又一遍地编写相同的方法，以便从数据库中检索略有不同的结果集。

举个例子：

        public List<TeamBE> GetTeamsBySolutionID(Guid SolutionID)
        {
            List<TeamBE> teams = new List<TeamBE>();

            Esadmin db = new Esadmin(_connectionString);

            var qry = (from teamsTable in db.Teams
                       join solutionsTable in db.Solutions on teamsTable.SolutionID equals solutionsTable.SolutionID
                       where teamsTable.SolutionID == SolutionID
                       select new { teamsTable, solutionsTable.SolutionName });

            foreach (var result in qry)
            {
                TeamBE team = new TeamBE();

                team.TeamID = result.teamsTable.TeamID;
                team.Description = result.teamsTable.Description;
                team.Status = result.teamsTable.Status;
                team.LastModified = result.teamsTable.LastModified;
                team.SolutionID = result.teamsTable.SolutionID;
                team.SolutionName = result.SolutionName;
                team.Name = result.teamsTable.Name;
                team.LocationLevel = result.teamsTable.LocationLevel;
                team.AORDriven = result.teamsTable.AoRDriven;
                team.CriteriaID = result.teamsTable.CriteriaID ?? Guid.Empty;

                teams.Add(team);
            }
            return teams;
        }

        public TeamBE GetTeamByID(Guid TeamID)
        {
            Esadmin db = new Esadmin(_connectionString);
            TeamBE team = new TeamBE();

            var qry = (from teamsTable in db.Teams
                       join solutionsTable in db.Solutions on teamsTable.SolutionID equals solutionsTable.SolutionID
                       where teamsTable.TeamID == TeamID
                       select new { teamsTable, solutionsTable.SolutionName }).Single();

            team.TeamID = qry.teamsTable.TeamID;
            team.Description = qry.teamsTable.Description;
            team.Status = qry.teamsTable.Status;
            team.LastModified = qry.teamsTable.LastModified;
            team.SolutionID = qry.teamsTable.SolutionID;
            team.SolutionName = qry.SolutionName;
            team.Name = qry.teamsTable.Name;
            team.LocationLevel = qry.teamsTable.LocationLevel;
            team.AORDriven = qry.teamsTable.AoRDriven;
            team.CriteriaID = qry.teamsTable.CriteriaID ?? Guid.Empty;

            return team;
        }

不计其数的。

有没有一种方法可以将Linq结果作为参数传递给函数，这样我就可以将对象映射放在一个函数中，而不需要重复这么多？

Answer 1

我很快就试了一下。可能不会编译(尤其是"from teamsTalbe in teams“)，但是你可以分解出返回IQueryable<>的东西。虽然你的IQueryable返回了一个匿名类型，但这不会起作用。所以你可能需要创建一个显式类型来代替”select new { teamsTable，solutionsTable.SolutionName }“。

    public List<TeamBE> GetTeamsBySolutionID(int solutionID)
    {
        Esadmin db = new Esadmin(_connectionString);
        return GetTeamsBy(db, _GetTeamsBySolutionID(db, solutionID));
    }

    IQueryable<Team> _GetTeamsBySolutionID(Esadmin db, int solutionID)
    {
        return from teamsTable in db.Teams
               where teamsTable.SolutionID == SolutionID
               select teamsTable;
    }

    List<TeamBE> GetTeamsBy(Esadmin db, IQueryable<Team> teams)
    {
        List<TeamBE> teams = new List<TeamBE>();

        var qry = (from teamsTable in teams
                   join solutionsTable in db.Solutions on teamsTable.SolutionID equals solutionsTable.SolutionID
                   select new { teamsTable, solutionsTable.SolutionName });

        foreach (var result in qry)
        {
            TeamBE team = new TeamBE();

            team.TeamID = result.teamsTable.TeamID;
            team.Description = result.teamsTable.Description;
            team.Status = result.teamsTable.Status;
            team.LastModified = result.teamsTable.LastModified;
            team.SolutionID = result.teamsTable.SolutionID;
            team.SolutionName = result.SolutionName;
            team.Name = result.teamsTable.Name;
            team.LocationLevel = result.teamsTable.LocationLevel;
            team.AORDriven = result.teamsTable.AoRDriven;
            team.CriteriaID = result.teamsTable.CriteriaID ?? Guid.Empty;

            teams.Add(team);
        }
        return teams;
    }

Answer 2

我认为您可以将qry变量声明为IEnumerable<YourDataTypeEntity>并将其传递给一个方法。我倾向于将其作为一个构造函数来做：

class MyDataType
{
  public MyDataType() {}
  public MyDataType(MyDataTypeEntity mdte)
  {
    // set properties and fields here
  }

  // ...
}

Answer 3

你可以传递一个IQueryable，然后当你想要处理结果时，你可以迭代结果。我不确定这是你问的那种问题，还是我离你的问题太远了。