实体框架主动加载不工作

本文关键字:工作 加载 框架 实体 | 更新日期: 2023-09-27 18:03:31

我想从数据库使用实体框架6和急于加载对象列表。但是实体框架使用延迟加载。我使用了SQL分析器,并且在访问引用子实体的属性时执行查询。通过使用'Include',你应该一次加载相关实体,但它没有发生。我的代码如下:

    using (var flightsPricingRulesContext = new FlightsPricingRulesDbContext())
    {
       flightsPricingRulesContext.Configuration.ValidateOnSaveEnabled = false;
       flightsPricingRulesContext.Configuration.AutoDetectChangesEnabled = false;

   var filter = PredicateBuilder.True<FlightsPricingRulesDataAccess.Models.ServiceFee>();
    if (!String.IsNullOrEmpty(selectedMarketId))
    {
       var selectedMarket = Int32.Parse(selectedMarketId);
       filter = filter.And(sf => sf.MarketId == selectedMarket);
    }
    if (!String.IsNullOrEmpty(selectedApplicationTypeId))
    {
       var selectedAppplicationType = Int32.Parse(selectedApplicationTypeId);
       filter = filter.And(sf => sf.ApplicationType == selectedAppplicationType);
    }
    var Query = 
    from P in flightsPricingRulesContext.ServiceFee.AsExpandable().Where(filter)select P;
    switch (orderby)
    {
      case null:
      case "":
      case "Id":
      Query = String.IsNullOrEmpty(orderbydirection) || orderbydirection  == "ASC"
      ?Query.OrderBy(p => p.Id): Query.OrderByDescending(p => p.Id);
      break;
      case "market":
      Query = String.IsNullOrEmpty(orderbydirection) || orderbydirection == "ASC"
      ? Query.OrderBy(p => p.MarketId)
      : Query.OrderByDescending(p => p.MarketId);
      break;
    }
    var takeitems = 10 ;
    var skipitems = (Int32.Parse(page) - 1) * 10);
    //BY USING INCLUDE EAGER LOADING IS ENABLED
    Query = Query.Skip(skipitems).Take(takeitems).
    Include(sf => sf.ServiceFeeZone.Select(sfz => sfz.Zone)).
    Include(sf => sf.ServiceFeeCarrier).
    Include(sf => sf.ServiceFeeClassOfService).
    Include(sf => sf.ServiceFeeDate).
    Include(sf => sf.ServiceFeeMarkUpAssignment).
    Include(sf => sf.ServiceFeeAssignment);
    var results = Query.ToList();//HERE A COMPLETE QUERY SHOULD BE 
    //SENT TO THE DB FOR RETRIEVING ENTITES INCLUDING THEIR CHILDREN
    var totalresults = flightsPricingRulesContext.ServiceFee.AsExpandable().Count(filter);
    var pagedservicefees = new PagedServiceFee();
    pagedservicefees.totalitems = totalresults.ToString();
    pagedservicefees.servicefees = new List<FlightsPricingRules.Models.ServiceFee>();

    foreach (var servicefeedto in results)
    {
       var servicefee = new FlightsPricingRules.Models.ServiceFee();
       servicefee.id = servicefeedto.Id.ToString();
       servicefee.marketId = servicefeedto.MarketId.ToString();
        //.....
        //SOME MORE PROPERTIES
        //                      
    //CHILD ENTITIES
        //Zones
        servicefee.zones = new List<Zone>();
        //HERE AN   ADDITIONAL QUERY IS MADE TO LOAD THE CHILD ENTITIES-WHY?
        foreach (var zonedto in servicefeedto.ServiceFeeZone)
        {
           var zone = new Zone();
           zone.id = zonedto.ZoneId.ToString();
           zone.name = zonedto.Zone.Name;
           servicefee.zones.Add(zone);
         }
          //Carriers
          servicefee.carriers = new List<Carr>();
          //ALSO HERE AND ADDITIONAL QUERY IS MADE
          foreach (var carrierdto in servicefeedto.ServiceFeeCarrier)
          {
            var carrier = new Carr();
            carrier.id = carrierdto.AirlineId.ToString();
            servicefee.carriers.Add(carrier);
           }

      pagedservicefees.servicefees.Add(servicefee);
   }
   //.......
   //SOME MORE CHILD ENTITIES
   //

return Json(pagedservicefees, JsonRequestBehavior.DenyGet);
}                

实体框架主动加载不工作

好了,我明白了。事实证明,放置Include语句的位置很重要。我将Include语句放在. asexpandable()之前和父实体之后,现在执行即时加载。我还可以用SQL分析器验证,查询包含所有必要的连接,并且执行得非常快。正确的查询现在是:

var Query = from P in flightsPricingRulesContext.ServiceFee
.Include(sf =>   sf.ServiceFeeCarrier)
.Include(sf=>sf.ServiceFeeAssignment)
.Include(sf => sf.ServiceFeeClassOfService)
.Include(sf => sf.ServiceFeeDate)
.Include(sf => sf.ServiceFeeMarkUpAssignment)
.Include(sf => sf.ServiceFeeZone.Select(zo => zo.Zone))
.AsExpandable().Where(filter) select P;

张贴答案,以防有人遇到同样的情况