Entity Framework left join on multiple tables creates inner join instead

Question

I'm trying to create a query that joins four tables together, only one of which is guaranteed to exist. I've been successful creating left joins in EF before, but never with more than one join. Here is the query:

   var details = (from planInfo in context.PlanInfo
                 join templateRec in context.ProductTemplates
                    on planInfo.TemplateId equals templateRec.TemplateId into templateGroup
                 from template in templateGroup.DefaultIfEmpty()
                 join profileRec in context.CustomerProfiles
                    on planInfo.ProfileId equals profileRec.ProfileId into profileGroup
                 from profile in profileGroup.DefaultIfEmpty()
                 join territoryRec in context.Territories
                    on planInfo.TerritoryId equals territoryRec.TerritoryId into territoryGroup
                 from territory in territoryGroup.DefaultIfEmpty()
                 where planInfo.ActiveStatus
                 && planInfo.PlanId == plan.PlanId
                 select new
                 {
                    PlanId = planInfo.PlanId,
                    TemplateId = planInfo.TemplateId,
                    TemplateGridId = planInfo.TemplateId,
                    ProfileRec = (profile == null ?
                    new
                    {
                       ProfileId = 0,
                       ProfileGridId = 0,
                       Description = string.Empty
                    } :
                    new
                    {
                       ProfileId = profile.ProfileId,
                       ProfileGridId = profile.ProfileId,
                       Description = profile.Description
                    }),
                    ProfileId = (profile == null ? 0 : profile.ProfileId),
                    TerritoryRec = (territory == null ?
                    new
                    {
                       TerritoryId = 0,
                       TerritoryGridId = 0,
                       Description = string.Empty
                    } :
                    new
                    {
                       TerritoryId = territory.TerritoryId,
                       TerritoryGridId = territory.TerritoryId,
                       Description = territory.Description
                    }),
                    TerritoryId = (territory == null ? 0 : territory.TerritoryId),
                    Description = (template == null ? string.Empty: template.Description),
                    TemplateEffectiveDate = planInfo.TemplateEffectiveDate,
                    TemplateExpiryDate = planInfo.TemplateExpiryDate,
                    MinVolume = planInfo.MinVolume,
                    MaxVolume = planInfo.MaxVolume,
                    AccrualPercent = planInfo.AccrualPercent,
                    AccrualPercentNatl = planInfo.AccrualPercentNatl,
                    EffectiveDate = planInfo.EffectiveDate,
                    ExpiryDate = planInfo.ExpiryDate
                 }).ToList();

And here is the SQL that it generates. No matter what I seem to do, I always get several INNER JOIN followed by LEFT JOIN, when what I want is all LEFT JOIN.

SELECT 
    [Filter1].[PlanId] AS [PlanId], 
    [Filter1].[TemplateId1] AS [TemplateId], 
    [Filter1].[ProfileId1] AS [ProfileId], 
    [Filter1].[Description1] AS [Description], 
    CASE WHEN ([Extent4].[TerritoryId] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C1], 
    [Extent4].[TerritoryId] AS [TerritoryId], 
    [Extent4].[Description] AS [Description1], 
    CASE WHEN ([Extent4].[TerritoryId] IS NULL) THEN 0 ELSE [Extent4].[TerritoryId] END AS [C2], 
    [Filter1].[Description2] AS [Description2], 
    [Filter1].[TemplateEffectiveDate] AS [TemplateEffectiveDate], 
    [Filter1].[TemplateExpiryDate] AS [TemplateExpiryDate], 
    [Filter1].[MinVolume] AS [MinVolume], 
    [Filter1].[MaxVolume] AS [MaxVolume], 
    [Filter1].[AccrualPercent] AS [AccrualPercent], 
    [Filter1].[AccrualPercentNatl] AS [AccrualPercentNatl], 
    [Filter1].[EffectiveDate] AS [EffectiveDate], 
    [Filter1].[ExpiryDate] AS [ExpiryDate]
    FROM   (SELECT [Extent1].[PlanId] AS [PlanId], [Extent1].[TemplateId] AS [TemplateId1], [Extent1].[TerritoryId] AS [TerritoryId], [Extent1].[TemplateEffectiveDate] AS [TemplateEffectiveDate], [Extent1].[TemplateExpiryDate] AS [TemplateExpiryDate], [Extent1].[MinVolume] AS [MinVolume], [Extent1].[MaxVolume] AS [MaxVolume], [Extent1].[AccrualPercent] AS [AccrualPercent], [Extent1].[AccrualPercentNatl] AS [AccrualPercentNatl], [Extent1].[EffectiveDate] AS [EffectiveDate], [Extent1].[ExpiryDate] AS [ExpiryDate], [Extent2].[Description] AS [Description2], [Extent3].[ProfileId] AS [ProfileId1], [Extent3].[Description] AS [Description1]
        FROM   [dbo].[PlanInfo] AS [Extent1]
        INNER JOIN [dbo].[ProductTemplates] AS [Extent2] ON [Extent1].[TemplateId] = [Extent2].[TemplateId]
        INNER JOIN [dbo].[CustomerProfiles] AS [Extent3] ON [Extent1].[ProfileId] = [Extent3].[ProfileId]
        WHERE [Extent1].[ActiveStatus] = 1 ) AS [Filter1]
    LEFT OUTER JOIN [dbo].[Territories] AS [Extent4] ON [Filter1].[TerritoryId] = [Extent4].[TerritoryId]
    WHERE [Filter1].[PlanId] = '12345'

Hoping someone can point out what I'm doing wrong here. Thanks!

Answer 1

The INNER JOINS represent required n:1 associations. If you had navigation properties, the join would be a reference to another, required, entity, not a collection. EF knows from the data model that an OUTER JOIN would have no effect here, so it generates an INNER JOIN.