LINQ to Entities查询未投影子集合

Question

What would cause this query. To start only projecting c without populating its child collection ParcelValues .

var result = (from c in _context.Parcels.Include("ParcelValues")
where c.STRAP == strap
select c);

I was running my app and the above would return a result object of type IQueryable<Parcel> with the property Request.ParcelValues populated with the correct records. Now, for some reason, no matter how I try to use the include, only the Parcel fields are projected.

GENERATED SQL

exec sp_executesql N'SELECT 
[Project2].[LAND_AREA] AS [LAND_AREA], 
[Project2].[STRAP] AS [STRAP], 
[Project2].[SITUS] AS [SITUS], 
[Project2].[ZIP_CODE] AS [ZIP_CODE], 
[Project2].[MAILING_ADDRESS] AS [MAILING_ADDRESS], 
[Project2].[PROPERTY_USE] AS [PROPERTY_USE], 
[Project2].[SUBDIVISION] AS [SUBDIVISION], 
[Project2].[DSCR] AS [DSCR], 
[Project2].[INCORPORATION] AS [INCORPORATION], 
[Project2].[SEC_TWP_RGE] AS [SEC_TWP_RGE], 
[Project2].[CENSUS] AS [CENSUS], 
[Project2].[WATERFRONT] AS [WATERFRONT], 
[Project2].[C1] AS [C1], 
[Project2].[ID] AS [ID], 
[Project2].[STRAP1] AS [STRAP1], 
[Project2].[YEAR] AS [YEAR], 
[Project2].[LAND] AS [LAND], 
[Project2].[IMPROVEMENT] AS [IMPROVEMENT], 
[Project2].[JUST] AS [JUST], 
[Project2].[ASSESSED] AS [ASSESSED], 
[Project2].[TAXABLE] AS [TAXABLE]
FROM ( SELECT 
    [Limit1].[STRAP] AS [STRAP], 
    [Limit1].[SITUS] AS [SITUS], 
    [Limit1].[ZIP_CODE] AS [ZIP_CODE], 
    [Limit1].[MAILING_ADDRESS] AS [MAILING_ADDRESS], 
    [Limit1].[PROPERTY_USE] AS [PROPERTY_USE], 
    [Limit1].[SUBDIVISION] AS [SUBDIVISION], 
    [Limit1].[DSCR] AS [DSCR], 
    [Limit1].[LAND_AREA] AS [LAND_AREA], 
    [Limit1].[INCORPORATION] AS [INCORPORATION], 
    [Limit1].[SEC_TWP_RGE] AS [SEC_TWP_RGE], 
    [Limit1].[CENSUS] AS [CENSUS], 
    [Limit1].[WATERFRONT] AS [WATERFRONT], 
    [Extent2].[ID] AS [ID], 
    [Extent2].[STRAP] AS [STRAP1], 
    [Extent2].[YEAR] AS [YEAR], 
    [Extent2].[LAND] AS [LAND], 
    [Extent2].[IMPROVEMENT] AS [IMPROVEMENT], 
    [Extent2].[JUST] AS [JUST], 
    [Extent2].[ASSESSED] AS [ASSESSED], 
    [Extent2].[TAXABLE] AS [TAXABLE], 
    CASE WHEN ([Extent2].[ID] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C1]
    FROM   (SELECT TOP (1) 
        [Extent1].[STRAP] AS [STRAP], 
        [Extent1].[SITUS] AS [SITUS], 
        [Extent1].[ZIP_CODE] AS [ZIP_CODE], 
        [Extent1].[MAILING_ADDRESS] AS [MAILING_ADDRESS], 
        [Extent1].[PROPERTY_USE] AS [PROPERTY_USE], 
        [Extent1].[SUBDIVISION] AS [SUBDIVISION], 
        [Extent1].[DSCR] AS [DSCR], 
        [Extent1].[LAND_AREA] AS [LAND_AREA], 
        [Extent1].[INCORPORATION] AS [INCORPORATION], 
        [Extent1].[SEC_TWP_RGE] AS [SEC_TWP_RGE], 
        [Extent1].[CENSUS] AS [CENSUS], 
        [Extent1].[WATERFRONT] AS [WATERFRONT]
        FROM [dbo].[PARCELS] AS [Extent1]
        WHERE [Extent1].[STRAP] = @p__linq__0 ) AS [Limit1]
    LEFT OUTER JOIN [dbo].[PARCEL_VALUES] AS [Extent2] ON [Limit1].[STRAP] = [Extent2].[STRAP]
)  AS [Project2]
ORDER BY [Project2].[STRAP] ASC, [Project2].[C1] ASC',N'@p__linq__0 nvarchar(4000)',@p__linq__0=N'0001020003'

Answer 1

KNOW THY DATA

So, it ended up that my whole problem was being caused by a known design feature/bug of the Entity Framework (depending on how you look at it) and my data. I was importing my keys from tables with nchar(25) into my tables with varchar(16) Most tables I was trimming the key before populating my targets. I had forgotten to trim the key on the tables that would never seem to load, except when queried separately. So, it turns out EF can't lazy load related tables with some having trailing whitespace in the keys (whitespace must match too).

Once I updated my script to load all my target sans whitespace. Issue resolved.