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POCustom Explicit Loading in Entity Framework - any way to do it?
 

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    <p>I've got a list of entity object Individual for an employee survey app - an Individual represents an employee or outside rater. The individual has the parent objects Team and Team.Organization, and the child objects Surveys, Surveys.Responses. Responses, in turn, are related to Questions.</p> <p>So usually, when I want to check the complete information about an Individual, I need to fetch Individuals.Include(Team.Organization).Include(Surveys.Responses.Question).</p> <p>That's obviously a lot of includes, and has a performance cost, so when I fetch a list of Individuals and don't need their related objects, I don't bother with the Includes... but then the user wants to manipulate an Individual. So here's the challenge. I seem to have 3 options, all bad:</p> <p>1) Modify the query that downloads the big list of Individuals to .Include(Team.Organization).Include(Surveys.Responses.Question). This gives it bad performance.</p> <p>2) Individuals.Load(), TeamReference.Load(), OrganizationReference.Load(), Surveys.Load(), (and iterate through the list of Surveys and load their Responses and the Responses' Questions).</p> <p>3) When a user wishes to manipulate an Individual, I drop that reference and fetch a whole brand new Individual from the database by its primary key. This works, but is ugly because it means I have two different kinds of Individuals, and I can never use one in place of the other. It also creates ugly problems if I'm iterating across a list repeatedly, as it's tricky to avoid loading and dropping the fully-included Individuals repeatedly, which is wasteful.</p> <p>Is there any way to say </p> <pre><code>myIndividual.Include("Team.Organization").Include("Surveys.Responses.Question"); </code></pre> <p>with an existing Individual entity, instead of taking approach (3)?</p> <p>That is, is there any middle-ground between "fetch everything from the database up-front" and "late-load one relationship at a time"?</p> <p>Possible solution that I'm hoping I could get insight about:</p> <p>So there's no way to do a manually-implemented explicit load on a navigational-property? No way to have the system interpret</p> <pre><code>Individual.Surveys = from survey in MyEntities.Surveys.Include("Responses.Question") where survey.IndividualID = Individual.ID select survey; //Individual.Surveys is the navigation collection property holding Surveys on the Individual. Individual.Team = from team in MyEntities.Teams.Include("Organization") where team.ID = Individual.TeamID select team; </code></pre> <p>as just loading Individual's related objects from the database instead of being an assignment/update operation? If this means no actual change in X and Y, can I just do that?</p> <p>I want a way to manually implement a lazy or explicit load that isn't doing it a dumb (one relation at a time) way. Really, the Teams and Organizationss aren't the problem, but the Survey.Responses.Questions are a massive buttload of database hits.</p> <p>I'm using 3.5, but for the sake of others (and when my project finally migrates to 4) I'm sure responses relevant to 4 would be appreciated. In that context, similar customization of lazy loading would be good to hear about too.</p> <p>edit: Switched the alphabet soup to my problem domain, edited for clarity.</p> <p>Thanks</p>
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    1. COUsually its better to use a hypothetical model than alphabet soup. I have no idea whats going on. ;)
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    2. COAgreed. Please re-word this question, preferably with a screenshot of your EDMX. This is around 10 paragraphs of cryptic language. Be more precise please.
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    3. COEdited for clarity. I'm never comfortable dumping the whole client's data model online (or any massive pile of customer code), so I didn't dump the EDMX, but I think it's clearer this way.
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