Dotnet Core - configuring lazy loading in startup

Question

I asked a question (got a -2 for my efforts but thats besides the point). The only answer indicated I should use lazyloading by adding it in StartUp.cs.

However, no matter what I do I cannot add this. I followed the direction of the link the author suggested as well as what the author did and in all cases I got the following.

Severity Code Description Project File Line Suppression State Error CS1061 'DbContextOptionsBuilder' does not contain a definition for 'UseLazyLoadingProxies' and no accessible extension method 'UseLazyLoadingProxies' accepting a first argument of type 'DbContextOptionsBuilder' could be found (are you missing a using directive or an assembly reference?) JobsLedger.API C:\Users\simon\OneDrive\Documents\1.0 - AURELIA\1.0 - JobsLedgerSPA -ASPNET CORE 3.1\JobsLedger.API\Startup.cs 74 Active

If there is an assembly reference I wonder if someone might point me in the right direction.

This is what I currently have along with the modification as per the link the author for that question suggested.

    services.AddDbContext<CATALOGContext>(options => options.UseSqlServer(_configuration.GetConnectionString("CatalogConnection"), b => b.MigrationsAssembly("JobsLedger.CATALOG")));
    services.AddDbContext<DATAContext>(options => options.UseLazyLoadingProxies().UseSqlServer(_configuration.GetConnectionString("TenantDbConnection"), a => a.MigrationsAssembly("JobsLedger.DATA")));

How do I configure these lines for ".UseLazyLoadingProxies" as its currently saying this is not available?

Have you added the [`Microsoft.EntityFrameworkCore.Proxies`](https://www.nuget.org/packages/Microsoft.EntityFrameworkCore.Proxies/) Nuget package? — DavidG, Feb 20 '20 at 12:48
I hadn't so I did that and I am still not able to get the option. — si2030, Feb 20 '20 at 13:01
I finally got this working as once I added the package mentioned above I needed to change all linked entities so they had the "virtual" name which I did. Thanks DavidG — si2030, Mar 02 '20 at 05:43
@DavidG, great save, do as Jacob Alley suggests and submit as answer, I'll upvote too. — alvinchesaro, Apr 21 '21 at 14:20
@DavidG, ditto on what everyone is saying. Add your comment as an answer — Jacques, May 13 '21 at 15:25

score 8 · Answer 1 · answered Jun 16 '21 at 17:06

8

Per the comments and my own research on this issue, add Microsoft.EntityFrameworkCore.Proxies to your package as it contains the UseLazyLoading method you need to add to your DB Context options.

answered Jun 16 '21 at 17:06

Eric Conklin

539
4
17

Side note - I don't actually recommend using lazy loading. I would prefer explicit loading statements within entity framework core such as .Include() or .Select() to ensure good performance. If you have a small database you can enable lazy loading no problem but larger databases should have explicit loads. – Eric Conklin Jan 27 '23 at 18:52

Dotnet Core - configuring lazy loading in startup

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