Entity Framework Developers Want GroupBy, Lazy Loading, More

Somewhat lost among all the big "version 2.0" product releases last week was the new Entity Framework Core 2.0.

The open source object-relational mapping (ORM) framework for ADO.NET is now targeting the new .NET Standard 2.0 for consistent API usage across all .NET implementations, along with improved LINQ translation, a Like query operator and many more improvements.

Those enhancements and many more can be seen in EF's "what's new" post.

However, some developers are clamoring for new features that didn't make it into EF 2.0. Judging from user comments, high on that list are GroupBy functionality and lazy loading.

"Any idea when GroupBy translation support and lazy loading will make it in? Those are the major blockers for us," said the first comment to last week's announcement post.

Among dozens of other posts, several other users chimed in, with comments like:

• "I agree, it doesn't make sense to use EF Core 2.0 without GroupBy support."
• "Group by is a must have! EF Core is useless for us at the moment without support for real group by. Grouping at the client is a no-go for real database applications (at least for the kind of applications we write -- Line of Business apps)."
• "Can you please, share information when are these supposed to be available? Lazy loading, group by?"
• "Seems like EF Core is limited to relatively simple applications and data models until it can handle that [table per type] and Group by."
• "I need lazy load, when will it launch?"
• "Keep it up! I suspect adoption will increase massively with lazy loading."

Over at the Reddit social coding site, the lazy loading question was also addressed, implying such support is coming in the next version:

Q: Still no lazy loading of navigation properties...? Isn't that one of the main features of EF? Confused why it wasn't implemented in 1.0.

A: There has been discussion about lazy loading being an antipattern but more than anything the implementation in EF6 was not optimal (or not used correctly) so it has been held back while thoughtfully evaluated. Looks like there's been a recent update on this and it's been tagged for EF Core 2.1

Noted EF expert Julie Lerman is also no big fan of lazy loading and has discouraged users from using it. See below for her comments on that issue and others.

Meanwhile, Microsoft's Diego B Vega, program manager on the EF team, confirmed that lazy loading and GroupBy functionality were targeted for version 2.1.

"Both features are in the 2.1 plan, although lazy loading is a 'stretch goal,' meaning that we will do our best to get to it," Vega said.

While GroupBy functionality and lazy loading figured prominently in Vega's commentary posts, a post related to that latter issue also heads the "most commented" list on the official GitHub site for tracking feature requests, bugs and other feedback.

A 2015 item, "Lazy Loading of navigation properties," received 150 comments. The request starts out with: "I was wondering if I am the only one that thinks EF7 is useless without Lazy Loading? Or do I do something wrong?"

However, no "GroupBy" related requests seem to be high in the most-commented rankings. The GitHub method for tracking feature requests doesn't have the same drill-down capabilities of Microsoft's UserVoice mechanism for tracking Visual Studio feedback.

I reached out to Julie Lerman, one of the top EF development experts, for her take on the user requests.

"There are two types of features that people are clamoring for," Lerman said. "One is features that early versions of EF never had that they've always wanted. We've already gotten lots of those since EF Core's new code base gave the team a new path for enabling these features. The other is things people were used to and dependent on from EF6 (and important for any ORM) such as lazy loading, the GroupBy support and TPT inheritance."

Table per Type (TPT), Vega said, is still a request in backlog, and he invited developers to vote up the issue on GitHub.

Here are Lerman's observations on the other two issues mentioned above:

"GroupBy is a tricky topic," she said. "The people who need it really need it. As far as I know, the path for the EF Team to build it in was depending on another feature that they are working on. I believe that the delay on GroupBy is a combination of things: 1) the 'bang for the buck' with respect to how much work it is for them to implement vs/ the impact it will have compared to the many other features they have been working through on the very long list and 2) the fact that there IS a workaround which is to write custom SQL."

"LazyLoading is something that I have never used and have actively discouraged people from using because I've seen too many teams encountering performance problems when they were not aware of lazy loading's side effects," Lerman continued. "Learning best practices will solve that but it's just too easy to use without knowing how it really works. Since it's easy enough to load related data explicitly after the fact, I think this feature has been overridden by more pressing features that don't have easy alternatives."

EF chief Vega said the framework's roadmap is still being updated for version 2.1 and future releases, but to get an idea of prioritized issues being worked on now, he pointed developers to this GitHub query that sorts issues by 2.1 milestones concerning enhancements.

On that list, the top five most-commented issues include lazy loading and GroupBy functionality:

• Lazy Loading of navigation properties
• Seed Data
• Column ordering
• Relational: Support translating GroupBy() to SQL
• Support for custom type mapping and data store to CLR type conversions

Posted by David Ramel on 08/21/2017