Fix S6602 FP: "Find" method should not be used for EF Core queries

[pampua84]

This type of suggestion when applied to linq queries that are used by EF Core can lead to throwing exceptions of the type:

System.InvalidOperationException: The LINQ expression 'DbSet().... could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to 'AsEnumerable', 'AsAsyncEnumerable', 'ToList', or 'ToListAsync'. See https://go.microsoft.com/fwlink/?linkid=2101038 for more information.

So this thing should at least be specified in the documentation.

[Tim-Pohlmann]

Hi @pampua84, good catch! Thanks for bringing it to our attention.

[Tim-Pohlmann]

For reference; Similar issues have been resolved for S6605 and S6617: #7286

[sebastien-marichal]

Hello @pampua84,

While the issue has been identified and the fix is in progress, we might miss the case you described.
It would help us a lot if you could provide us with a reproducer illustrating what you described.

Thank you 🙏

[pampua84]

HI @sebastien-marichal,
what exactly should I do? If I can help you I'll gladly do it.

[sebastien-marichal]

If you can provide me a code snippet of the issue you mentioned: using FirstOrDefault in a linq query used by EF Core where S6602 would raise.

Then, I will be able to ensure this case will be covered.

[pampua84]

This is the query where the Find() method (on Properties) cannot be applied as suggested by SonarLint:

var person = _repository.GetData<Person>()
    .Include(p => p.Properties)
    .Where(p => p.Id == id && p.Properties.Find(property => property.Value == "IsGoldMember") != null)
    .Select(p => new Person
    {
        Id = p.Id,
        Name = p.Name,
        Description = p.Description,
        Enabled = p.Enabled,
        Created = p.Created,
        Properties = p.Properties
    });

where repository is:

public abstract class RepositoryBase : IRepository
{
    private readonly DbContext _context;  // EF Core DbContext

    protected RepositoryBase(DbContext context)
    {
        Guard.Against.Null(context);

        _context = context;
    }

    //....

    public IQueryable<TEntity> GetData<TEntity>()
        where TEntity : class
    {
        return _context.Set<TEntity>().AsQueryable();
    }

    //.....

}

[pampua84]

I don't know if only this snippet is good, otherwise if I need a repository with a working application I need more time.

[sebastien-marichal]

Thank you @pampua84!

I am assuming Person.Properties is one of the following types:

• List<T>
• Array
• ImmutableList<T>

If this is the case, I am all good!

[pampua84]

Hi @sebastien-marichal ,
I confirm that the object is a List<T>.