Support read-only collections of primitive types

[linkdotnet]

File a bug

With the latest rc1, there is a regression if an object uses a IReadOnlyCollection<string> (or any other primitive type that can be mapped to JSON inside the column). The following code will throw exceptions, that were not existing on preview-7:

using Microsoft.EntityFrameworkCore;

using var context = new MyDbContext();
var allObjects = context.MyObjects.ToArray();

public class MyDbContext : DbContext
{
    public DbSet<MyObject> MyObjects { get; set; }

    public MyDbContext()
    {
        Database.EnsureCreated();
    }
    
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlite("Data Source=MyDatabase.db");
    }
}

public class MyObject
{
    public int Id { get; set; }
    
    public IReadOnlyCollection<string> Tags { get; set; }
}

Stack-Trace:

Unhandled exception. System.ArgumentException: Expression of type 'System.Collections.Generic.IReadOnlyCollection`1[System.String]' cannot be used for parameter of type 'System.Collections.Generic.IList`1[System.String]' of method 'System.Collections.Generic.IList`1[System.String] PopulateList[String](System.Collections.Generic.IList`1[System.String], System.Collections.Generic.IList`1[System.String])' (Parameter 'arg0')
   at System.Dynamic.Utils.ExpressionUtils.ValidateOneArgument(MethodBase method, ExpressionType nodeKind, Expression arguments, ParameterInfo pi, String methodParamName, String argumentParamName, Int32 index)
   at System.Linq.Expressions.Expression.Call(MethodInfo method, Expression arg0, Expression arg1)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityMaterializerSource.<AddInitializeExpressions>g__CreateMemberAssignment|12_0(Expression parameter, MemberInfo memberInfo, IPropertyBase property, Expression value)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityMaterializerSource.AddInitializeExpressions(HashSet`1 properties, ParameterBindingInfo bindingInfo, Expression instanceVariable, List`1 blockExpressions)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityMaterializerSource.CreateMaterializeExpression(List`1 blockExpressions, ParameterExpression instanceVariable, Expression constructorExpression, HashSet`1 properties, ParameterBindingInfo bindingInfo)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityMaterializerSource.CreateMaterializeExpression(EntityMaterializerSourceParameters parameters, Expression materializationContextExpression)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.EntityMaterializerInjectingExpressionVisitor.CreateFullMaterializeExpression(ITypeBase concreteTypeBase, ValueTuple`4 materializeExpressionContext)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.EntityMaterializerInjectingExpressionVisitor.MaterializeEntity(StructuralTypeShaperExpression shaper, ParameterExpression materializationContextVariable, ParameterExpression concreteEntityTypeVariable, ParameterExpression instanceVariable, ParameterExpression entryVariable)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.EntityMaterializerInjectingExpressionVisitor.ProcessEntityShaper(StructuralTypeShaperExpression shaper)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.EntityMaterializerInjectingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.EntityMaterializerInjectingExpressionVisitor.Inject(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.InjectEntityMaterializers(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.ShaperProcessingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.ShaperProcessingExpressionVisitor.ProcessShaper(Expression shaperExpression, RelationalCommandCache& relationalCommandCache, IReadOnlyList`1& readerColumns, LambdaExpression& relatedDataLoaders, Int32& collectionId)
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.VisitShapedQuery(ShapedQueryExpression shapedQueryExpression)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at Microsoft.EntityFrameworkCore.Query.QueryCompilationContext.CreateQueryExecutor[TResult](Expression query)
   at Microsoft.EntityFrameworkCore.Storage.Database.CompileQuery[TResult](Expression query, Boolean async)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore[TResult](IDatabase database, Expression query, IModel model, Boolean async)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass9_0`1.<Execute>b__0()
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery[TResult](Object cacheKey, Func`1 compiler)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute[TResult](Expression query)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.Execute[TResult](Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable`1.GetEnumerator()
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.System.Collections.Generic.IEnumerable<TEntity>.GetEnumerator()
   at System.Collections.Generic.LargeArrayBuilder`1.AddRange(IEnumerable`1 items)
   at System.Collections.Generic.EnumerableHelpers.ToArray[T](IEnumerable`1 source)
   at Program.<Main>$(String[] args) in /Users/stevengiesel/repos/BlogExamples/Repro/Repro/Program.cs:line 6

Include verbose output

The project is using net8.0-rc.1.

C:\Stuff\AllTogetherNow\FiveOh>dotnet ef dbcontext list --verbose
Using project 'C:\Stuff\AllTogetherNow\FiveOh\FiveOh.csproj'.
...
Finding DbContext classes in the project...
Found DbContext 'BlogContext'.
BlogContext

Include provider and version information

EF Core version:
Database provider: Microsoft.EntityFrameworkCore.Sqlite
Target framework:: .NET 8.0
Operating system: MacOS
IDE: -

[roji]

Confirmed that the above is a regression from preview.7 to rc.1.

@ajcvickers @maumar is one of you interested in taking a look? Seems to be materialization-related.

[ajcvickers]

@roji Did you try it on the latest daily build?

[roji]

@ajcvickers yeah, sorry, I should have been clearer - this fails on the latest release/8.0 commit (a4db3b7) with the same exception.

[maumar]

culptit: #31272 EntityMaterializerSource -> CreateMemberAssignment

PopulateList is trying to add elements from buffer to the target, but that's not allowed for read only collections.

[ajcvickers]

I missed this was a read-only collection. We don't support read-only collections in EF 8. We should throw a better exception. (They weren't fully functional in earlier EF8 previews, they just didn't throw.)

[ajcvickers]

See also #25364 when fixing this.

[Atomosk]

I missed this was a read-only collection. We don't support read-only collections in EF 8. We should throw a better exception. (They weren't fully functional in earlier EF8 previews, they just didn't throw.)

But it throws the error even with List<> backing field and EntityTypeBuilder.Property().HasField().UsePropertyAccessMode(PropertyAccessMode.Field). Should't using field access mode make property declaration irrelevant?