Owned type cannot be specified in owner entity's parameterised ctor

[lonix1]

The owned types page explains how to use value objects. The constructors page explains how to use parameterised ctors. But there is no mentioned of how to do that together.

public sealed class Foo
{
    public string Something { get; private set; }
    public Bar Bar { get; private set; }     // owned type

    public Foo(string something, Bar bar)                  // won't work
    {
        Something = something;
        Bar = bar;
    }
}

EF will throw an exception due to that ctor. That is because Bar is an owned type, and it is treated as a navigation property.

To make this work we must remove Bar from the ctor. EF will then run the ctor, and then populate the property separately.

The page should also explicitly mention

Owned types are treated as navigation properties

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Document Details

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• ID: d02e6748-42e0-000a-4945-42cd05a0b875
• Version Independent ID: e3effbd0-07f2-423d-4032-1722e75adb37
• Content: Owned Entity Types - EF Core
• Content Source: entity-framework/core/modeling/owned-entities.md
• Product: entity-framework
• Technology: entity-framework-core
• GitHub Login: @AndriySvyryd
• Microsoft Alias: avickers

[ajcvickers]

Covered by #1627.

See also dotnet/efcore#26398, which changed the message in EF7 to something like this:

No suitable constructor was found for entity type 'BlogNone'. The following constructors had parameters that could not be bound to properties of the entity type: cannot bind 'did' in 'BlogNone(string title, int did)'; cannot bind 'notTitle' in 'BlogNone(string notTitle, Guid? shadow, int id)'; cannot bind 'dummy' in 'BlogNone(string title, Guid? shadow, bool dummy, int id)'; cannot bind 'dummy', 'description' in 'BlogNone(string title, Guid? shadow, bool dummy, int id, string description)'. Note that only mapped properties can be bound to constructor parameters. Navigations to related entities, including references to owned types, cannot be bound.

[lonix1]

Looks good, I'm sure it'll help others who stumble over that.