How does EF select a ctor for an entity with multiple ctors?

[lonix1]

When an entity has multiple constructors, EF chooses one according to some undocumented logic.

Suppose an entity has a mix of:

• public parameterless constructor, and
• one or more parameterised constructors,
• of which some are private, protected, public, etc.

...then which constructor will EF choose?

The doc page only states this:

Currently, all constructor binding is by convention. Configuration of specific constructors to use is planned for a future release.

But the CURRENT selection logic is not described.

I understand that in a future release we will be able to specify which ctor to use, but until then, please document the current selection logic, because getting this to work in a large domain is extremely tedious trial-and-error.

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Document Details

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• ID: ecc7aedf-6301-7ec7-4f65-81749b1f54c8
• Version Independent ID: d0774ffa-c841-e6df-72de-d7f53c0d6f6f
• Content: Entity types with constructors - EF Core
• Content Source: entity-framework/core/modeling/constructors.md
• Product: entity-framework
• Technology: entity-framework-core
• GitHub Login: @ajcvickers
• Microsoft Alias: avickers

[lonix1]

I just found this from ajcvickers:

Initial decision: for scalar properties, match zero by default (avoids breaking change) then fewest to most (avoids ignoring field mapping configuration)

Was that a design discussion, or is it the current selection process? And what about access modifiers?

If that is how it works, please consider adding it to that small purple note block I linked to above. Would help many people.

[lonix1]

And until we get an API to deal with this issue, here is a workaround. However it isn't useful in an inheritance hierarchy (due to the static).

[alexanderchr]

For anyone curious, this seems to best the documentation of this behaviour available at the moment:

Trying to find the constructor with the most service properties followed by the least scalar property parameters

https://github.com/dotnet/efcore/blob/master/src/EFCore/Metadata/Internal/ConstructorBindingFactory.cs#L121-124