Mapping to readonly array about mapperly

[github-actions]

🎉 This issue has been resolved in version 2.7.0-next.2 🎉

The release is available on:

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• v2.7.0-next.2

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[latonz]

Thank you for this report. This is definitely something which needs improvement.

[jamescarterbellMSFT]

I was trying to find a stop gap solution for this same exact problem (also doing gRPC mappings) and found the following generate code that seems right, but sadly the parent generator doesn't seem to find the void mapping methods:
private partial void MapToFooBars(List<FooBarModel>? source, RepeatedField<FooBarMessage> target)

Generates:

if (source == null)
    return;
target.Capacity = source.Capacity;
target.this[] = MapToFooBar(source.this[]);

[Blackclaws]

Its similar for dictionaries in generated grpc code. Those are MapFields which also only have a getter. Basically you have to copy the contents from one to the other.

There is a convenience method for this on the MapField however: .Add(IDictionary<string, string>) so in this case I'd expect that the mapper calls this. Is there any way to tell the mapper to deal with a certain field by providing a void method that takes the mapped and to map object?

[jamescarterbellMSFT]

Hoping to open a PR for this asap, but it looks like right now mapperly won't map any readonly properties, but I think it would be fairly safe to default to a model of mapping readonly properties for reference types via existing ref mappers (map(source, target)) and leave open the possibility of doing the same for value types in the future via (map(source, ref target)), which means we may as well do both types using ref. Trying my hand at it to see how complex this is.

[latonz]

Mapperly currently only supports object to object mappings in void mapping methods (thats why the implementation for private partial void MapToFooBars(List<FooBarModel>? source, RepeatedField<FooBarMessage> target) is generated as it is. For such cases the diagnostics should definitely be improved and indexed properties should not be mapped.). Mapperly only generates an implementation for void mapping methods, but does not consider them when looking for / generating a mapping for one type to another.
The main problem here is that Mapperly maps to a property by calling the setter of a property and therefore only takes target properties with an accessible setter into account. As described by @heggi, for collection properties this needs to be adjusted to map to read only collection properties by calling Add/AddRange. Would be very happy to accept any PR implementing this.

[github-actions]

🎉 This issue has been resolved in version 2.7.0 🎉

The release is available on:

• GitHub release
• v2.7.0

Your semantic-release bot 📦🚀