Add support for MetadataTypeAttribute

[daniel-white]

System.ComponentModel.DataAnnotations.MetadataTypeAttribute is a handy bridge to attributes defined in other files, especially in code generated files. It works with the validation frameworks. I don't see why it wouldn't here.

Example:

[GeneratedCode]
[MetadataTypeAttribute(typeof(DtoMetadata))]
public partial class Dto
{
    public string Private { get; set; }
}

internal class DtoMetadata
{
     [NotLogged]
     public object Private { get; set; }
}

I think it would be great if both sources could be utilized, but the configuration on the primary class would win in the event of a conflict.

[sungam3r]

What problem do you solve?

[daniel-white]

What problem do you solve?

It solves one case where the properties are defined in a code generated class file. One wouldn’t want to put the attributes in there as they’d get overwritten by the generator

[sungam3r]

ok

[daniel-white]

@nblumhardt is this something you would take a PR for? I'd be happy to start looking how to add this.

I've found this as a potential option: https://stackoverflow.com/questions/17873576/metadata-were-not-loaded-using-metadatatype

[nblumhardt]

Hi @daniel-white - I think so 👍

[daniel-white]

doh. the attribute isn't available in .net standard, so i could add one to the library and reflect on that or just wait till everything is .net 5.

[nblumhardt]

Targeting netcoreapp3.0 or 3.1 would also be fine 👍

[digitalsigi]

I am scaffolding repeatedly a database structure and separated all attributes in a separate file. So I have exactly the same problem.

@nblumhardt May be we can somehow work together to get it done. I am not experienced in multi-targeting, so I would need some help here.

According to Micosoft it sounds to go straight to net5.0.

[digitalsigi]

So was digging a litte deeper into this.

@daniel-white is right, metadatatype comes from Net Framework and is available in net core 3.x but not in net standard.
So I will proceed with net5.0

[SimonCropp]

@digitalsigi are you still interested in submitting a PR for this?

[digitalsigi]

Unfortunately not for the moment. I am still busy with a larger project. Had a quick look into the code, it looks feasable, but its more than just hack an go. If it helps, I could provide some code snippets showing how to dig into attributes hierarchies.

[github-actions]

This issue was marked as stale since it has not been active for a long time

[digitalsigi]

OK, got a ping from github. Here a code snippet I am using to get all properties which are then filtered to select only those with my Custom Attribute:

           var propBaseType = vmType.GetProperties().ToList();
           var metaType = vmType.GetCustomAttributes<MetadataTypeAttribute>(true).ToList().FirstOrDefault();
           var metaProp = new List<PropertyInfo>();
           if (metaType != null)
           {
               var metaClass = metaType.MetadataClassType;
               metaProp = metaClass.GetProperties().ToList();
           }
 
           var propConcat = metaProp.Concat(propBaseType) // Concatenate properties of MetaData class and Base class
                                                          // Take only first -> the one of Metadata, assumed metadata has the avs attribute
                                                          // if base class bears an avs attibute it is silently ignored
                                   .OrderBy(m => m.Name)
                                   ;

I guess something like this has to be added in GetPropertiesRecursive, but I still can't find the time to do it.

[sungam3r]

It definetely can be added. The main thing here is to match attributes from other type to the properties of original type.

[sungam3r]

If someone wants to work on this issue, I will be grateful.

[sungam3r]

I don't think I will work on this feature. Anyone can start up from #91.

[sungam3r]

ping @daniel-white @digitalsigi

[github-actions]

This issue was marked as stale since it has not been active for a long time

[digitalsigi]

Ok folks,

I just synced my fork and I'll have at look at it.

@sungam3r It looks like you are working on something to provide a solution. Whats your status?

[sungam3r]

Nope. See #40 (comment)

[digitalsigi]

Just saw a pending PR. I will hab a look but possibly open a new PR is this OK for you?

[sungam3r]

Yes.