How to ignore properties during EDM build

[RuiHou105]

Hi team,

I know that if we want to ignore properties during EDM model building, we can use the format: for example, auditEvents.Ignore(t => t.activity). In this way the property activity is ignored.

But right now, I am working on providing a common method for service teams to ignore their unused properties. So, in my method, the usage can be: generatedObject.Ignore( t => t.propertyName). My question is: since this is a common method, actually I don't know every class's property name, so how can I write the expression in Ignore method? Or is there any other way to ignore properties?

Thanks,
Rui

[commonsensesoftware]

Is there a reason why you could not just have model authors apply [JsonIgnore] (OData 8+) or [IgnoreDataMember] to the properties they want to have excluded? It seems that would solve the problem without having to write any special code on your own.

[RuiHou105]

Hi @commonsensesoftware thanks for your reply! Here My scenario is: firstly, use the API versioning tool to specify which graph version current controller supports. If current supported version is beta, I am going to ignore nothing; if current supported version is V1.0, I am going to ignore some properties in the startup. So here I can't directly add [JsonIgnore] attribute for properties, since beta version won't ignore any properties.

[commonsensesoftware]

There are multiple ways to achieve your result, but you'll likely need to create/expose a facility to teams that you can consume. An attribute or interface are good candidates, but that's not the only way.

Let's say you added the attribute:

[AttributeUsage(AttributeTargets.Property)]
public sealed class InPreviewAttribute : Attribute
{
}

Then clients might apply it as:

public class Person
{
    public int Id { get; set; }
    
    public string FirstName { get; set; }

    public string LastName { get; set; }

    [InPreview]
    public string Email { get; set; }
}

I presume you must be using Reflection to enumerate the properties. A rough skeleton might look like:

var builder = new ODataModelConventionBuilder();
var type = typeof(Person);
var entity = builder.AddEntitySet("People", type).EntityType;
var preview = !string.IsNullOrEmpty(apiVersion.Status);

if (preview)
{
    foreach (var property in type.GetRuntimeProperties())
    {
        if (property.GetCustomAttribute<InPreviewAttribute>() is not null)
        {
            entity.RemoveProperty(property);
        }
    }
}

If you know the clients at build-time, then you can use a source generator instead of Reflection. You could also have the clients implement a particular interface or provide some other method to enable them to filter properties. Avoiding Reflection will improve your startup time.