CODEWITHSUNDEEP
c#entity-frameworkef-code-first
Usman
Usman

Reputation: 51

Override NotMapped attribute in derived class

I'm working on an EF Code-First based application. I have a base class inherited by dozens of classes, each representing entities in database. The base class has a property with [NotMapped] attribute, that was originally required to be [NotMapped] for all derived classes as well.

public class BaseEntity
{
    [NotMapped]
    public string Message { get; set; }
}

I've come across an entity having column name exactly as that property name, but just due to inheriting [NotMapped] attribute from the parent, the value doesn't get stored in database.

public class InheritedEntity : BaseEntity
{
    public string Message { get; set; } // This is what I want mapped
}

Is there any way to override the NotMapped behaviour just for that class, either through DataAnnotations or FluentAPI? I've tried setting [Column()] but it doesn't work.

Upvotes: 2

Views: 1349

Answers (1)

h3n
h3n

Reputation: 5248

You need to create a new attribute that does what NotMapped do.

NotMappedPropertyAttributeConvention
Applies the ff to your modelBuilder configuration: 
ConventionTypeConfiguration Ignore(PropertyInfo propertyInfo)

First, create custom attribute.


public class CustomNotMappedAttribute : Attribute
{
    public CustomNotMappedAttribute()
    {
        this.Ignore = true;
    }
    public bool Ignore { get; set; }
}

Then, create a PropertyAttributeConvention


public class CustomNotMappedPropertyAttributeConvention : PropertyAttributeConfigurationConvention
{
    public override void Apply(PropertyInfo memberInfo, ConventionTypeConfiguration configuration, CustomNotMappedAttribute attribute)
    {
        if (attribute.Ignore)
        {
            configuration.Ignore(memberInfo);
        }
    }
}

Then, add it to the configuration conventions


protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Conventions.Add(new CustomNotMappedPropertyAttributeConvention());
}

Your property in entitybase should be decorated with:

[CustomNotMapped]
instead of 
[NotMapped]

public class BaseEntity
{
    [CustomNotMapped]
    public virtual string Message { get; set; }
}

public class InheritedEntity : BaseEntity
{
    [CustomNotMapped(Ignore = false)]
    public override string Message { get; set; }
}

There you go. Your message property in your BaseEntity will be ignore except to those decorated with [CustomNotMapped(Ignore = false)]

Upvotes: 2

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