Mapster Mapping Issue: Property Value Turns Null During Adaptation (Value Object)

[TanerSaydam]

Hello Mapster Team,

I encountered an issue while using Mapster to map a Database object. During the mapping process, the UserId property of the Database object is set to null event though it has a value before the adaptation.

Models Involved:

public sealed record Database(
    string Server = "",
    string Name = "",
    string? UserID = null,
    string? Password = null);

public sealed class Company : Entity
{
    public string Name { get; set; } = default!;
    public string ShortName { get; set; } = default!;
    public Database Database { get; set; } = default!;
    public Tax Tax { get; set; } = default!;
    public Address Address { get; set; } = default!;
    public List<Sube>? Subeler { get; set; }
}

public sealed record CompanyUpdateCommand(
    string Id,
    string Name,
    string ShortName,
    Database Database,
    Tax Tax,
    Address Address,
    bool IsActive) : IRequest<Result<string>>;

Mapping Code:

Company? company = await companyRepository.Where(p => p.Id == request.Id)
    .Include(p => p.Subeler)
    .FirstOrDefaultAsync(cancellationToken);

if (company is null)
{
    return Result<string>.Failure("Company not found");
}

request.Adapt(company);
company.Database = request.Database;

Issue:
During the mapping process, the request.DatabaseUserID property has a valid value, but after adaptation, the company.Database.UserId property becomes null. Other properties in the Database object are mapped correctly, but this specific property is not.

Expected Behavior:
The request.Database.UseID value should be property mapped to the company.Database.UserID property without turning null.

Steps Taken:

• Verified that the request.Database.UserID property has a value before the mapping.
• Ensured no custom mapping rules interfere with the mapping process.
• Confirmed that the issue only affects the UserID property.

Could this be a bug or is there a specific configuration required for this scenario? I would appreciate your guidance in resolving this issue.

Thank you! 😊

[andrerav]

Hi @TanerSaydam, could you please try the latest prerelease packages?

[DocSvartz]

Hello @TanerSaydam and @andrerav in mapster 7.40 this error is reproducible.
This is related to the name of the UserID field.

short sample:

public sealed record Database(
string Server = "test-server",
string Name = "Test",
string? Password = null,
string? UserID = null
);


var db = new Database(UserID: "256", Password: "123");
var result = db.Adapt(new Database());
result.UserID.ShouldBe("256"); // is null from default config

Temporary fix:

 TypeAdapterConfig<Database, Database>.NewConfig()
    .Map(dest => dest.UserID, src => src.UserID);

// or 

 TypeAdapterConfig<Database, Database>.NewConfig().NameMatchingStrategy(NameMatchingStrategy.Flexible);

Name of property should not contain "ID" at the beginning or end of the name. (I didn't really check the other cases)

With the code from the development branch it seems to work without fixes. If of course you need such behavior.

[andrerav]

Thank you for clarifying @DocSvartz! :)