Pagano Posts - Answer Overflow

Pagano

•Created by Pagano on 7/12/2024 in #help

Custom Made Collection

I guess this is a real stupid question but how do I create my own custom collection? I have a Player class and I need to create a custom class that is a Collection of Player with other fields and methods but how do I implement my own collection in .NET Core? If I had to guess, I would say implement IEnumerable<T> and IEnumerator<T> but I don't know how to implement them either. Can I have some help please? I can provide with a more in-depth of the idea and my classes if needed.

103 replies

CC#

•Created by Pagano on 3/19/2024 in #help

Entity Framework Core Issue - Many to Many relationship

I got this error now:

Unable to create a 'DbContext' of type ''. The exception 'The 'Player' property 'PlayerMatch.Player' could not be mapped because the database provider does not support this type. Consider converting the property value to a type supported by the database using a value converter. See https://aka.ms/efcore-docs-value-converters for more information. Alternately, exclude the property from the model using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.' was thrown while attempting to create an instance. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728

Unable to create a 'DbContext' of type ''. The exception 'The 'Player' property 'PlayerMatch.Player' could not be mapped because the database provider does not support this type. Consider converting the property value to a type supported by the database using a value converter. See https://aka.ms/efcore-docs-value-converters for more information. Alternately, exclude the property from the model using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.' was thrown while attempting to create an instance. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728

2 replies

CC#

•Created by Pagano on 3/19/2024 in #help

Beginner in EF Core and SQL Server in need for help

Hello, I am new here but I needed some help using my project. I need to connect to a SQL Server DB using .NET Core with EF Core. This is a simple example of my problem:

internal class UserModel
{
    [Key]
    [Column("ID")]
    [Required]
    public int Id { get; set; }
    [Column("Discord ID")]
    [Required]
    public long DiscordId { get; set; }
    [Column("Discord Name")]
    [Required]
    [MaxLength(32)]
    public required string DiscordName { get; set; }
}

internal class UserModel
{
    [Key]
    [Column("ID")]
    [Required]
    public int Id { get; set; }
    [Column("Discord ID")]
    [Required]
    public long DiscordId { get; set; }
    [Column("Discord Name")]
    [Required]
    [MaxLength(32)]
    public required string DiscordName { get; set; }
}

This would be the table mapped to a C# class, right? However, I need to work with User objects to perform methods and have fields that need to have private setters and getters etc. How would I do that? I was told to user another class like this to wrap around UserModel:

internal class User(UserModel model)
{
    public int Id { get; private set; } = model.Id;
    public long DiscordId { get; private set; } = model.DiscordId;
    public string DiscordName { get; private set; } = model.DiscordName;
        // Methods
}

internal class User(UserModel model)
{
    public int Id { get; private set; } = model.Id;
    public long DiscordId { get; private set; } = model.DiscordId;
    public string DiscordName { get; private set; } = model.DiscordName;
        // Methods
}

But I ended up in an unsolved problem. When using my code I will work with User objects, right? But I have some questions surrounding this idea (if the best - correct me please if there is any better way).

1) How do I create an instance of User if I don't have a UserModel object? 2) When adding a new UserModel to the DB, how do I do it if I am using User objects throughtout the project, not UserModel objects?

Probably dumb questions but basically, how I keep alternating between their uses? There is probably a better way to do it. If so, please I want to do this the best way possible. I am new to EF Core and SQL Server in general but willing to learn anything to make my project the best version possible.

5 replies

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