C#

var currentYearData = (from p in db.Projects
                        join co in db.Companies on p.CompanyId equals co.Id
                        join cty in db.Cities on p.CityId equals cty.Id
                        join j in db.Jobs on p.Id equals j.ProjectId
                        join jsdr in db.JobStartDateRevisions on j.Id equals jsdr.JobId
                        where jsdr.StartDate >= start && jsdr.StartDate <= end
                        select new { p, c=co, cty, j, jsdr })
                        .OrderBy(x => x.c.CompanyName)
                        .ThenBy(x => x.p.ProjectName)
                        .ThenBy(x => x.jsdr.StartDate)
                        .ToList();

// Step 1 State
class MyInfo {
    public InfoData? Info; 
}

// Step 2 State
class MyInfo {
    public InfoData Info;
}

class MyInfo {
    private _infoData?;
    public InfoData {
        get => _infoData ?? throw ...
        set => _infoData = value
    }
}

class MyInfo {
   public InfoData = InfoData.Empty;

   public static InfoData Empty => new InfoData(); 
}

private void M2_SaidaEfetiva_Click(object sender, EventArgs e)
        {
            if (FormEfetivas == null)
            {
                FormEfetivas = new Frm_Saida();
                FormEfetivas.MdiParent = this;
                FormEfetivas.Text = "Saídas Efetivas";
                FormEfetivas.Tag = "1";
                FormEfetivas.Show();
            }
            FormEfetivas.Activate();
        }
        private void M2_SaidaPrevisao_Click(object sender, EventArgs e)
        {
            if (FormPrevisao == null)
            {
                FormPrevisao = new Frm_Saida();
                FormPrevisao.MdiParent = this;
                FormPrevisao.Text = "Previsão de Saídas";
                FormPrevisao.Tag = "0";
                FormPrevisao.Show();
            }

public class FileAttachment
{
    // other FileAttachment class stuff 
	
    protected void AuthorizeFileAccess(FileAttachmentData file)
    {
        // file has a field which tells which entity it relates to
        // here I need to choose which class to use based on the file data
    }
}


// simplified example of related entity
public class ChatMessage
{
	public int SenderUserId;
	public int RecipientUserId;
	
	// here I need a method that checks that chat message sender's or recipient's
	// user id matches the user id of the logged in user
	// if not, throw exception
}