我试图从AAA000-> ZZZ999调用创建ID的方法。该方法本身工作正常,但是我异步调用它,当同时创建2个或更多案例时,这会引起问题。最大值存储在数据库中(不必存储),我正在尝试这样做:
获得最高当前值->使用我的方法将其递增->保存新的最高值->返回新的最高值。
在使用此方法之前,我只是从Case表中获取最大值。
我已经考虑了几种方法来实现此目的,包括从AAA000播种数据库-> ZZZ999并通过postgres ID递增来查找我的“友好”值。但是,这似乎不是最理想的。
关于如何实现这一目标的任何建议,将不胜感激:
代码概述:
。net核心微服务CQRS亚马逊SQS轨道交通自动贴图MediatR
消费者
public async Task Consume(ConsumeContext<EmailClassified> context)
{
var caseCommand = new CreateCaseFromEmailCommand(context.Message.Classification, context.Message.AiProbability, context.Message.Email);
var newCase = await _mediator.Send(caseCommand);
if (newCase != null)
{
// do something signalR
await Task.CompletedTask;
}
else
{
// log error
await Task.CompletedTask;
}
}
COMMAND
public class CreateCaseFromEmailCommand : IRequest<Case>
{
public string Classification { get; set; }
public decimal AiProbability { get; set; }
public CaseEmail Email { get; set; }
public CreateCaseFromEmailCommand(string classification, decimal aiProbability, CaseEmail email)
{
Classification = classification;
AiProbability = aiProbability;
Email = email;
}
}
HANDLER
public class CreateCaseFromEmailCommandHandler : IRequestHandler<CreateCaseFromEmailCommand, Case>
{
private readonly IMyDbContext _context;
public CreateCaseFromEmailCommandHandler(IMyDbContext context)
{
_context = context;
}
public async Task<Case> Handle(CreateCaseFromEmailCommand request, CancellationToken cancellationToken)
{
try
{
NextIdHelper helper = new NextIdHelper(_context);
string caseReference = helper.GetNextFriendlyId();
var investor = _context.Set<Investor>()
.FirstOrDefault(i => i.EmailAddress.ToLower() == request.Email.FromAddress.ToLower());
var classification = _context.Set<Classification>().Include(t => t.Team)
.FirstOrDefault(c => c.Name.ToLower() == request.Classification.ToLower());
var team = classification.Team;
var entity = new Case()
{
FriendlyCaseId = caseReference,
Summary = request.Email.Subject,
Description = request.Email.Message,
Priority = Priority.Medium,
CaseStatus = CaseStatus.Open,
CreatedDate = DateTime.Now,
NextSla = DateTime.Now.AddDays(1),
Investor = investor,
UnknownInvestorEmail = investor == null ? request.Email.FromAddress : null,
Classification = classification,
Team = team,
AiProbability = request.AiProbability,
Emails = new List<CaseEmail> {request.Email}
};
_context.Set<Case>().Add(entity);
await _context.SaveChangesAsync(cancellationToken);
return entity;
}
catch (Exception ex)
{
return null;
}
}
HELPER
public class NextIdHelper
{
private readonly IMyDbContext _context;
public string Value { get; set; }
public NextIdHelper(IMyDbContext context)
{
_context = context;
}
public string GetNextFriendlyId()
{
var nextValue = "";
var highestId = _context.Set<MaxCaseReference>().FirstOrDefault();
if (!string.IsNullOrWhiteSpace(Value))
{
nextValue = CalculateNextId(Value);
}
else
{
nextValue = CalculateNextId(highestId.Reference);
}
highestId.Reference = nextValue;
Value = nextValue;
_context.SaveChanges();
return nextValue;
}
private string CalculateNextId(string currentId)
{
char[] characters = currentId.ToCharArray();
int currNum = int.Parse(currentId.Substring(currentId.Length - 3));
Tuple<char, char, char, int> id = new Tuple<char, char, char, int>(characters[0], characters[1], characters[2], currNum);
var number = id.Item4 + 1;
var c3 = id.Item3;
var c2 = id.Item2;
var c1 = id.Item1;
if (number > 999)
{
number = 0;
c3++;
if (c3 > 'Z')
{
c3 = 'A';
c2++;
if (c2 > 'Z')
{
c2 = 'A';
c1++;
if (c1 > 'Z')
{
throw new IndexOutOfRangeException("Next ID bigger than \"ZZZ999\"");
}
}
}
}
var next = new Tuple<char, char, char, int>(c1, c2, c3, number);
return $"{next.Item1}{next.Item2}{next.Item3}{next.Item4.ToString().PadLeft(3, '0')}";
}
}
而不是选择和递增字符串,而是使用SEQUENCE或IDENTITY列生成ID,如果需要,则将其转换为客户端上的字符串。 EG
static string GetId(int id)
{
var chars = new char[6];
char Zero = '0';
chars[5] = (char) (Zero + id % 10);
id = id / 10;
chars[4] = (char)(Zero + id % 10);
id = id / 10;
chars[3] = (char)(Zero + id % 10);
id = id / 10;
char A = 'A';
chars[2] = (char)(A + id % 26);
id = id / 26;
chars[1] = (char)(A + id % 26);
id = id / 26;
chars[0] = (char)(A + id % 26);
return new string(chars);
}