Question

我目前在我的c＃MVC项目中使用AutoMapper，遇到了从整数转换为字符串的问题。

我有两个班级：

public class Job
{
    public string Prefix { get; set; }
    public int JobNumber { get; set; }
    public int Year { get; set }
    public int JobPriority { get; set; }

    public virtual EntityPriority EntityPriority { get; set; }
}

public class JobViewModel
{
    public string JobNumberFull { get; set; }
{

使用Automapper我想连接Job类中的所有三个属性以形成一个字符串，然后将其映射到JobViewModel类中的JobNumberFull。：

前缀jobnumber可以年

首先，我保持简单，不将字段连接成字符串，我刚刚尝试使用JobNumber（int）并将其映射到JobNumberFull（字符串），如下所示：

Mapper.CreateMap<int, string>().ConvertUsing(Convert.ToString);
Mapper.CreateMap<Job, JobViewModel>()
    .ForMember(d => d.JobPriorityId, opt => opt.MapFrom(s => s.EntityPriority.EntityPriorityID))
    .ForMember(d => d.JobPriorityLevel, opt => opt.MapFrom(s => s.EntityPriority.PriorityLevel))
    .ForMember(d => d.JobNumberFull, opt => opt.MapFrom(s => s.JobNumberYear));
Mapper.AssertConfigurationIsValid();

var jobsList = db.Jobs.Where(j => j.OperationID == operationId).Project().To<JobViewModel>().ToList();

当我运行时，我收到以下错误

Type 'System.String' does not have a default constructor

我知道这与

有关

Convert.ToString

但我不知道该怎么办！当从字符串转到int时，我可以做Convert.ToInt32，它就像一个款待。我是否需要创建自定义类型转换器？

我如何获得字符串prefix-jobnumber-year？

非常感谢。

更新

感谢Jeremy和AutoMapper网站的帮助，我设法让这个工作在我的解决方案中，如果您认为有更优雅的解决方案，请随时发表评论：

public class Job 
{
    public string Prefix { get; set; }
    public int JobNumber { get; set; }
    public int Year { get; set; }
    public int JobPriority { get; set; }

    public virtual EntityPriority EntityPriority { get; set; }
}

public class JobViewModel 
{
    public int JobNumber { get; set; }
    public int Year { get; set; }
    public string JobNumberFull { get; set; }
}

public enum EntityPriority 
{
  Normal = 0,
  High
}

public interface IValueResolver
{
   ResolutionResult Resolve(ResolutionResult source);
}

public class JobNumberConverter : ValueResolver<Job, string>
{
    protected override string ResolveCore(Job source)
    {
        return string.Format("{0}-{1}-{2}", source.Prefix, source.JobNumber, source.Year);
    }
}

public ActionResult Index()
{
    Mapper.CreateMap<Job, JobViewModel>()
        .ForMember(jvm => jvm.JobNumberFull, opt => opt.ResolveUsing<JobNumberConverter>());
    Mapper.AssertConfigurationIsValid();

    List<Job> jobs = new List<Job>();

    Job j = new Job()
    {
        JobNumber = 1,
        Prefix = "prefix",
        Year = 2013,
        EntityPriority = EntityPriority.High,
        JobPriority = 2
    };

    Job j2 = new Job()
    {
        JobNumber = 2,
        Prefix = "prefix",
        Year = 2013,
        EntityPriority = EntityPriority.High,
        JobPriority = 2
    };

    Job j3 = new Job()
    {
        JobNumber = 3,
        Prefix = "prefix",
        Year = 2013,
        EntityPriority = EntityPriority.High,
        JobPriority = 2
    };

    jobs.Add(j);
    jobs.Add(j2);
    jobs.Add(j3);

    var jobViewModels = jobs.Select(job => Mapper.Map<JobViewModel>(job));

    return View();

}

Answer 1

我认为您可以使用ResolveUsing方法来解决它。

Mapper.CreateMap<Job, JobViewModel>()
    .ForMember(d => d.JobNumberFull,
    exp =>
    exp.ResolveUsing(j => string.Format("{0}-{1}-{2}", j.Prefix, j.JobNumber, j.Year)));

Answer 2

您需要为从Job到JobViewModel的转换指定自定义转换函数。

Mapper.CreateMap<Job, JobViewModel>().ConvertUsing(
  job => new JobViewModel {
    JobNumberFull = string.Format("{0}-{1}-{2}",
                      job.Prefix, job.JobNumber, Job.Year)
  });

要将Job转换为JobViewModel，请使用Map函数。

var jobViewModel = Mapper.Map<JobViewModel>(job);

要将作业列表转换为JobViewModel，请使用Select扩展名方法。

var jobViewModels = jobs.Select(job => Mapper.Map<JobViewModel>(job));

Automapper：将int转换为字符串

2 个答案: