Question

我有以下DTO：

public class QuestionGroupDTO : IBaseDTO
{
    public string Description { get; set; }
    public string Header { get; set; }
    public Guid Id { get; set; }
    public int Order { get; set; }
    public IEnumerable<Services.Forms.Models.RelationForm_QuestionGroupDTO> RelationForms_QuestionGroups { get; set; }
    public IEnumerable<RelationQuestionGroup_QuestionDTO> RelationQuestionGroups_Questions { get; set; }
}

我在转换时遇到RelationQuestionGroups_Questions问题。

以下是我RelationQuestionGroup_QuestionDTO的样子

public class RelationQuestionGroup_QuestionDTO
{
    public int Order { get; set; }
    [Required]
    public Guid QuestionGroupId { get; set; }
    [Required]
    public Guid QuestionId { get; set; }

    public virtual QuestionGroupDTO QuestionGroup { get; set; }
    public virtual QuestionDTO Question { get; set; }
}

以下是我的转换方式：

public static QuestionGroupDTO ToDTO(this QuestionGroup src)
{
    var dto = new QuestionGroupDTO
    {
        Id = src.Id,
        Header = src.Header,
        Description = src.Description,
        RelationQuestionGroups_Questions = src.RelationQuestionGroups_Questions.ToList()
    };
    return dto;
}

正如你所看到的，我试图分配它并列出它，但我在这里得到了一个转换错误。我不知道该怎么做。

我收到以下错误：

无法将类型通用列表转换为System.Collections.Generic.IEnumerble

Answer 1

您的映射开始很好，但在RelationQuestionGroups_Questions = src.RelationQuestionGroups_Questions.ToList()，您尝试将List<Entity>分配给List<Dto>。你不能这样做。

您还需要映射任何非基本属性。你可以这样做：

public static QuestionGroupDTO ToDTO(this QuestionGroup src)
{
    var dto = new QuestionGroupDTO
    {
        // ...
        RelationQuestionGroups_Questions = src.RelationQuestionGroups_Questions
                                              .Select(ToDTO)
                                              .ToList()
    };
    return dto;
}

然后添加一个方法，将RelationQuestionGroups_Question映射到RelationQuestionGroups_QuestionDTO：

public RelationQuestionGroups_QuestionDTO ToDTO(RelationQuestionGroups_Question entity)
{
    return new RelationQuestionGroups_QuestionDTO
    {
        Order = entity.Order,
        // ...
    };
}

然后你会去看看AutoMapper来实现自动化。

Answer 2

您忘了将 RelationQuestionGroups_Questions 映射到 RelationQuestionGroup_QuestionDTO 。

public static QuestionGroupDTO ToDTO(this QuestionGroup src)
{
    var dto = new QuestionGroupDTO
    {
        Id = src.Id,
        Header = src.Header,
        Description = src.Description,
        RelationQuestionGroups_Questions = src.RelationQuestionGroups_Questions.Select(rq => new RelationQuestionGroup_QuestionDTO
            {
                Order = rq.Order,
                QuestionGroupId = rq.QuestionGroupId,
                QuestionId = rq.QuestionId
            }).ToList()
        };
    return dto;
}

转换为DTO列表属性

2 个答案: