[英]NHibernate QueryOver projections - projecting collections to DTO
我正在嘗試將實體的集合投影到DTO中。 使用簡單的屬性很容易,但是集合有問題:
public class Blog
{
public string Name {get;set;}
public IList<Comments> Comments {get;set;}
//... more properties
}
public class Comments
{
public Blog Blog {get;set;}
//... more properties
}
public class MyDTO
{
public string BlogName {get;set;}
public IList<Comments> {get;set;}
}
查詢有點像:
var dto = _session.QueryOver<Blog>(() => blogAlias)
.JoinAlias(x => x.Comments, () => commentsAlias, JoinType.LeftOuterJoin)
.Select(
Projections.Property(() => blogAlias.Reference).WithAlias(() => myDTO.Reference),
// what project here to project blogAlias.Comments into myDTO.Comments))
.TransformUsing(Transformers.AliasToBean<MyDTO>()
.SingleOrDefault<MyDTO>();
編輯更新
即使沒有變換,我也似乎無法運行簡單的投影並得到:“索引超出了數組的范圍”:
var dto = _session.QueryOver<Blog>(() => blogAlias)
.JoinAlias(x => x.Comments, () => commentsAlias, JoinType.LeftOuterJoin)
.Select(
Projections.Property(() => blogAlias.Reference).WithAlias(() => myDTO.Reference),
Projections.Property(() => blogAlias.Comments).WithAlias(() => myDTO.Comments)
.List<object>();
我猜這是你應該做的..
將您的DTO更新為:
public class MyDTO
{
public string BlogName {get;set;}
public IList<Comments> Comments {get;set;}
}
您修改后的查詢:
var dto = _session.QueryOver<Blog>(() => blogAlias)
.JoinAlias(x => x.Comments, () => commentsAlias, JoinType.LeftOuterJoin)
.Select(Projections.Property(() => blogAlias.Reference).WithAlias(() => myDTO.Reference),
Projections.Property(() => blogAlias.Comments).WithAlias(() => myDTO.Comments),
.TransformUsing(Transformers.AliasToBean<MyDTO>()
.SingleOrDefault<MyDTO>()
如果那不起作用那么
_session.QueryOver<Blog>(() => blogAlias)
.JoinAlias(x => x.Comments, () => commentsAlias, JoinType.LeftOuterJoin)
.Select(Projections.Property(() => blogAlias.Reference),
Projections.Property(() => blogAlias.Comments))
.SingleOrDefault<object[]>()
.Select(x=>new MyDTO {BlogName=(string)x[0],Comments=x[1].Select(y=>y.ToString()).ToList())};
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