Mixing
Can't convert a list of objects with a child list if the child list is empty using linq?
I have this bit of code to convert one list of objects to another list of objects. The code works fine but not if the Messages property is empty. I thought using Any with the ?: operator would fix it but it hasn't, instead I get a Null Reference Exception.
var TemporaryMessageGroupList = MyList.Select(x => new MessageGroupModel()
{
Id = x.Id,
Name = x.Name,
DisplayPicture = x.DisplayPicture,
LastMessage = x.LastMessage,
Archived = x.Archived,
Messages = (x.Messages.Any() ? x.Messages.Select(y => new MessageModel()
{
Id = y.Id,
CreatorId = y.CreatorId,
Content = y.Content,
TimeSent = y.TimeSent,
GroupId = y.GroupId,
HasAttachment = y.HasAttachment,
AttachmentImage = y.AttachmentImage,
IsRead = y.IsRead
}).ToList() : new List<MessageModel>()),
Members = x.Members.Select(c => new UserModel()
{
Id = c.Id,
FullName = c.FullName,
DisplayPicture = c.DisplayPicture
}).ToList()
}).ToList();
I just want to be able to convert one list of objects to another like above, if anyone knows another way to do it to overcome the issue, let me know, thanks!
c# list linq
asked Jan 2 at 19:04
LewisLewis
1515
add a comment |
I have this bit of code to convert one list of objects to another list of objects. The code works fine but not if the Messages property is empty. I thought using Any with the ?: operator would fix it but it hasn't, instead I get a Null Reference Exception.
var TemporaryMessageGroupList = MyList.Select(x => new MessageGroupModel()
{
Id = x.Id,
Name = x.Name,
DisplayPicture = x.DisplayPicture,
LastMessage = x.LastMessage,
Archived = x.Archived,
Messages = (x.Messages.Any() ? x.Messages.Select(y => new MessageModel()
{
Id = y.Id,
CreatorId = y.CreatorId,
Content = y.Content,
TimeSent = y.TimeSent,
GroupId = y.GroupId,
HasAttachment = y.HasAttachment,
AttachmentImage = y.AttachmentImage,
IsRead = y.IsRead
}).ToList() : new List<MessageModel>()),
Members = x.Members.Select(c => new UserModel()
{
Id = c.Id,
FullName = c.FullName,
DisplayPicture = c.DisplayPicture
}).ToList()
}).ToList();
I just want to be able to convert one list of objects to another like above, if anyone knows another way to do it to overcome the issue, let me know, thanks!
c# list linq
asked Jan 2 at 19:04
LewisLewis
1515
x.Messages != null
– Hogan
Jan 2 at 19:07
add a comment |
I have this bit of code to convert one list of objects to another list of objects. The code works fine but not if the Messages property is empty. I thought using Any with the ?: operator would fix it but it hasn't, instead I get a Null Reference Exception.
var TemporaryMessageGroupList = MyList.Select(x => new MessageGroupModel()
{
Id = x.Id,
Name = x.Name,
DisplayPicture = x.DisplayPicture,
LastMessage = x.LastMessage,
Archived = x.Archived,
Messages = (x.Messages.Any() ? x.Messages.Select(y => new MessageModel()
{
Id = y.Id,
CreatorId = y.CreatorId,
Content = y.Content,
TimeSent = y.TimeSent,
GroupId = y.GroupId,
HasAttachment = y.HasAttachment,
AttachmentImage = y.AttachmentImage,
IsRead = y.IsRead
}).ToList() : new List<MessageModel>()),
Members = x.Members.Select(c => new UserModel()
{
Id = c.Id,
FullName = c.FullName,
DisplayPicture = c.DisplayPicture
}).ToList()
}).ToList();
I just want to be able to convert one list of objects to another like above, if anyone knows another way to do it to overcome the issue, let me know, thanks!
c# list linq
asked Jan 2 at 19:04
LewisLewis
1515
I have this bit of code to convert one list of objects to another list of objects. The code works fine but not if the Messages property is empty. I thought using Any with the ?: operator would fix it but it hasn't, instead I get a Null Reference Exception.
var TemporaryMessageGroupList = MyList.Select(x => new MessageGroupModel()
{
Id = x.Id,
Name = x.Name,
DisplayPicture = x.DisplayPicture,
LastMessage = x.LastMessage,
Archived = x.Archived,
Messages = (x.Messages.Any() ? x.Messages.Select(y => new MessageModel()
{
Id = y.Id,
CreatorId = y.CreatorId,
Content = y.Content,
TimeSent = y.TimeSent,
GroupId = y.GroupId,
HasAttachment = y.HasAttachment,
AttachmentImage = y.AttachmentImage,
IsRead = y.IsRead
}).ToList() : new List<MessageModel>()),
Members = x.Members.Select(c => new UserModel()
{
Id = c.Id,
FullName = c.FullName,
DisplayPicture = c.DisplayPicture
}).ToList()
}).ToList();
I just want to be able to convert one list of objects to another like above, if anyone knows another way to do it to overcome the issue, let me know, thanks!
c# list linq
c# list linq
asked Jan 2 at 19:04
LewisLewis
1515
asked Jan 2 at 19:04
LewisLewis
1515
asked Jan 2 at 19:04
LewisLewis
1515
asked Jan 2 at 19:04
LewisLewis
1515
asked Jan 2 at 19:04
LewisLewis
1515
1515
x.Messages != null
– Hogan
Jan 2 at 19:07
add a comment |
x.Messages != null
– Hogan
Jan 2 at 19:07
x.Messages != null– Hogan
Jan 2 at 19:07
x.Messages != null– Hogan
Jan 2 at 19:07
add a comment |
2 Answers
2
active
oldest
votes
Calling Any upon Messages will yield the said exception if Messages is null, instead do:
Messages = x.Messages?.Select(y => new MessageModel()
{
Id = y.Id,
CreatorId = y.CreatorId,
Content = y.Content,
TimeSent = y.TimeSent,
GroupId = y.GroupId,
HasAttachment = y.HasAttachment,
AttachmentImage = y.AttachmentImage,
IsRead = y.IsRead
}).ToList() ?? new List<MessageModel>(),
- This uses the "null-propagation" operator
?.to prevent callingSelectonMessagesif it's null. - We then use the "null coalescing" operator
??to generate a new empty list in the case ofMessagesbeing null.
answered Jan 2 at 19:07
AomineAomine
42.6k74677
add a comment |
you could try something like this, Make sure that x.Messages is not NULL and prefered to be an empty collection if empty, also make sure the properties for Messages are not null for the original object or they are nullable on the receiving object:
Messages = (x.Messages?.Where(msg => msg != null).Select(y => new
MessageModel() {}).ToList()
answered Jan 2 at 19:15
DrormatDrormat
6415
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
Calling Any upon Messages will yield the said exception if Messages is null, instead do:
Messages = x.Messages?.Select(y => new MessageModel()
{
Id = y.Id,
CreatorId = y.CreatorId,
Content = y.Content,
TimeSent = y.TimeSent,
GroupId = y.GroupId,
HasAttachment = y.HasAttachment,
AttachmentImage = y.AttachmentImage,
IsRead = y.IsRead
}).ToList() ?? new List<MessageModel>(),
- This uses the "null-propagation" operator
?.to prevent callingSelectonMessagesif it's null. - We then use the "null coalescing" operator
??to generate a new empty list in the case ofMessagesbeing null.
answered Jan 2 at 19:07
AomineAomine
42.6k74677
add a comment |
Calling Any upon Messages will yield the said exception if Messages is null, instead do:
Messages = x.Messages?.Select(y => new MessageModel()
{
Id = y.Id,
CreatorId = y.CreatorId,
Content = y.Content,
TimeSent = y.TimeSent,
GroupId = y.GroupId,
HasAttachment = y.HasAttachment,
AttachmentImage = y.AttachmentImage,
IsRead = y.IsRead
}).ToList() ?? new List<MessageModel>(),
- This uses the "null-propagation" operator
?.to prevent callingSelectonMessagesif it's null. - We then use the "null coalescing" operator
??to generate a new empty list in the case ofMessagesbeing null.
answered Jan 2 at 19:07
AomineAomine
42.6k74677
add a comment |
Calling Any upon Messages will yield the said exception if Messages is null, instead do:
Messages = x.Messages?.Select(y => new MessageModel()
{
Id = y.Id,
CreatorId = y.CreatorId,
Content = y.Content,
TimeSent = y.TimeSent,
GroupId = y.GroupId,
HasAttachment = y.HasAttachment,
AttachmentImage = y.AttachmentImage,
IsRead = y.IsRead
}).ToList() ?? new List<MessageModel>(),
- This uses the "null-propagation" operator
?.to prevent callingSelectonMessagesif it's null. - We then use the "null coalescing" operator
??to generate a new empty list in the case ofMessagesbeing null.
answered Jan 2 at 19:07
AomineAomine
42.6k74677
Calling Any upon Messages will yield the said exception if Messages is null, instead do:
Messages = x.Messages?.Select(y => new MessageModel()
{
Id = y.Id,
CreatorId = y.CreatorId,
Content = y.Content,
TimeSent = y.TimeSent,
GroupId = y.GroupId,
HasAttachment = y.HasAttachment,
AttachmentImage = y.AttachmentImage,
IsRead = y.IsRead
}).ToList() ?? new List<MessageModel>(),
- This uses the "null-propagation" operator
?.to prevent callingSelectonMessagesif it's null. - We then use the "null coalescing" operator
??to generate a new empty list in the case ofMessagesbeing null.
answered Jan 2 at 19:07
AomineAomine
42.6k74677
edited Jan 2 at 19:16
answered Jan 2 at 19:07
AomineAomine
42.6k74677
answered Jan 2 at 19:07
AomineAomine
42.6k74677
answered Jan 2 at 19:07
AomineAomine
42.6k74677
42.6k74677
add a comment |
add a comment |
you could try something like this, Make sure that x.Messages is not NULL and prefered to be an empty collection if empty, also make sure the properties for Messages are not null for the original object or they are nullable on the receiving object:
Messages = (x.Messages?.Where(msg => msg != null).Select(y => new
MessageModel() {}).ToList()
answered Jan 2 at 19:15
DrormatDrormat
6415
add a comment |
you could try something like this, Make sure that x.Messages is not NULL and prefered to be an empty collection if empty, also make sure the properties for Messages are not null for the original object or they are nullable on the receiving object:
Messages = (x.Messages?.Where(msg => msg != null).Select(y => new
MessageModel() {}).ToList()
answered Jan 2 at 19:15
DrormatDrormat
6415
add a comment |
you could try something like this, Make sure that x.Messages is not NULL and prefered to be an empty collection if empty, also make sure the properties for Messages are not null for the original object or they are nullable on the receiving object:
Messages = (x.Messages?.Where(msg => msg != null).Select(y => new
MessageModel() {}).ToList()
answered Jan 2 at 19:15
DrormatDrormat
6415
you could try something like this, Make sure that x.Messages is not NULL and prefered to be an empty collection if empty, also make sure the properties for Messages are not null for the original object or they are nullable on the receiving object:
Messages = (x.Messages?.Where(msg => msg != null).Select(y => new
MessageModel() {}).ToList()
answered Jan 2 at 19:15
DrormatDrormat
6415
answered Jan 2 at 19:15
DrormatDrormat
6415
answered Jan 2 at 19:15
DrormatDrormat
6415
answered Jan 2 at 19:15
DrormatDrormat
6415
6415
add a comment |
add a comment |
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x.Messages != null– Hogan
Jan 2 at 19:07