Property

[shapper]

Hello,

I have the following properties in a class:

public List<ObjA> A { get; set; }
public string B { get; set; }

B is always an array created from A.Name property in all A property.

How can I define B as described? I am using Net 3.5 so I can use Linq.

Thanks,
Miguel

 

[Jon Skeet [C# MVP]]

I have the following properties in a class:

    public List<ObjA> A { get; set; }
    public string B { get; set; }

B is always an array created from A.Name property in all A property.

B isn't an array at all, it's a string. Did you mean to declare it as
a string[]?

How can I define B as described? I am using Net 3.5 so I can use Linq.

Should B really be writable? If not, you might want:

public string[] B
{
get { return A.Select(x => x.Name).ToArray(); }
}

Jon

 

[shapper]

I have the following properties in a class:

    public List<ObjA> A { get; set; }
    public string B { get; set; }

B is always an array created from A.Name property in all A property.

B isn't an array at all, it's a string. Did you mean to declare it as
a string[]?

How can I define B as described? I am using Net 3.5 so I can use Linq.

Should B really be writable? If not, you might want:

public string[] B
{
    get { return A.Select(x => x.Name).ToArray(); }

}

Jon

I did a mistake: I want it to be in a CSV format so I changed your
code to:
string.Join(", ", return A.Select(x => x.Name).ToArray());

Is this ok? Maybe I could do this directly from the list?

And yes it should be writable.

Thanks,
Miguel

 

[Jon Skeet [C# MVP]]

I did a mistake: I want it to be in a CSV format so I changed your
code to:
string.Join(", ", return A.Select(x => x.Name).ToArray());

Is this ok? Maybe I could do this directly from the list?

Your "return" is in the wrong place, but otherwise it should work.
It's not terribly efficient (because ToArray will copy everything),
but it'll work.

And yes it should be writable.

What will you make it do if someone writes to it then? Split the
value, check the length is right and assign the names within A?
Doesn't sound terribly nice.

Jon

 

[shapper]

Your "return" is in the wrong place, but otherwise it should work.
It's not terribly efficient (because ToArray will copy everything),
but it'll work.


What will you make it do if someone writes to it then? Split the
value, check the length is right and assign the names within A?
Doesn't sound terribly nice.

Jon

Yes, problem when typing. It is:
string.Join(", ", A.Select(x => x.Name).ToArray());

So how should I do it to make it more efficient?

The writable part is still under thinking ... this class is ViewData
to communicate between a View and a Controller.

 

[Jon Skeet [C# MVP]]

Yes, problem when typing. It is:
  string.Join(", ", A.Select(x => x.Name).ToArray());

So how should I do it to make it more efficient?

Unfortunately I suspect you'd need to write your own implementation of
String.Join. (It takes an array, right?)

The writable part is still under thinking ... this class is ViewData
to communicate between a View and a Controller.

But does that part need to be modifiable?

Jon

 

[shapper]

Unfortunately I suspect you'd need to write your own implementation of
String.Join. (It takes an array, right?)


But does that part need to be modifiable?

Jon

I am a little bit confuse about this. I am using the following:

public class PostPaper {

public Post Post { get; set; }
public List<Tag> Tags {
get;
set {
Tags = this.TagsCSV.Split(',').Select(t => new Tag { Name =
t.Trim() }).ToList();
}
}
public string TagsCSV {
get {
return string.Join(", ", this.Tags.Select(t =>
t.Name).ToArray()); ;
}
set;
}

Sometimes I define Tags by converting from TagsCSV ... but sometime I
can also do this using Linq as follows:

PostPaper paper = (from p in database.Posts
where p.PostID == id
select new PostPaper {
Post =
p,
Tags = (from pt in database.PostsTags
join t in database.Tags on pt.TagID
equals t.TagID
where pt.PostID == id
orderby t.Name
select t).ToList()
}).SingleOrDefault();
}

Can I integrate this on my properties? Or maybe on my class?

Thanks,
Miguel

 

[Jon Skeet [C# MVP]]

I am a little bit confuse about this. I am using the following:

public class PostPaper {

public Post Post { get; set; }
public List<Tag> Tags {
get;
set {
Tags = this.TagsCSV.Split(',').Select(t => new Tag { Name =
t.Trim() }).ToList();
}
}

You've got a problem there to start with - you're assigning to Tags
from within Tags, and you haven't provided a getter.

Sometimes I define Tags by converting from TagsCSV ... but sometime I
can also do this using Linq as follows:

PostPaper paper = (from p in database.Posts
where p.PostID == id
select new PostPaper {
Post =
p,
Tags = (from pt in database.PostsTags
join t in database.Tags on pt.TagID
equals t.TagID
where pt.PostID == id
orderby t.Name
select t).ToList()
}).SingleOrDefault();
}

Can I integrate this on my properties? Or maybe on my class?

I don't think we know nearly enough about what you're trying to do at
this point, I'm afraid. I doubt that you really want to do a database
lookup each time someone accesses a property though.