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  • shapper
    #1

    Property

    Hello,

    I have the following properties in a class:

    public List<ObjAA { 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
    Tags: None
    • Jon Skeet [C# MVP]
      #2
      Re: Property

      On Sep 26, 1:24 pm, shapper <mdmo...@gmail. comwrote:
      I have the following properties in a class:
      >
          public List<ObjAA { 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).ToArra y(); }
      }

      Jon

        Comment

        • shapper
          #3
          Re: Property

          On Sep 26, 1:31 pm, "Jon Skeet [C# MVP]" <sk...@pobox.co mwrote:
          On Sep 26, 1:24 pm, shapper <mdmo...@gmail. comwrote:
          >
          I have the following properties in a class:
          >
              public List<ObjAA { 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).ToArra y(); }
          >
          }
          >
          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).ToArra y());

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

          And yes it should be writable.

          Thanks,
          Miguel


            Comment

            • Jon Skeet [C# MVP]
              #4
              Re: Property

              On Sep 26, 2:01 pm, shapper <mdmo...@gmail. comwrote:
              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).ToArra y());
              >
              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

                Comment

                • shapper
                  #5
                  Re: Property

                  On Sep 26, 2:09 pm, "Jon Skeet [C# MVP]" <sk...@pobox.co mwrote:
                  On Sep 26, 2:01 pm, shapper <mdmo...@gmail. comwrote:
                  >
                  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).ToArra y());
                  >
                  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
                  Yes, problem when typing. It is:
                  string.Join(", ", A.Select(x =x.Name).ToArra y());

                  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.

                    Comment

                    • Jon Skeet [C# MVP]
                      #6
                      Re: Property

                      On Sep 26, 2:13 pm, shapper <mdmo...@gmail. comwrote:
                      Yes, problem when typing. It is:
                        string.Join(", ", A.Select(x =x.Name).ToArra y());
                      >
                      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

                        Comment

                        • shapper
                          #7
                          Re: Property

                          On Sep 26, 2:25 pm, "Jon Skeet [C# MVP]" <sk...@pobox.co mwrote:
                          On Sep 26, 2:13 pm, shapper <mdmo...@gmail. comwrote:
                          >
                          Yes, problem when typing. It is:
                            string.Join(", ", A.Select(x =x.Name).ToArra y());
                          >
                          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
                          I am a little bit confuse about this. I am using the following:

                          public class PostPaper {

                          public Post Post { get; set; }
                          public List<TagTags {
                          get;
                          set {
                          Tags = this.TagsCSV.Sp lit(',').Select (t =new Tag { Name =
                          t.Trim() }).ToList();
                          }
                          }
                          public string TagsCSV {
                          get {
                          return string.Join(", ", this.Tags.Selec t(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.PostsT ags
                          join t in database.Tags on pt.TagID
                          equals t.TagID
                          where pt.PostID == id
                          orderby t.Name
                          select t).ToList()
                          }).SingleOrDefa ult();
                          }

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

                          Thanks,
                          Miguel

                            Comment

                            • Jon Skeet [C# MVP]
                              #8
                              Re: Property

                              shapper <mdmoura@gmail. comwrote:
                              On Sep 26, 2:25 pm, "Jon Skeet [C# MVP]" <sk...@pobox.co mwrote:
                              On Sep 26, 2:13 pm, shapper <mdmo...@gmail. comwrote:
                              Yes, problem when typing. It is:
                                string.Join(", ", A.Select(x =x.Name).ToArra y());
                              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
                              I am a little bit confuse about this. I am using the following:

                              public class PostPaper {

                              public Post Post { get; set; }
                              public List<TagTags {
                              get;
                              set {
                              Tags = this.TagsCSV.Sp lit(',').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.PostsT ags
                              join t in database.Tags on pt.TagID
                              equals t.TagID
                              where pt.PostID == id
                              orderby t.Name
                              select t).ToList()
                              }).SingleOrDefa ult();
                              }

                              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.

                              --
                              Jon Skeet - <skeet@pobox.co m>
                              Web site: http://www.pobox.com/~skeet
                              Blog: http://www.msmvps.com/jon.skeet
                              C# in Depth: http://csharpindepth.com

                                Comment

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