selectlist not selecting selected but only for a specific list in ASP.net core v3.1

Question

User-842134713 posted

apologies if this has been answered before but the search function was infinitely spinning 

i have written a routine that looks like this

        public List<GenericSelectListVM> ConvertForSelectList(string stringInput, string defaultChoice="")
        {
            var vals = stringInput.Split(",").ToList();
            List<GenericSelectListVM> list = new List<GenericSelectListVM>();

            foreach (var v in vals)
            {
                var select = new GenericSelectListVM()
                {
                    text = v.Trim(),
                    value = v.Trim(),
                    selected = (defaultChoice == v.Trim() ? true : false)
                };
                list.Add(select);
            }
            return list;
        }

where GenericSelectListVM looks like this :

    public class GenericSelectListVM
    {
        public string value { get; set; }
        public string text { get; set; }
        public bool selected { get; set; }
    }

and here is the view

@{
   if (Model.Hair != null)
   {
      <select asp-for="@Model.HairColor" asp-items='@(new SelectList(Model.Hair, "text", "value"))'></select>
   }
}

so stringInput = "brunette,blonde,redhead,black,grey,dyed" with defaultChoice="blonde" 
this all works great

and when i do this view

@{
   if (Model.ShirtSizes != null)
   {
      <select asp-for="@Model.Shirt" asp-items='@(new SelectList(Model.ShirtSizes, "text", "value"))'></select>
   }
}

so stringInput = "S,M,L" with defaultChoice="S" 
this all works great too

but then when i do this

@{
   if (Model.ShoeSizes != null)
   {
      <select asp-for="@Model.Shoe" asp-items='@(new SelectList(Model.ShoeSizes, "text", "value"))'></select>
   }
}

so stringInput = "5,6,7" with defaultChoice="7" 
this does not work -  the selectlist gets built but the 7 does not get chosen

here is what ConvertForSelectList returns

		selected	false	bool
		text	"brunette"	string
		value	"brunette"	string

		selected	true	bool
		text	"blonde"	string
		value	"blonde"	string
etc

		selected	false	bool
		text	"6"	string
		value	"6"	string

 		selected	true bool
		text	"7"	string
		value	"7"	string
etc

here is the actual markup (minus extraneous stuff)

<select data-val="true" id="HairColor" name="HairColor">
<option value="brunette">brunette</option>
<option selected="selected" value="blonde">blonde</option> <------------------ good
<option value="redhead">redhead</option>
<option value="black">black</option>
<option value="grey">grey</option>
<option value="dyed">dyed</option>
</select>

<select id="Shirt" name="Shirt">
<option selected="selected" value="S">S</option>  <------------------ good
<option value="M">M</option>
<option value="L">L</option>
</select>

<select id="Shoe" name="Shoe">
<option value="5">5</option>
<option value="6">6</option> 
<option value="7">7</option>                   <------------------ missing/annoying!!!
</select>

any ideas why the shoe size might be problematic?

you can see - even tho the sizes are numbers they have been  pre-cast to strings

but that is the only diff i can see between the first two lists and the last

Answer 1

User475983607 posted

To be honest, the code is not somehting you would find in a production application.  Generally, a list of user options is generated from a table not a CSV string passed to a method.  Also, the framework already has classes to handle user options.   I recommend the following Blog as it illustrates standard programming patterns for populating a select to model binding the user's selection.

https://www.learnrazorpages.com/razor-pages/forms/select-lists

Answer 2

User-842134713 posted

hello - sorry for the late reply

im only just seeing this response

while i understand your viewpoint -

this particular usage was not as cookie cutter as just dbcontexting and model-binding a selectlist

i wish it were bc then i wouldnt have had to come on this forum and ask a question 

i do have other selectlists that do that but not this weird one

in this end this all worked out on its own