Set string to empty if no version number exists in Razor HTML

Question

I am building a simple structure in cshtml: if no version number exists, set string to empty, otherwise place a link with version info

<label style="float:right;">
    Version: @resp.VersionNumber
    @if (string.IsNullOrEmpty(@resp.VersionNumber))
    {
         @resp.VersionNumber == "";
    }
    else
    {
         <a>Version link code</a>
    }
</label>

Resp is JsonResponce local variable, while VersionNumber is a string Datamember of JsonResponce class.

While it looks extremely easy, it was returning errors that made me scratch my head.

The error is inside the if statement. I tried encasing the line in the () like was suggested by accepted answer in that thread, but it was returning a compilation error, like in that post. Structures in both cases are a bit different than mine, so I cannot exactly apply those.

If I leave the line inside if as is, it was returning compilation errors of invalid expression term == and expected ; , even though I already have it.

I understand that I am probably missing something simple, but can you please point me to how I should change my code in order to remove those errors. And briefly explain why it is doing this, since I want to learn from this question as well.

I am a beginner self-learner in that area, so please go easy on me. Thank you very much!

UPDATE

Based on everyones's proposed suggestions, I rearranged my code, and now it looks like the following

<label style="float:right;">
     Version: 
     @if (string.IsNullOrEmpty(resp.VersionNumber))
     {
         <span></span>;
     }
         else
     {
         @resp.VersionNumber
         <a>Version link code</a>
     }
</label>

`=` is for assigning a value, `==` is for comparing values. – David Aug 17 '16 at 18:26 — David, Aug 17 '16 at 18:26

score 2 · Accepted Answer · answered Aug 17 '16 at 18:31

2

You have several errors. First you have @ in places where it doesn't belong, since you're already in a code block. You use comparison (==) when you most likely want assignment(=). You also first output the value and then want to modify it.

Most likely you are after something like this

<label style="float:right;">
  Version:
  @if (string.IsNullOrEmpty(resp.VersionNumber))
  {
    <span>No version number!</span>
  } else {
    <a>Version link code</a>
  }
</label>

This way you check if it exists, if not you just output a text and if it does you do the link how you want.

answered Aug 17 '16 at 18:31

Sami Kuhmonen

30,146
9
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Your answer was the closest to give me the desired result. I'll edit my post and accept your answer once limit is over. – Vadzim Savenok Aug 17 '16 at 18:38
Also, can you please briefly explain this whole @ misplacement or point me to some good sources to it? – Vadzim Savenok Aug 17 '16 at 18:45
1

@VadzimSavenok @ starts a code block, so you only use it for that. You don't need it in the middle of the code ever. Good starting point http://www.asp.net/web-pages/overview/getting-started/introducing-razor-syntax-c – Sami Kuhmonen Aug 17 '16 at 18:47
Thank you, I will definitely look into it! – Vadzim Savenok Aug 17 '16 at 18:48

score 0 · Answer 2 · answered Aug 17 '16 at 18:28

0

This

 @resp.VersionNumber == "No version number!";

should be

 @resp.VersionNumber = "No version number!";

You use == to compare values, use = to assign values:

Assignment: https://msdn.microsoft.com/en-us/library/sbkb459w.aspx
Equality: https://msdn.microsoft.com/en-us/library/53k8ybth.aspx

answered Aug 17 '16 at 18:28

nimeshjm

1,665
10
13

I just tried it, it was returning same 2 errors, except it was `invalid expression term =` – Vadzim Savenok Aug 17 '16 at 18:29

Nkosi · Answer 3 · 2016-08-17T18:38:50.963

0

This will only show the version related info if a version number exists

<label style="float:right;">
    @if (!string.IsNullOrEmpty(resp.VersionNumber)) {
        Version: @Html.ActionLink(resp.VersionNumber, "actionName", "controllerName")
    }
</label>

edited Aug 17 '16 at 18:38

answered Aug 17 '16 at 18:30

Nkosi

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Set string to empty if no version number exists in Razor HTML

UPDATE

3 Answers3