string.contains(string) match whole word

Question

In my view,

@using(Html.BeginForm("Action", "Controller", FormMethod.Post)){
<div>
    @Html.TextBox("text_1", " ")
    @Html.TextBox("text_2", " ")
    @if(Session["UserRole"].ToString() == "Manager"){
    @Html.TextBox("anotherText_3", " ")
    }
</div>
<button type="submit">Submit</button>
}

In my controller,

public ActionResult Action(FormCollection form){
    if(!form.AllKeys.Contains("anotherText")){
        ModelState.AddModelError("Error", "AnotherText is missing!");
    }
}

I have a form and post to my method, in my method i want to check if a textbox with id that containing "anotherText", but i use .Contains() it always give false which is not found in my formcollection...How can i do so that it check if the textbox of id containing "anotherText" is existed?

Answer 1

It makes sense that the search would fail, since it's not an exact match.

Try using StartsWith instead, to see if any key starts with the value you're looking for.

if (!form.AllKeys.Any(x => x.StartsWith("anotherText")))
{
    // add error
}

Answer 2

Unlike string.Contains which will return true if the string contains the given substring , what you did here is checking if in the AllKeys (which is a Collection ) there is any Key (a single key - the sub-item of the Collection ) which is of the string "anotherText" .

if(!form.AllKeys.Contains("anotherText"))

Consequently, your sub-item in the Collection is the entire string itself, not the substring of the string

Thus your AllKeys must really contain an exact string that matches it:

"anotherText_2", //doesn't match
"anotherText_1", //doesn't match
"anotherText_3", //doesn't match
"anotherText" //matches

Compare with Contains in a string

string str = "anotherText_3";
str.Contains("anotherText"); //true, this contains "anotherText"

Thus, you should rather check if Any of the Keys have "anotherText" :

if (!form.AllKeys.Any(x => x.Contains("anotherText")))
{
    // add error
}