Why does web service return data as msg.d

Question

I found that my webmethod is returning data as ``` { "d": [ {"id":"1","itemtxt":"Masters"}, {"id":"2","itemtxt":"Transactions"}, {"id":"3","itemtxt":"Misch. Reports"} ] } ``` If you notice, the array is named as "d". Why is that ? is there any rule for it? For your information I am returning a list of objects (`List`) ``` public class webitem { public webitem(string kid, string kval) { this.id = kid; this.itemtxt = kval; } public string id { get; set; } public string itemtxt { get; set; } } ``` What does this "d" mean ? will it allways be same for whatever data i send from my webmethod? or it is going to change depending on my data type/class type? EDIT Here is the webmethod ``` [WebMethod] public List GetSubModules(string key) { string s = " order by smid"; if (key != null) s = " where moduleid=" + key + s; return Utility.GetDDLVal("Select smid id,smname itemtxt from m_submodules "+s, null, null); } ```

Accepted Answer

It's a bit of a security feature as part of ASP.NET. It will always be there as long as you don't change serializers. David Ward's blog (now defunct) said what it is:

This is the case with all ASMX services JSON serialized through the ASP.NET AJAX Extensions in ASP.NET 3.5. Even if you’re only returning a scalar return value, such as a string, int, or boolean, the result will always be enclosed within the “d”.

And the why:

{"d": 1 }

Is not a valid JavaScript statement, where as this:

[1]

Is.

So the wrapping of the "d" parameter prevents direct execution of the string as script. No Object or Array constructor worries.

Why does web service return data as msg.d

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