return html from wcf service

问题:

I have a web service from which I need to return a string containing html. This html is the markup for a Select control (for use in jqGrid search filters), e.g.

<select><option id='1'> value 1 </option></select>  

My WCF web service contains a method that returns this value as a string...

public string GetLeadTypeSelect()
{
    return "<select><option id='1'> value 1 </option></select>";
}  

and the contract for this method is :

[OperationContract]
[WebInvoke(Method = "GET",
    BodyStyle = WebMessageBodyStyle.Bare,
    ResponseFormat = WebMessageFormat.Json)]
string GetLeadTypeSelect();  

My problem is that escape characters are inserted into the string so rendering the returned HTML useless - the service returns this :

"<select><option id='1'> value 1 <\/option><\/select>"  

The quotation marks and the escaped '/' in the closing <option> and <select> tags both cause problems.

jqGrid uses the returned HTML to display the dropdown...

filterModel: [
    { label: 'Type', name: 'type', stype: 'select', surl: '../../../Services/Leads/GetLeads.svc/GetLeadTypeSelect' },

So, my question is, how to I return pure HTML back to the client from this web service so that it can be inserted into my HTML page?

Thanks in advance for any help, Colin.

回答1:

I know this is an old post, but for a service that will only be hosted in IIS, here is an easy way to return html:

[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Required)]
public Stream getHtml()
{
    // get the html
    var html = DoSomethingToGetHtml();  //Not a built-in .Net method ;)

    // we want our result interpreted as plain html
    WebOperationContext.Current.OutgoingResponse.ContentType = "text/html; charset=utf-8";

    // create a stream from our html because trying to return a string adds an extra header tag
    //      to the response.  Returning a stream returns the html by itself
    var result = new MemoryStream(Encoding.UTF8.GetBytes(html));

    // return the result
    return result;
}

This code requires the following in the web.config hosting the service:

<system.serviceModel>
    <!-- enable HttpContext.Current by setting aspNetCompatibilityEnabled=true-->
    <serviceHostingEnvironment aspNetCompatibilityEnabled="true"/>

    <behaviors>
        <endpointBehaviors>
            <behavior name="webHttpEnabled">              
                <webHttp/>
            </behavior>
        </endpointBehaviors>
    </behaviors>
    ...
<system.serviceModel>

In the configuration for the service, set behaviorConfiguration="webHttpEnabled".

Returning html in this way limits the reusability of the service a bit, but it's an easy way to solve the problem if you're reasonably sure the service will always be hosted in IIS.

回答2:

I assume you use it through Javascript.

If you do an unescape(response), your problem should be solved.

On the other hand, if you don't use it in Javascript but just in a ASP.NET / PHP / whatever website you are probably better off by just returning an array of values and display values, so that you can reuse the webservice in other code.

Your piece of code now only works in an HTML environment. What if you need to write a .NET / C++ / whatever app tomorrow that utilizes your webservice? Then you'll need to change it. And that is not the point of webservices. Webservices promote reusability of code. And you are fighting against that. (and the code will win!)