SSOM Embed Code when inserting list item

Question

Clicking this button in the list's ribbon, I can properly embed HTML so SharePoint doesn't strip anything out.

I have some HTML that I need to insert into a list item field via C# code. How do I simulate the Embed Code ribbon functionality via C#?

So imagine i'm doing something:

listItem["Body"] = "HTML String";

How do I "Embed" "HTML string" before I insert it?

UPDATE

My apologies, I failed to mention that listItem["Body"] is the body field of a discussion board. Users should still be allowed to manually contribute to the discussion outside of my C# entries.

Answer 1

You can use a calculated column to achieve this. Create a calculated column and set return type as number. Then, simply change the calculated column formula from C#.

Update
A similar way to do this would be using JSLink. You can include the below script in a JS file and place it in your VS solution (typically in your _layouts mapped folder). You wouldn't be able to dynamically change the HTML string though.

(function () {
// Using the fields override leaves the rest of the rendering intact but allows control over one or more fields in the view   
var overrideCtx = {};
overrideCtx.Templates = {};
overrideCtx.Templates.Fields = {
'Body':{'View':EmbedHTML}
};
//Register the template override
SPClientTemplates.TemplateManager.RegisterTemplateOverrides(overrideCtx);
})();
function EmbedHTML(){  
var retVal = ctx.CurrentItem.Body; //to retrieve the field
var HTMLAppendedString;
if(ctx.CurrentItem.ID == ID) //id of item to change
{
   HTMLAppendedString = "<b>"+retVal+"</b>";  //Custom HTML goes here. 
}
else
{
   HTMLAppendedString = retVal;
}
return HTMLAppendedString;
}

You can call this using
spfield.JSLink="location_of_JS_file"
spfield.Update();

Hope this helps you.