How to display content of remote text file in Visualforce page

Question

I am trying to display the contents of a remote text file on a Visualforce Page. I have implemented a class called MyApexClass containing a getTextFileContentAsString method that returns the content of a remote text file as a string.

I then try to invoke that method in the Visualforce page and display it with apex:outputText like so "{!MyApexClass.TextFileContentAsString}". However, I get an error saying:

Error: Unknown property MyApexClass.TextFileContentAsString referenced in MyTemplate. 

What is the correct way to invoke the method, and get the returned string to render on the VisualForce page?

Here are the Apex Class and the VisualForce page excerpts:

Apex Class:

public class MyApexClass {

  public String getTextFileContentAsString() {
    String url = 'http://somehost.com/theTextFile.txt';
    Http h = new Http();
    HttpRequest req = new HttpRequest();
    req.setEndpoint(url);
    req.setMethod('GET');
    HttpResponse res = h.send(req);
    return res.getBody();
  }
}

VisualForce Page excerpt:

...
<div>
<apex:outputText value="{0}">
<apex:param value="{!MyApexClass.TextFileContentAsString}" />
</apex:outputText>
</div>
...

Do I need to do anything special to make the MyApexClass "visible" to the VisualForce page?

Answer 1

Your approach is just fine. It's just lacking an exclamation mark, and the argument should be removed, try:

<apex:param value="{!TextFileContentAsString}" />

Then hard-code the URL into the req.setEndpoint in your Apex class. (Visualforce getters cannot have parameters)

Answer 2

This {!}, is the syntax for merge fields in visualforce. I guess you are missing '!'. You can also cast responce body to string, just to be sure.

Answer 3

Remove () after method name

<apex:outputText value="{!TextFileContentAsString}">
</apex:outputText>

Public class yourController{
   //getter method of controller
   public string getTextFileContentAsString{
     return MyApexClass.TextFileContentAsString();
   }   
}