Pass a variable from Javascript to Apex Controller

Question

I'm trying to pass a variable from a javascript inside a VF page to a varibale in the Apex Controller.

The VF page code is:

<apex:page controller="uploadDataTosObject" apiVersion="36.0"> 
[Code....]                  
    <apex:form>
        <script>
            function setVal(result)
            {
                document.getElementById("{!$Component.hdnField}").value =result;
            }
        </script>
        <apex:inputHidden id="hdnField" value="{!myblob}" />
        <apex:commandButton value="Post Page" action="{!post}" />
    </apex:form>
    <script>
        setVal();
    </script>                                                                                            
    <script src="https://cdnjs.cloudflare.com/ajax/libs/es5-shim/4.5.7/es5-shim.js">
   </script>
   <script src="https://cdnjs.cloudflare.com/ajax/libs/xlsx/0.8.0/jszip.js">    </script>
   <script src="https://cdnjs.cloudflare.com/ajax/libs/xlsx/0.8.0/xlsx.js"></script>
     [Code...]    
            function to_csv(workbook) {
                var result = [];
                workbook.SheetNames.forEach(function(sheetName) {
                    var csv = X.utils.sheet_to_csv(workbook.Sheets[sheetName]);
                    if(csv.length > 0){
                        result.push("SHEET: " + sheetName);
                        result.push("");
                        result.push(csv);
                    }
                });
                output = setval(result.join("\n"));
                return result.join("\n");
            }                
[Code...]
    </body>
</apex:page>

this is the VF controller:

public with sharing class uploadDataTosObject {       
    public String myblob {get; set;}        
    public void post(){
        system.debug(myblob);
    }
}

I need to assaign "result.join("\n")" to the variable "myblob" inside the controller. Now I'm trying to use an "apex:inputhidden", but the System.debug shows "undefined" in the Logs. How can I assign the variable "result.join()" to "myblol"?

Answer 1

I'm not able to test if this works currently, but here's what I expect you need:

Page

<apex:page controller="MyClass">
    <apex:inputHidden value="{!content}" ...>
</apex:page>

Controller

public MyClass
{
    public Blob myBlob { get; private set; }
    public String content
    {
        get;
        set { myBlob = Blob.valueOf(value); }
    }
}