Problem

Sometimes you may want to create a process where uploading a document is mandatory. You can create a single Visualforce page with all of the fields for the record plus the field required to upload a document. You could also develop a wizard interface that allows the user to walk through a series of steps in which one would be to upload a document.

Solution

Create a Visualforce page that references a controller (documented below). Note the enctype attribute on the <apex:form> tag. This Visualforce page uses only the fields necessary for uploading a document but can be expanded to include field for other records or documents in the process.

<apex:page controller="FileUploadController">
  <apex:sectionHeader title="Visualforce Example" subtitle="File Upload Example"/>
 
  <apex:form enctype="multipart/form-data">
    <apex:pageMessages />
    <apex:pageBlock title="Upload a File">
 
      <apex:pageBlockButtons >
        <apex:commandButton action="{!upload}" value="Save"/>
      </apex:pageBlockButtons>
 
      <apex:pageBlockSection showHeader="false" columns="2" id="block1">
 
        <apex:pageBlockSectionItem >
          <apex:outputLabel value="File Name" for="fileName"/>
          <apex:inputText value="{!document.name}" id="fileName"/>
        </apex:pageBlockSectionItem>
 
        <apex:pageBlockSectionItem >
          <apex:outputLabel value="File" for="file"/>
          <apex:inputFile value="{!document.body}" filename="{!document.name}" id="file"/>
        </apex:pageBlockSectionItem>
 
        <apex:pageBlockSectionItem >
          <apex:outputLabel value="Description" for="description"/>
          <apex:inputTextarea value="{!document.description}" id="description"/>
        </apex:pageBlockSectionItem>
 
        <apex:pageBlockSectionItem >
          <apex:outputLabel value="Keywords" for="keywords"/>
          <apex:inputText value="{!document.keywords}" id="keywords"/>
        </apex:pageBlockSectionItem>
 
      </apex:pageBlockSection>
 
    </apex:pageBlock>
  </apex:form>
</apex:page>

public with sharing class FileUploadController {
 
  public Document document {
    get {
      if (document == null)
        document = new Document();
      return document;
    }
    set;
  }
 
  public PageReference upload() {
 
    document.AuthorId = UserInfo.getUserId();
    document.FolderId = UserInfo.getUserId(); // put it in running user's folder
 
    try {
      insert document;
    } catch (DMLException e) {
      ApexPages.addMessage(new ApexPages.message(ApexPages.severity.ERROR,'Error uploading file'));
      return null;
    } finally {
      document.body = null; // clears the viewstate
      document = new Document();
    }
 
    ApexPages.addMessage(new ApexPages.message(ApexPages.severity.INFO,'File uploaded successfully'));
    return null;
  }
 
}

Discussion

Visualforce takes care of all the hard work by updating the document from the file that's uploaded. All your controller class needs to do is store it. If you would like to attach the document to a specific record you will need to use the Attachment object instead of the Document object.

Notes

Make sure you take a look at the finally block in the controller code above. The finally block always executes when the try block exits regardless if an error occurs or not. You need to ensure you clear out document’s body (document.body = null) so that the blob is not automatically included in the serialized image of the controller. If you do not clear out the body, you’ll get the following view state error: "Maximum view state size limit (128K) exceeded. Actual viewstate size for this page was…"