File Content Extraction 25.2
Filter SDK C++ Programming Guide

# Using Document Objects

OpenText recommends that you create a Document object for each document that you want to process, as described in Start Using the Filter API. The document object provides access to the data within a document, including its format, metadata, text, and subfiles.

This topic provides some additional guidance about using document objects in your code.

A `Document` must be created and used on the same thread that created the parent session.

A `Document` object maintains a reference to the input object, so cannot be used after the input object has been destroyed.

## Document Objects and Session Configuration

Changing session configuration options can change the data that is returned by methods of a document object, even if you created the document object before changing the configuration.

Changing your session configuration will also invalidate references previously returned by document object methods.

Consider the following example. You have a document with embedded images but no subfiles and you run the following code:

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    auto session = keyview::Session{license, bin_path};
    session.config().extract_images(false);
    InputFile input(path_to_doc);
    Document doc = session.open(input);

    doc.subfiles().size(); // Returns 0

    session.config().extract_images(true);
    doc.subfiles().size(); // Returns 3

## Password Protected Documents

When you have a `Document` object (named `protected_doc` in this example), you might find that it is password protected. For instance, `protected_doc.info().encrypted()` may be `true`, or `protected_doc.filter()` may throw a `keyview::password_protected_error`. If you know the password, you can configure the session to use that password and then use the existing `Document` object to access the document's contents, as in the following code sample.

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    auto session = keyview::Session{license, bin_path};
    session.config().password("");
    InputFile input(path_to_protected_doc);
    Document protected_doc = session.open(input);

    OutputFile output(path_to_output);
    // protected_doc.filter(output); - would throw

    session.config().password(password);
    protected_doc.filter(output); // does not throw

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Version 25.2 | Last updated April 2025

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Product: File Content Extraction 25.2

Topic Title: Using Document Objects