# Extending OpenAPI { #extending-openapi }

There are some cases where you might need to modify the generated OpenAPI schema.

In this section you will see how.

## The normal process { #the-normal-process }

The normal (default) process, is as follows.

A `FastAPI` application (instance) has an `.openapi()` method that is expected to return the OpenAPI schema.

 * It writes data to a temporary file once the data size exceeds a specified threshold.
 *
 * <p>This class ensures that the temporary file is deleted if it is not needed.
 * It uses a logger to log warnings if there are issues deleting the temporary file.</p>
 *
 * <p>Fields:</p>
 * <ul>
 *   <li>{@code logger} - Logger instance for logging warnings.</li>
 *   <li>{@code PREFIX} - Prefix for the temporary file name.</li>

* Then it returns the **response**.

/// note | Technical Details

If you have dependencies with `yield`, the exit code will run *after* the middleware.

If there were any background tasks (covered in the [Background Tasks](background-tasks.md){.internal-link target=_blank} section, you will see it later), they will run *after* all the middleware.

///

{* ../../docs_src/security/tutorial002_an_py310.py hl[30:32] *}

## Recap { #recap }

You can now get the current user directly in your *path operation function*.

We are already halfway there.

We just need to add a *path operation* for the user/client to actually send the `username` and `password`.

import org.jspecify.annotations.Nullable;

/**
 * To be implemented by test generators of things that can contain elements. Such things include
 * both {@link Collection} and {@link Map}; since there isn't an established collective noun that
 * encompasses both of these, 'container' is used.
 *
 * @author George van den Driessche
 */
@GwtCompatible
@NullMarked

     */
    @Override
    public void releaseBuffer(final byte[] buf) {
        if (buf == null) {
            return;
        }
        // better safe than sorry: prevent leaks if there is some out of bound access
        Arrays.fill(buf, (byte) 0);
        synchronized (this.cache) {
            if (this.freeBuffers < this.cache.length) {
                for (int i = 0; i < this.cache.length; i++) {

     *
     * @return the expiration time of this entry
     */
    long getExpiration();

    /**
     * Get the next referral in the chain
     *
     * @return pointer to next referral, points to self if there is no further referral
     */
    DfsReferralData next();

    /**
     * Get the complete UNC path link for this referral
     *
     * @return the link
     */
    String getLink();

        // Problems here with iSeries returning ASCII even though useUnicode = true
        // Fortunately we don't really need nativeFileSystem for anything.
        // However, we'll try to read it safely for compatibility
        if (this.byteCount > bufferIndex - start) {
            try {
                // Attempt to read nativeFileSystem, but don't fail if there are issues

import org.jspecify.annotations.Nullable;

/**
 * To be implemented by test generators of things that can contain elements. Such things include
 * both {@link Collection} and {@link Map}; since there isn't an established collective noun that
 * encompasses both of these, 'container' is used.
 *
 * @author George van den Driessche
 */
@GwtCompatible
@NullMarked

    String[] WINERR_MESSAGES = { "The operation completed successfully.", "Access is denied.",
            "No more connections can be made to this remote computer at this time because there are already as many connections as the computer can accept.",
            "The pipe state is invalid.", "All pipe instances are busy.", "The pipe is being closed.",