* 「路徑」可以包含一個 [OpenAPI 3 表達式](https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.1.0.md#key-expression)（見下文），可使用參數與原始送到「你的 API」的請求中的部分欄位。

### 回呼路徑表達式 { #the-callback-path-expression }

回呼的「路徑」可以包含一個 [OpenAPI 3 表達式](https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.1.0.md#key-expression)，能引用原本送到「你的 API」的請求中的部分內容。

在這個例子中，它是一個 `str`：

```Python

    @Required
    @Size(max = 1000)
    public String id;

    /**
     * The version number of the user for optimistic locking.
     * This field is required to prevent concurrent modification conflicts
     * by ensuring the user hasn't been modified by another process.
     */
    @Required
    @ValidateTypeFailure
    public Integer versionNo;

| Maximum length for '/' separated object name segment                            | 255                                                                             |
| Maximum number of versions per object                                           | 10000 (can be configured to higher values but we do not recommend beyond 10000) |

    //
    // or we can show it graphically as:
    //
    // p1 ---> p0 --> super model
    //
    // p1 has a depMgmt section that specifies versions 1.0 of jars "a" & "b"
    // jar "a" has a transitive dependency on 2.0 of jar "b", but maven should
    // prefer to use version 1.0.
    //
    // ----------------------------------------------------------------------

    @Test

# returns the hash of a specific reference, like 'default' or a tag.
# And golookup of a hash confirms that it still exists on the server.
# We can use that to revalidate that specific versions still exist and
# have the same meaning they did the last time we checked.
#
# Usage:
#
#	hg --config "extensions.goreposum=$GOROOT/lib/hg/goreposum.py" goreposum REPOURL

import base64, hashlib, sys

versions of the General Public License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns.

Each version is given a distinguishing version number. If the Program
specifies a version number of this License which applies to it and "any
later version", you have the option of following the terms and

        String version = artifact.getBaseVersion();
        String classifier = artifact.getClassifier();
        String extension = artifact.getExtension();
        return getArtifactPath(groupId, artifactId, version, classifier, extension);
    }

    private Path getArtifactPath(
            String groupId, String artifactId, String version, String classifier, String extension) {

    public String updatedBy;

    /** Timestamp when this entry was last updated */
    @ValidateTypeFailure
    public Long updatedTime;

    /** Version number for optimistic locking */
    @Required
    @ValidateTypeFailure
    public Integer versionNo;

    /**
     * Default constructor for EditForm.
     */
    public EditForm() {
        super();
    }

fun Directory.parentOrRoot(): Directory = if (this.file("version.txt").asFile.exists()) {
    this
} else {
    val parent = dir("..")
    when {
        parent.file("version.txt").asFile.exists() -> parent
        this == parent -> error("Cannot find 'version.txt' file in root of repository")
        else -> parent.parentOrRoot()
    }
}

{* ../../docs_src/templates/tutorial001_py310.py hl[4,11,15:18] *}

/// note | Remarque

Avant FastAPI 0.108.0 et Starlette 0.29.0, `name` était le premier paramètre.

De plus, auparavant, dans les versions précédentes, l'objet `request` faisait partie des paires clé-valeur du contexte pour Jinja2.

///

/// tip | Astuce