Java 如何获取Restheart系列的Etag

我正在尝试使用Restheart API删除一个集合

---

$http DELETE 127.0.0.1:8080/testDB/testCollection

获取etag只需

获取127.0.0.1:8080/testDB/testCollection？pagesize=0

，您将在etag响应头的属性和之间找到它

http -a a:a 127.0.0.1:8080/db/coll?pagesize=0
HTTP/1.1 200 OK
...
ETag: 58653f6b2d174c09c590262a**

{
    "_embedded": [], 
    "_etag": {
        "$oid": "58653f6b2d174c09c590262a"
    }, 
    "_id": "coll", 
    "_returned": 0,
}

还要注意，如果发生冲突，尝试删除集合将返回Etag响应头

http -a a:a DELETE 127.0.0.1:8080/db/coll
HTTP/1.1 409 Conflict
...
ETag: 58653f6b2d174c09c590262a

{
    "http status code": 409, 
    "http status description": "Conflict", 
    "message": "The collection's ETag must be provided using the 'If-Match' header."
}

最后，您可以在配置文件中设置Etag检查行为。默认情况下，仅在DELETE/db和/coll上检查etag，但可以对任何写入请求启用etag（例如，为了避免所谓的ghost写入问题）

从conf文件：

#### ETag policy

# the following configuration defines the default etag check policy
# the policy applies for dbs, collections (also applies to file buckets) and documents
# valid values are REQUIRED, REQUIRED_FOR_DELETE, OPTIONAL

etag-check-policy:
    db: REQUIRED_FOR_DELETE
    coll: REQUIRED_FOR_DELETE
    doc: OPTIONAL