使用EventStore HTTP API获取持久化订阅事件返回XML而非JSON求助

调用EventStore HTTP API获取持久化订阅事件时，请求可正常执行，但返回结果为XML格式，而非预期的JSON格式。

请求信息 #

> GET /subscriptions/integration-2023-05-31/Test1_Subscription HTTP/2
> Host: [removed].germanywestcentral.cloudapp.azure.com:2113
> user-agent: insomnia/2023.2.2
> content-type: application/vnd.eventstore.competingatom+json
> authorization: Basic [removed]
> accept: */*

响应信息 #

HTTP/2 200 
< content-type: application/vnd.eventstore.competingatom+xml; charset=utf-8
< date: Wed, 31 May 2023 13:14:01 GMT
< server: Kestrel
< access-control-allow-headers: Content-Type, X-Requested-With, X-Forwarded-Host, X-Forwarded-Prefix, X-PINGOTHER, Authorization, ES-LongPoll, ES-ExpectedVersion, ES-EventId, ES-EventType, ES-RequireMaster, ES-RequireLeader, ES-HardDelete, ES-ResolveLinkTos
< access-control-allow-methods: PUT, POST, DELETE, GET, GET, OPTIONS
< access-control-allow-origin: *
< access-control-expose-headers: Location, ES-Position, ES-CurrentVersion
< content-length: 2033

问题原因 #

你误用了Content-Type头来指定期望的响应格式，但GET请求的Content-Type头不影响响应格式——这个头仅用于告知服务器你发送的请求体类型，而GET请求通常没有请求体。

EventStore的Competing Atom API依赖Accept头协商响应格式，当Accept设为*/*时，服务器会默认返回XML格式。

解决方案 #

将请求的Accept头修改为application/vnd.eventstore.competingatom+json，同时可以移除不必要的Content-Type头（GET请求无需该头），修改后的请求头如下：

> GET /subscriptions/integration-2023-05-31/Test1_Subscription HTTP/2
> Host: [removed].germanywestcentral.cloudapp.azure.com:2113
> user-agent: insomnia/2023.2.2
> authorization: Basic [removed]
> accept: application/vnd.eventstore.competingatom+json

修改后，服务器会根据Accept头返回JSON格式响应，响应的Content-Type也会变为application/vnd.eventstore.competingatom+json。

内容的提问来源于stack exchange，提问作者Sebastian Schabbach