使用Powershell處理Http Reqest

使用Powershell處理Http Request
(How to handle HTTP request in powershell)

前言

在Linux的世界裡我們可以用cURL發請求去取得Web 上的資源, 而在Windows則可以使用Invoke-WebRequest做到相同的事情

語法

Invoke-WebRequest -Uri $AppUrl -Method Get

例如

$request = 'http://andy.lai.org/ws/2/artist/5b11f4ce-a62d-471e-81fc-a69a8278c7da?inc=aliases&fmt=json'
$response = Invoke-WebRequest $request

得到的response會長這樣

StatusCode : 200
StatusDescription : OK
Content : [{"answer":{"action":{"type":"","uri":""},"image":[],"video":[],"title":"","text":"隨便就可以打開了","speak":""},"intent":"itent_on_computer","slots":[]},{"answer":{
"action":{"type":"","uri":""},"image":[],"v...
RawContent : HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Connection: keep-alive
Content-Length: 477
Content-Type: application/json; charset=utf-8
Date: Sat, 06 Jul 2019 02:30:35 GMT
ETag: W/"1dd-2FGrI1X5h...
Forms : {}
Headers : {[Access-Control-Allow-Origin, *], [Connection, keep-alive], [Content-Length, 477], [Content-Type, application/json; charset=utf-8]...}
Images : {}
InputFields : {}
Links : {}
ParsedHtml : mshtml.HTMLDocumentClass
RawContentLength : 477

這是一個HtmlWebResponseObject 的物件

PS C:\Users\andy> $response.GetType()

IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True False HtmlWebResponseObject Microsoft.PowerShell.Commands.WebResponseObject

當我們只想要body的資訊的時, 可以用 ConvertFrom-JSON將response轉換

$request = 'http://andy.org/ws/2/artist/5b11f4ce-a62d-471e-81fc-a69a8278c7da?inc=aliases&fmt=json'

$reponse = Invoke-WebRequest $request |
ConvertFrom-JSON

結果就會變得很單純的Powershell object

PS C:\Users\1410065> $response

answer intent slots
------ ------ -----
@{action=; image=System.Object[]; video=System.Object[]; title=; text=隨便就可以打開了; speak=} itent_on_computer {}
@{action=; image=System.Object[]; video=System.Object[]; title=; text=有開wifi嗎!; speak=} itent_on_wifi {}
@{action=; image=System.Object[]; video=System.Object[]; title=; text=什麼是序號; speak=} intent_chk_sn {}

從回傳JSON中篩選結果

也可以用Select 語法篩選出自己感興趣的Property

$request = 'http://andy.org/ws/2/artist/5b11f4ce-a62d-471e-81fc-a69a8278c7da?inc=aliases&fmt=json'

Invoke-WebRequest $request |
ConvertFrom-JSON |
Select title, text

除此之外若篩選的對象是內層物件裡的屬性(Embedding Object), 可以用 -expand 把它提取出來再做Select

假設Response body 如下

[
   {
      "answer":{
         "action":{
            "type":"appOpen",
            "uri":""
         },
         "image":[],
         "video":[],
         "title":"",
         "text":"隨便就可以打開了",
         "speak":""
      },
      "intent":"itent_on_computer",
      "slots":[]
   }
   //...
]

若想要篩出 action.type 的資訊的話, 需要下Select -expand action 先把action資訊提出來, 再用Select type 去篩資訊, 完整指令如下

$request = 'http://andy.org/ws/2/artist/5b11f4ce-a62d-471e-81fc-a69a8278c7da?inc=aliases&fmt=json'
Invoke-WebRequest $request |
ConvertFrom-JSON |
Select -expand action | Select type

下載檔案

[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
Invoke-WebRequest -Uri "https://raw.githubusercontent.com/andy51002000/cloud-formation-example/master/cloud_formation.json" -OutFile  ./cloud_formation.json

Ref:

https://devblogs.microsoft.com/scripting/playing-with-json-and-powershell/

黑皮考町

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