Example code for HTTP request with JSON information

2015-12-07

Question

_{Monday, December 7, 2015 9:30 PM}

Greetings,

I have a HTTP request to POST JSON data to a web service.

How can I send this HTTP request with a visual basic code?

Regards

Michael

POST http://my.domain.com/api/v3/projects/8/work_packages HTTP/1.1
Content-Type: application/json
Accept-Encoding: gzip, deflate
Host: my.domain.com
Content-Length: 324
Expect: 100-continue
Cookie: _open_project_session=xxxxxxxxxxxxxxxxxxxxxxxxxxxx

{
"subject": "title",
"description": {
    "format": "textile",
    "raw": "example text"
},
"_links": {
    "type": {
      "href": "/api/v3/types/2"
    },
    "status": {
      "href": "/api/v3/statuses/1"
    },
    "priority": {
      "href": "/api/v3/priorities/1"
    },
    "assignee": {
      "href": "/api/v3/users/1"
    },
    "responsible": {
      "href": "/api/v3/users/1"
    }
}
}

All replies (6)

_{Thursday, December 10, 2015 7:21 AM ✅Answered}

Hi Michael-Markus,

Remove below code.

request.Expect = "100-continue"

and insert below code before send your request.

ServicePointManager.Expect100Continue = True

Best Regards,
Li Wang

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_{Tuesday, December 8, 2015 9:42 AM}

Hi Michael-Markus,

You could use HttpWebRequest to send http request. Code below is for your reference.

Dim request As HttpWebRequest = WebRequest.Create("http://my.domain.com/api/v3/projects/8/work_packages HTTP/1.1")
request.Method = "POST"
'add headers
request.Headers.Add("Content-Type", "application/json")
'add other headers
'....
'add body
Dim stream As Stream = request.GetRequestStream()
Dim jsonData As String = "your json"
Dim buffer As Byte() = System.Text.Encoding.UTF8.GetBytes(jsonData)
stream.Write(buffer, 0, buffer.Length)
'send request
request.GetResponse()

Best Regards,
Li Wang

_{Tuesday, December 8, 2015 8:42 PM}

Hello Li Wang,

thank you for the information.

I have tried your code, but I get an error by this line:

request.Headers.Add("Content-Type", "application/json")

"The value is not a valid host header string"

What am I doing wrong?

Thank you!

Michael

_{Wednesday, December 9, 2015 8:55 AM}

Hi Michael,

Change your code as follow.

Dim request As HttpWebRequest = WebRequest.Create("http://my.domain.com/api/v3/projects/8/work_packages HTTP/1.1")
request.Method = "POST"
'add headers
request.ContentType = "application/json;charset=utf-8"
request.Accept = "gzip,deflate"
request.Host = "my.domain.com"
request.ContentLength = 324
request.Expect = "100-continue"
request.Headers.Add("Cookie", "_open_project_session=xxxxxxxxxxxxxxxxxxxxxxxxxxxx")
'add other headers
'....
'add body
Dim stream As Stream = request.GetRequestStream()
Dim jsonData As String = "your json"
Dim buffer As Byte() = System.Text.Encoding.UTF8.GetBytes(jsonData)
stream.Write(buffer, 0, buffer.Length)
'send request
request.GetResponse()

Best Regards,
Li Wang

_{Thursday, December 10, 2015 12:08 AM}

Hello Li Wang,

I have run the code, but I get still an error at the line:

request.Headers.Add("Cookie", "_open_project_session=xxxxxxxxxxxxxxxxxxxxxxxxxxxx")

Argument Exception was unhandled by user code - 100-Continue can not set this parameter

Have you a idea, what are wrong?

Regards

Michael

Private Sub WPerzeugen_Click(sender As Object, e As EventArgs) Handles WPerzeugen.Click

Dim request As HttpWebRequest = WebRequest.Create("http://xyz.dyndns.org/api/v3/projects/8/work_packages HTTP/1.1")
request.Method = "POST"

        request.ContentType = "application/json;charset=utf-8"
        request.Accept = "gzip,deflate"
        request.Host = "xyz.dyndns.org"
        request.ContentLength = 324
        request.Expect = "100-continue"
        request.Headers.Add("Cookie", "_open_project_session=xxxxxxxxxxxxxxxxxxxxxxxxxxxx")

'JSON Anhang zusammen stellen
Dim j As String = ""

j = j & "{ "

'Subject
j = """subject"": " & """" & "Hallo" & ""","

j = j & """_links"": { "

'WP Typ
j = j & """type"": { ""href"": ""/api/v3/types/""" & "2" & """ },"

'WP Status
j = j & """status"": { ""href"": ""/api/v3/statuses/""" & "1" & """ },"

'WP Priority
j = j & """priority"": { ""href"": ""/api/v3/priorities/""" & "1" & """ }"

'Abschluss
j = j & " } }"

        Dim stream As Stream = request.GetRequestStream()
        Dim buffer As Byte() = System.Text.Encoding.UTF8.GetBytes(j)
        stream.Write(buffer, 0, buffer.Length)

'POST request absenden
request.GetResponse()

End Sub

_{Thursday, December 10, 2015 6:22 PM}

...

Private Sub WPerzeugen_Click(sender As Object, e As EventArgs) Handles WPerzeugen.Click

Dim request As HttpWebRequest = WebRequest.Create("http://xyz.dyndns.org/api/v3/projects/8/work_packages HTTP/1.1")
request.Method = "POST"
...

I doubt that the protocol info was supposed to be included in the URL.

Setting the content type to application/json should be the only extra option needed; other than that it should be a standard http post.

You might consider using HttpClient instead of WebRequest/Response. There's an example here in C#, but it is short and simple so should be easy to reproduce in VB.

Reed Kimble - "When you do things right, people won't be sure you've done anything at all"

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Example code for HTTP request with JSON information

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