Post JSON to Python CGI

I have got Apache2 Installed and Python working.

I am having a problem though. I have two pages.

One a Python Page and the other an Html Page with JQuery

Can someone please tell me how I can get my ajax post to work correctly.

<html>

<head>



</head>

<body>

<script>

    $(function()

    {

        alert('Im going to start processing');



        $.ajax({

            url: "saveList.py",

            type: "post",

            data: {'param':{"hello":"world"}},

            dataType: "application/json",

            success : function(response)

            {

                alert(response);

            }

        });

    });

</script>

</body>

</html>

And the Python Code

import sys

import json



def index(req):

    result = {'success':'true','message':'The Command Completed Successfully'};



    data = sys.stdin.read();



    myjson = json.loads(data);



    return str(myjson);

edited May 23 '12 at 13:10

asked May 23 '12 at 10:59

TheMonkeyMan

2,95151833

Presumably, nothing happens? Please tell us the problems you see.

– Martijn Pieters♦
May 23 '12 at 11:03

Are you posting a JSON or a JSON-string which is percentile-encoded?

– UltraInstinct
May 23 '12 at 11:37

I just want it so it shows me what I posted in so I have an idea that it actually works. Insted of it at present returning "null"

– TheMonkeyMan
May 23 '12 at 13:14

@Deano Well, your question first was not very clear. Now you can check the updated version of my answer. It should work.

– VisioN
May 23 '12 at 13:52

Why is there a semicolon after each statement in the python code above? An error, I assume?

– Sudipta Chatterjee
Jan 8 '13 at 23:23

add a comment |

I have got Apache2 Installed and Python working.

I am having a problem though. I have two pages.

One a Python Page and the other an Html Page with JQuery

Can someone please tell me how I can get my ajax post to work correctly.

<html>

<head>



</head>

<body>

<script>

    $(function()

    {

        alert('Im going to start processing');



        $.ajax({

            url: "saveList.py",

            type: "post",

            data: {'param':{"hello":"world"}},

            dataType: "application/json",

            success : function(response)

            {

                alert(response);

            }

        });

    });

</script>

</body>

</html>

And the Python Code

import sys

import json



def index(req):

    result = {'success':'true','message':'The Command Completed Successfully'};



    data = sys.stdin.read();



    myjson = json.loads(data);



    return str(myjson);

edited May 23 '12 at 13:10

asked May 23 '12 at 10:59

TheMonkeyMan

2,95151833

Presumably, nothing happens? Please tell us the problems you see.

– Martijn Pieters♦
May 23 '12 at 11:03

Are you posting a JSON or a JSON-string which is percentile-encoded?

– UltraInstinct
May 23 '12 at 11:37

I just want it so it shows me what I posted in so I have an idea that it actually works. Insted of it at present returning "null"

– TheMonkeyMan
May 23 '12 at 13:14

@Deano Well, your question first was not very clear. Now you can check the updated version of my answer. It should work.

– VisioN
May 23 '12 at 13:52

Why is there a semicolon after each statement in the python code above? An error, I assume?

– Sudipta Chatterjee
Jan 8 '13 at 23:23

add a comment |

I have got Apache2 Installed and Python working.

I am having a problem though. I have two pages.

One a Python Page and the other an Html Page with JQuery

Can someone please tell me how I can get my ajax post to work correctly.

<html>

<head>



</head>

<body>

<script>

    $(function()

    {

        alert('Im going to start processing');



        $.ajax({

            url: "saveList.py",

            type: "post",

            data: {'param':{"hello":"world"}},

            dataType: "application/json",

            success : function(response)

            {

                alert(response);

            }

        });

    });

</script>

</body>

</html>

And the Python Code

import sys

import json



def index(req):

    result = {'success':'true','message':'The Command Completed Successfully'};



    data = sys.stdin.read();



    myjson = json.loads(data);



    return str(myjson);

edited May 23 '12 at 13:10

asked May 23 '12 at 10:59

TheMonkeyMan

2,95151833

I have got Apache2 Installed and Python working.

I am having a problem though. I have two pages.

One a Python Page and the other an Html Page with JQuery

Can someone please tell me how I can get my ajax post to work correctly.

<html>

<head>



</head>

<body>

<script>

    $(function()

    {

        alert('Im going to start processing');



        $.ajax({

            url: "saveList.py",

            type: "post",

            data: {'param':{"hello":"world"}},

            dataType: "application/json",

            success : function(response)

            {

                alert(response);

            }

        });

    });

</script>

</body>

</html>

And the Python Code

import sys

import json



def index(req):

    result = {'success':'true','message':'The Command Completed Successfully'};



    data = sys.stdin.read();



    myjson = json.loads(data);



    return str(myjson);

jquery python html ajax

edited May 23 '12 at 13:10

asked May 23 '12 at 10:59

TheMonkeyMan

2,95151833

edited May 23 '12 at 13:10

asked May 23 '12 at 10:59

TheMonkeyMan

2,95151833

edited May 23 '12 at 13:10

asked May 23 '12 at 10:59

TheMonkeyMan

2,95151833

asked May 23 '12 at 10:59

TheMonkeyMan

2,95151833

asked May 23 '12 at 10:59

TheMonkeyMan

2,95151833

Presumably, nothing happens? Please tell us the problems you see.

– Martijn Pieters♦
May 23 '12 at 11:03

Are you posting a JSON or a JSON-string which is percentile-encoded?

– UltraInstinct
May 23 '12 at 11:37

I just want it so it shows me what I posted in so I have an idea that it actually works. Insted of it at present returning "null"

– TheMonkeyMan
May 23 '12 at 13:14

@Deano Well, your question first was not very clear. Now you can check the updated version of my answer. It should work.

– VisioN
May 23 '12 at 13:52

Why is there a semicolon after each statement in the python code above? An error, I assume?

– Sudipta Chatterjee
Jan 8 '13 at 23:23

add a comment |

Presumably, nothing happens? Please tell us the problems you see.

– Martijn Pieters♦
May 23 '12 at 11:03

Are you posting a JSON or a JSON-string which is percentile-encoded?

– UltraInstinct
May 23 '12 at 11:37

I just want it so it shows me what I posted in so I have an idea that it actually works. Insted of it at present returning "null"

– TheMonkeyMan
May 23 '12 at 13:14

@Deano Well, your question first was not very clear. Now you can check the updated version of my answer. It should work.

– VisioN
May 23 '12 at 13:52

Why is there a semicolon after each statement in the python code above? An error, I assume?

– Sudipta Chatterjee
Jan 8 '13 at 23:23

Presumably, nothing happens? Please tell us the problems you see.

– Martijn Pieters♦
May 23 '12 at 11:03

Are you posting a JSON or a JSON-string which is percentile-encoded?

– UltraInstinct
May 23 '12 at 11:37

I just want it so it shows me what I posted in so I have an idea that it actually works. Insted of it at present returning "null"

– TheMonkeyMan
May 23 '12 at 13:14

@Deano Well, your question first was not very clear. Now you can check the updated version of my answer. It should work.

– VisioN
May 23 '12 at 13:52

Why is there a semicolon after each statement in the python code above? An error, I assume?

– Sudipta Chatterjee
Jan 8 '13 at 23:23

add a comment |

2 Answers
2

active

oldest

votes

OK, let's move to your updated question.

First, you should pass Ajax data property in string representation. Then, since you mix dataType and contentType properties, change dataType value to "json":

$.ajax({

    url: "saveList.py",

    type: "post",

    data: JSON.stringify({'param':{"hello":"world"}}),

    dataType: "json",

    success: function(response) {

        alert(response);

    }

});

Finally, modify your code a bit to work with JSON request as follows:

#!/usr/bin/python



import sys, json



result = {'success':'true','message':'The Command Completed Successfully'};



myjson = json.load(sys.stdin)

# Do something with 'myjson' object



print 'Content-Type: application/jsonnn'

print json.dumps(result)    # or "json.dump(result, sys.stdout)"

As a result, in the success handler of Ajax request you will receive object with success and message properties.

edited May 23 '12 at 13:51

answered May 23 '12 at 11:20

VisioN

111k24212226

1

He is posting an application/json and not application/x-www-form-urlencoded. His way of reading from stdin is correct (IMO). I suppose problem is elsewhere.

– UltraInstinct
May 23 '12 at 11:34

@Thrustmaster What are you talking about? Default contentType for standard Ajax request is exaclty application/x-www-form-urlencoded. Why do you need to use something else?

– VisioN
May 23 '12 at 11:44

1

OP is (from his code) doing a HTTP/POST with JSON-string in the body of HTTP. The content-type will be application/json which would need to be set using $.ajax({contentType:"application/json"},...). What you suggested up there, is to url-encode JSON string, which, IMO, is not OP is doing (since he is correctly reading from stdin on the server-side for that)

– UltraInstinct
May 23 '12 at 11:50

1

First, are you sure that he reads from stdin correctly? HTTP request is not the same as input from the console. Next, he can easily send not a string but data : { first : 1, next : 2 } and get both first and next with form on server-side. What is the problem? Then, where have you taken that OP sends application/json as content type? Why to do it? OP simply doesn't know how to handle post requests from Ajax with plain Python CGI. I think you overdo it.

– VisioN
May 23 '12 at 11:54

1

I have been searching the web to find how to make cgi recognise raw strings NOT sent from an html form but found this solution..my 3 days of late night sleep came to an end..thank you

– repzero
Nov 27 '15 at 2:04

|
show 3 more comments

You should read json data like this:

#!/usr/bin/env python3



import os

import sys

import json



content_len = int(os.environ["CONTENT_LENGTH"])



req_body = sys.stdin.read(content_len)

my_dict = json.loads(req_body)

With the following code, you can run into problems:

 myjson = json.load(sys.stdin)

or written less succinctly:

requ_body = sys.stdin.read()

my_dict = json.load(requ_body)

That does work for me when my cgi script is on an apache server, but you can't count on that working in general--as I found out when my cgi script was on another server. According to the cgi spec:

RFC 3875                    CGI Version 1.1                 October 2004





4.2.  Request Message-Body



   Request data is accessed by the script in a system-defined method;

   unless defined otherwise, this will be by reading the 'standard

   input' file descriptor or file handle.



      Request-Data   = [ request-body ] [ extension-data ]

      request-body   = <CONTENT_LENGTH>OCTET

      extension-data = *OCTET



   A request-body is supplied with the request if the CONTENT_LENGTH is

   not NULL.  The server MUST make at least that many bytes available

   for the script to read.  The server MAY signal an end-of-file

   condition after CONTENT_LENGTH bytes have been read or it MAY supply

   extension data.  Therefore, the script MUST NOT attempt to read more

   than CONTENT_LENGTH bytes, even if more data is available.  However,

   it is not obliged to read any of the data.

The key line is:

the script MUST NOT attempt to read more
than CONTENT_LENGTH bytes, even if more data is available.

Apparently, apache sends an eof signal to the cgi script immediately after sending the request body to the cgi script, which causes sys.stdin.read() to return. But according to the cgi spec, a server is not required to send an eof signal after the body of the request, and I found that my cgi script was hanging on sys.stdin.read()--when my script was on another server, which eventually caused a timeout error.

Therefore, in order to read in json data in the general case, you should do this:

content_len = int(os.environ["CONTENT_LENGTH"])



req_body = sys.stdin.read(content_len)

my_dict = json.loads(req_body)

The server sets a bunch of environment variables for cgi scripts, which contain header information, one of which is CONTENT_LENGTH.

Here is what a failed curl request looked like when I used myjson = json.load(sys.stdin):

-v      verbose output

-H      specify one header

--data  implicitly specifies a POST request 



Note that curl automatically calculates a Content-Length header 

for you.

~$ curl -v 

> -H 'Content-Type: application/json' 

> --data '{"a": 1, "b": 2}' 

> http://localhost:65451/cgi-bin/1.py



*   Trying ::1...

* TCP_NODELAY set

* Connection failed

* connect to ::1 port 65451 failed: Connection refused

*   Trying 127.0.0.1...

* TCP_NODELAY set

* Connected to localhost (127.0.0.1) port 65451 (#0)

> POST /cgi-bin/1.py HTTP/1.1

> Host: localhost:65451

> User-Agent: curl/7.58.0

> Accept: */*

> Content-Type: application/json

> Content-Length: 16

> 

* upload completely sent off: 16 out of 16 bytes



=== hung here for about 5 seconds ====



< HTTP/1.1 504 Gateway Time-out

< Date: Thu, 08 Mar 2018 17:53:30 GMT

< Content-Type: text/html

< Server: inets/6.4.5

* no chunk, no close, no size. Assume close to signal end

< 

* Closing connection 0

edited Mar 9 '18 at 15:10

answered Mar 9 '18 at 5:58

7stud

29.1k96083

add a comment |

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

OK, let's move to your updated question.

First, you should pass Ajax data property in string representation. Then, since you mix dataType and contentType properties, change dataType value to "json":

$.ajax({

    url: "saveList.py",

    type: "post",

    data: JSON.stringify({'param':{"hello":"world"}}),

    dataType: "json",

    success: function(response) {

        alert(response);

    }

});

Finally, modify your code a bit to work with JSON request as follows:

#!/usr/bin/python



import sys, json



result = {'success':'true','message':'The Command Completed Successfully'};



myjson = json.load(sys.stdin)

# Do something with 'myjson' object



print 'Content-Type: application/jsonnn'

print json.dumps(result)    # or "json.dump(result, sys.stdout)"

As a result, in the success handler of Ajax request you will receive object with success and message properties.

edited May 23 '12 at 13:51

answered May 23 '12 at 11:20

VisioN

111k24212226

1

He is posting an application/json and not application/x-www-form-urlencoded. His way of reading from stdin is correct (IMO). I suppose problem is elsewhere.

– UltraInstinct
May 23 '12 at 11:34

@Thrustmaster What are you talking about? Default contentType for standard Ajax request is exaclty application/x-www-form-urlencoded. Why do you need to use something else?

– VisioN
May 23 '12 at 11:44

1

OP is (from his code) doing a HTTP/POST with JSON-string in the body of HTTP. The content-type will be application/json which would need to be set using $.ajax({contentType:"application/json"},...). What you suggested up there, is to url-encode JSON string, which, IMO, is not OP is doing (since he is correctly reading from stdin on the server-side for that)

– UltraInstinct
May 23 '12 at 11:50

1

First, are you sure that he reads from stdin correctly? HTTP request is not the same as input from the console. Next, he can easily send not a string but data : { first : 1, next : 2 } and get both first and next with form on server-side. What is the problem? Then, where have you taken that OP sends application/json as content type? Why to do it? OP simply doesn't know how to handle post requests from Ajax with plain Python CGI. I think you overdo it.

– VisioN
May 23 '12 at 11:54

1

I have been searching the web to find how to make cgi recognise raw strings NOT sent from an html form but found this solution..my 3 days of late night sleep came to an end..thank you

– repzero
Nov 27 '15 at 2:04

|
show 3 more comments

OK, let's move to your updated question.

First, you should pass Ajax data property in string representation. Then, since you mix dataType and contentType properties, change dataType value to "json":

$.ajax({

    url: "saveList.py",

    type: "post",

    data: JSON.stringify({'param':{"hello":"world"}}),

    dataType: "json",

    success: function(response) {

        alert(response);

    }

});

Finally, modify your code a bit to work with JSON request as follows:

#!/usr/bin/python



import sys, json



result = {'success':'true','message':'The Command Completed Successfully'};



myjson = json.load(sys.stdin)

# Do something with 'myjson' object



print 'Content-Type: application/jsonnn'

print json.dumps(result)    # or "json.dump(result, sys.stdout)"

As a result, in the success handler of Ajax request you will receive object with success and message properties.

edited May 23 '12 at 13:51

answered May 23 '12 at 11:20

VisioN

111k24212226

1

He is posting an application/json and not application/x-www-form-urlencoded. His way of reading from stdin is correct (IMO). I suppose problem is elsewhere.

– UltraInstinct
May 23 '12 at 11:34

@Thrustmaster What are you talking about? Default contentType for standard Ajax request is exaclty application/x-www-form-urlencoded. Why do you need to use something else?

– VisioN
May 23 '12 at 11:44

1

OP is (from his code) doing a HTTP/POST with JSON-string in the body of HTTP. The content-type will be application/json which would need to be set using $.ajax({contentType:"application/json"},...). What you suggested up there, is to url-encode JSON string, which, IMO, is not OP is doing (since he is correctly reading from stdin on the server-side for that)

– UltraInstinct
May 23 '12 at 11:50

1

First, are you sure that he reads from stdin correctly? HTTP request is not the same as input from the console. Next, he can easily send not a string but data : { first : 1, next : 2 } and get both first and next with form on server-side. What is the problem? Then, where have you taken that OP sends application/json as content type? Why to do it? OP simply doesn't know how to handle post requests from Ajax with plain Python CGI. I think you overdo it.

– VisioN
May 23 '12 at 11:54

1

I have been searching the web to find how to make cgi recognise raw strings NOT sent from an html form but found this solution..my 3 days of late night sleep came to an end..thank you

– repzero
Nov 27 '15 at 2:04

|
show 3 more comments

OK, let's move to your updated question.

First, you should pass Ajax data property in string representation. Then, since you mix dataType and contentType properties, change dataType value to "json":

$.ajax({

    url: "saveList.py",

    type: "post",

    data: JSON.stringify({'param':{"hello":"world"}}),

    dataType: "json",

    success: function(response) {

        alert(response);

    }

});

Finally, modify your code a bit to work with JSON request as follows:

#!/usr/bin/python



import sys, json



result = {'success':'true','message':'The Command Completed Successfully'};



myjson = json.load(sys.stdin)

# Do something with 'myjson' object



print 'Content-Type: application/jsonnn'

print json.dumps(result)    # or "json.dump(result, sys.stdout)"

As a result, in the success handler of Ajax request you will receive object with success and message properties.

edited May 23 '12 at 13:51

answered May 23 '12 at 11:20

VisioN

111k24212226

OK, let's move to your updated question.

First, you should pass Ajax data property in string representation. Then, since you mix dataType and contentType properties, change dataType value to "json":

$.ajax({

    url: "saveList.py",

    type: "post",

    data: JSON.stringify({'param':{"hello":"world"}}),

    dataType: "json",

    success: function(response) {

        alert(response);

    }

});

Finally, modify your code a bit to work with JSON request as follows:

#!/usr/bin/python



import sys, json



result = {'success':'true','message':'The Command Completed Successfully'};



myjson = json.load(sys.stdin)

# Do something with 'myjson' object



print 'Content-Type: application/jsonnn'

print json.dumps(result)    # or "json.dump(result, sys.stdout)"

As a result, in the success handler of Ajax request you will receive object with success and message properties.

edited May 23 '12 at 13:51

answered May 23 '12 at 11:20

VisioN

111k24212226

edited May 23 '12 at 13:51

answered May 23 '12 at 11:20

VisioN

111k24212226

answered May 23 '12 at 11:20

VisioN

111k24212226

answered May 23 '12 at 11:20

VisioN

111k24212226

1

He is posting an application/json and not application/x-www-form-urlencoded. His way of reading from stdin is correct (IMO). I suppose problem is elsewhere.

– UltraInstinct
May 23 '12 at 11:34

@Thrustmaster What are you talking about? Default contentType for standard Ajax request is exaclty application/x-www-form-urlencoded. Why do you need to use something else?

– VisioN
May 23 '12 at 11:44

1

OP is (from his code) doing a HTTP/POST with JSON-string in the body of HTTP. The content-type will be application/json which would need to be set using $.ajax({contentType:"application/json"},...). What you suggested up there, is to url-encode JSON string, which, IMO, is not OP is doing (since he is correctly reading from stdin on the server-side for that)

– UltraInstinct
May 23 '12 at 11:50

1

First, are you sure that he reads from stdin correctly? HTTP request is not the same as input from the console. Next, he can easily send not a string but data : { first : 1, next : 2 } and get both first and next with form on server-side. What is the problem? Then, where have you taken that OP sends application/json as content type? Why to do it? OP simply doesn't know how to handle post requests from Ajax with plain Python CGI. I think you overdo it.

– VisioN
May 23 '12 at 11:54

1

I have been searching the web to find how to make cgi recognise raw strings NOT sent from an html form but found this solution..my 3 days of late night sleep came to an end..thank you

– repzero
Nov 27 '15 at 2:04

|
show 3 more comments

1

He is posting an application/json and not application/x-www-form-urlencoded. His way of reading from stdin is correct (IMO). I suppose problem is elsewhere.

– UltraInstinct
May 23 '12 at 11:34

@Thrustmaster What are you talking about? Default contentType for standard Ajax request is exaclty application/x-www-form-urlencoded. Why do you need to use something else?

– VisioN
May 23 '12 at 11:44

1

OP is (from his code) doing a HTTP/POST with JSON-string in the body of HTTP. The content-type will be application/json which would need to be set using $.ajax({contentType:"application/json"},...). What you suggested up there, is to url-encode JSON string, which, IMO, is not OP is doing (since he is correctly reading from stdin on the server-side for that)

– UltraInstinct
May 23 '12 at 11:50

1

First, are you sure that he reads from stdin correctly? HTTP request is not the same as input from the console. Next, he can easily send not a string but data : { first : 1, next : 2 } and get both first and next with form on server-side. What is the problem? Then, where have you taken that OP sends application/json as content type? Why to do it? OP simply doesn't know how to handle post requests from Ajax with plain Python CGI. I think you overdo it.

– VisioN
May 23 '12 at 11:54

1

I have been searching the web to find how to make cgi recognise raw strings NOT sent from an html form but found this solution..my 3 days of late night sleep came to an end..thank you

– repzero
Nov 27 '15 at 2:04

He is posting an application/json and not application/x-www-form-urlencoded. His way of reading from stdin is correct (IMO). I suppose problem is elsewhere.

– UltraInstinct
May 23 '12 at 11:34

@Thrustmaster What are you talking about? Default contentType for standard Ajax request is exaclty application/x-www-form-urlencoded. Why do you need to use something else?

– VisioN
May 23 '12 at 11:44

OP is (from his code) doing a HTTP/POST with JSON-string in the body of HTTP. The content-type will be application/json which would need to be set using $.ajax({contentType:"application/json"},...). What you suggested up there, is to url-encode JSON string, which, IMO, is not OP is doing (since he is correctly reading from stdin on the server-side for that)

– UltraInstinct
May 23 '12 at 11:50

First, are you sure that he reads from stdin correctly? HTTP request is not the same as input from the console. Next, he can easily send not a string but data : { first : 1, next : 2 } and get both first and next with form on server-side. What is the problem? Then, where have you taken that OP sends application/json as content type? Why to do it? OP simply doesn't know how to handle post requests from Ajax with plain Python CGI. I think you overdo it.

– VisioN
May 23 '12 at 11:54

I have been searching the web to find how to make cgi recognise raw strings NOT sent from an html form but found this solution..my 3 days of late night sleep came to an end..thank you

– repzero
Nov 27 '15 at 2:04

|
show 3 more comments

You should read json data like this:

#!/usr/bin/env python3



import os

import sys

import json



content_len = int(os.environ["CONTENT_LENGTH"])



req_body = sys.stdin.read(content_len)

my_dict = json.loads(req_body)

With the following code, you can run into problems:

 myjson = json.load(sys.stdin)

or written less succinctly:

requ_body = sys.stdin.read()

my_dict = json.load(requ_body)

RFC 3875                    CGI Version 1.1                 October 2004





4.2.  Request Message-Body



   Request data is accessed by the script in a system-defined method;

   unless defined otherwise, this will be by reading the 'standard

   input' file descriptor or file handle.



      Request-Data   = [ request-body ] [ extension-data ]

      request-body   = <CONTENT_LENGTH>OCTET

      extension-data = *OCTET



   A request-body is supplied with the request if the CONTENT_LENGTH is

   not NULL.  The server MUST make at least that many bytes available

   for the script to read.  The server MAY signal an end-of-file

   condition after CONTENT_LENGTH bytes have been read or it MAY supply

   extension data.  Therefore, the script MUST NOT attempt to read more

   than CONTENT_LENGTH bytes, even if more data is available.  However,

   it is not obliged to read any of the data.

The key line is:

the script MUST NOT attempt to read more
than CONTENT_LENGTH bytes, even if more data is available.

Therefore, in order to read in json data in the general case, you should do this:

content_len = int(os.environ["CONTENT_LENGTH"])



req_body = sys.stdin.read(content_len)

my_dict = json.loads(req_body)

The server sets a bunch of environment variables for cgi scripts, which contain header information, one of which is CONTENT_LENGTH.

Here is what a failed curl request looked like when I used myjson = json.load(sys.stdin):

-v      verbose output

-H      specify one header

--data  implicitly specifies a POST request 



Note that curl automatically calculates a Content-Length header 

for you.

~$ curl -v 

> -H 'Content-Type: application/json' 

> --data '{"a": 1, "b": 2}' 

> http://localhost:65451/cgi-bin/1.py



*   Trying ::1...

* TCP_NODELAY set

* Connection failed

* connect to ::1 port 65451 failed: Connection refused

*   Trying 127.0.0.1...

* TCP_NODELAY set

* Connected to localhost (127.0.0.1) port 65451 (#0)

> POST /cgi-bin/1.py HTTP/1.1

> Host: localhost:65451

> User-Agent: curl/7.58.0

> Accept: */*

> Content-Type: application/json

> Content-Length: 16

> 

* upload completely sent off: 16 out of 16 bytes



=== hung here for about 5 seconds ====



< HTTP/1.1 504 Gateway Time-out

< Date: Thu, 08 Mar 2018 17:53:30 GMT

< Content-Type: text/html

< Server: inets/6.4.5

* no chunk, no close, no size. Assume close to signal end

< 

* Closing connection 0

edited Mar 9 '18 at 15:10

answered Mar 9 '18 at 5:58

7stud

29.1k96083

add a comment |

You should read json data like this:

#!/usr/bin/env python3



import os

import sys

import json



content_len = int(os.environ["CONTENT_LENGTH"])



req_body = sys.stdin.read(content_len)

my_dict = json.loads(req_body)

With the following code, you can run into problems:

 myjson = json.load(sys.stdin)

or written less succinctly:

requ_body = sys.stdin.read()

my_dict = json.load(requ_body)

RFC 3875                    CGI Version 1.1                 October 2004





4.2.  Request Message-Body



   Request data is accessed by the script in a system-defined method;

   unless defined otherwise, this will be by reading the 'standard

   input' file descriptor or file handle.



      Request-Data   = [ request-body ] [ extension-data ]

      request-body   = <CONTENT_LENGTH>OCTET

      extension-data = *OCTET



   A request-body is supplied with the request if the CONTENT_LENGTH is

   not NULL.  The server MUST make at least that many bytes available

   for the script to read.  The server MAY signal an end-of-file

   condition after CONTENT_LENGTH bytes have been read or it MAY supply

   extension data.  Therefore, the script MUST NOT attempt to read more

   than CONTENT_LENGTH bytes, even if more data is available.  However,

   it is not obliged to read any of the data.

The key line is:

the script MUST NOT attempt to read more
than CONTENT_LENGTH bytes, even if more data is available.

Therefore, in order to read in json data in the general case, you should do this:

content_len = int(os.environ["CONTENT_LENGTH"])



req_body = sys.stdin.read(content_len)

my_dict = json.loads(req_body)

The server sets a bunch of environment variables for cgi scripts, which contain header information, one of which is CONTENT_LENGTH.

Here is what a failed curl request looked like when I used myjson = json.load(sys.stdin):

-v      verbose output

-H      specify one header

--data  implicitly specifies a POST request 



Note that curl automatically calculates a Content-Length header 

for you.

~$ curl -v 

> -H 'Content-Type: application/json' 

> --data '{"a": 1, "b": 2}' 

> http://localhost:65451/cgi-bin/1.py



*   Trying ::1...

* TCP_NODELAY set

* Connection failed

* connect to ::1 port 65451 failed: Connection refused

*   Trying 127.0.0.1...

* TCP_NODELAY set

* Connected to localhost (127.0.0.1) port 65451 (#0)

> POST /cgi-bin/1.py HTTP/1.1

> Host: localhost:65451

> User-Agent: curl/7.58.0

> Accept: */*

> Content-Type: application/json

> Content-Length: 16

> 

* upload completely sent off: 16 out of 16 bytes



=== hung here for about 5 seconds ====



< HTTP/1.1 504 Gateway Time-out

< Date: Thu, 08 Mar 2018 17:53:30 GMT

< Content-Type: text/html

< Server: inets/6.4.5

* no chunk, no close, no size. Assume close to signal end

< 

* Closing connection 0

edited Mar 9 '18 at 15:10

answered Mar 9 '18 at 5:58

7stud

29.1k96083

add a comment |

You should read json data like this:

#!/usr/bin/env python3



import os

import sys

import json



content_len = int(os.environ["CONTENT_LENGTH"])



req_body = sys.stdin.read(content_len)

my_dict = json.loads(req_body)

With the following code, you can run into problems:

 myjson = json.load(sys.stdin)

or written less succinctly:

requ_body = sys.stdin.read()

my_dict = json.load(requ_body)

RFC 3875                    CGI Version 1.1                 October 2004





4.2.  Request Message-Body



   Request data is accessed by the script in a system-defined method;

   unless defined otherwise, this will be by reading the 'standard

   input' file descriptor or file handle.



      Request-Data   = [ request-body ] [ extension-data ]

      request-body   = <CONTENT_LENGTH>OCTET

      extension-data = *OCTET



   A request-body is supplied with the request if the CONTENT_LENGTH is

   not NULL.  The server MUST make at least that many bytes available

   for the script to read.  The server MAY signal an end-of-file

   condition after CONTENT_LENGTH bytes have been read or it MAY supply

   extension data.  Therefore, the script MUST NOT attempt to read more

   than CONTENT_LENGTH bytes, even if more data is available.  However,

   it is not obliged to read any of the data.

The key line is:

the script MUST NOT attempt to read more
than CONTENT_LENGTH bytes, even if more data is available.

Therefore, in order to read in json data in the general case, you should do this:

content_len = int(os.environ["CONTENT_LENGTH"])



req_body = sys.stdin.read(content_len)

my_dict = json.loads(req_body)

The server sets a bunch of environment variables for cgi scripts, which contain header information, one of which is CONTENT_LENGTH.

Here is what a failed curl request looked like when I used myjson = json.load(sys.stdin):

-v      verbose output

-H      specify one header

--data  implicitly specifies a POST request 



Note that curl automatically calculates a Content-Length header 

for you.

~$ curl -v 

> -H 'Content-Type: application/json' 

> --data '{"a": 1, "b": 2}' 

> http://localhost:65451/cgi-bin/1.py



*   Trying ::1...

* TCP_NODELAY set

* Connection failed

* connect to ::1 port 65451 failed: Connection refused

*   Trying 127.0.0.1...

* TCP_NODELAY set

* Connected to localhost (127.0.0.1) port 65451 (#0)

> POST /cgi-bin/1.py HTTP/1.1

> Host: localhost:65451

> User-Agent: curl/7.58.0

> Accept: */*

> Content-Type: application/json

> Content-Length: 16

> 

* upload completely sent off: 16 out of 16 bytes



=== hung here for about 5 seconds ====



< HTTP/1.1 504 Gateway Time-out

< Date: Thu, 08 Mar 2018 17:53:30 GMT

< Content-Type: text/html

< Server: inets/6.4.5

* no chunk, no close, no size. Assume close to signal end

< 

* Closing connection 0

edited Mar 9 '18 at 15:10

answered Mar 9 '18 at 5:58

7stud

29.1k96083

You should read json data like this:

#!/usr/bin/env python3



import os

import sys

import json



content_len = int(os.environ["CONTENT_LENGTH"])



req_body = sys.stdin.read(content_len)

my_dict = json.loads(req_body)

With the following code, you can run into problems:

 myjson = json.load(sys.stdin)

or written less succinctly:

requ_body = sys.stdin.read()

my_dict = json.load(requ_body)

RFC 3875                    CGI Version 1.1                 October 2004





4.2.  Request Message-Body



   Request data is accessed by the script in a system-defined method;

   unless defined otherwise, this will be by reading the 'standard

   input' file descriptor or file handle.



      Request-Data   = [ request-body ] [ extension-data ]

      request-body   = <CONTENT_LENGTH>OCTET

      extension-data = *OCTET



   A request-body is supplied with the request if the CONTENT_LENGTH is

   not NULL.  The server MUST make at least that many bytes available

   for the script to read.  The server MAY signal an end-of-file

   condition after CONTENT_LENGTH bytes have been read or it MAY supply

   extension data.  Therefore, the script MUST NOT attempt to read more

   than CONTENT_LENGTH bytes, even if more data is available.  However,

   it is not obliged to read any of the data.

The key line is:

the script MUST NOT attempt to read more
than CONTENT_LENGTH bytes, even if more data is available.

Therefore, in order to read in json data in the general case, you should do this:

content_len = int(os.environ["CONTENT_LENGTH"])



req_body = sys.stdin.read(content_len)

my_dict = json.loads(req_body)

The server sets a bunch of environment variables for cgi scripts, which contain header information, one of which is CONTENT_LENGTH.

Here is what a failed curl request looked like when I used myjson = json.load(sys.stdin):

-v      verbose output

-H      specify one header

--data  implicitly specifies a POST request 



Note that curl automatically calculates a Content-Length header 

for you.

~$ curl -v 

> -H 'Content-Type: application/json' 

> --data '{"a": 1, "b": 2}' 

> http://localhost:65451/cgi-bin/1.py



*   Trying ::1...

* TCP_NODELAY set

* Connection failed

* connect to ::1 port 65451 failed: Connection refused

*   Trying 127.0.0.1...

* TCP_NODELAY set

* Connected to localhost (127.0.0.1) port 65451 (#0)

> POST /cgi-bin/1.py HTTP/1.1

> Host: localhost:65451

> User-Agent: curl/7.58.0

> Accept: */*

> Content-Type: application/json

> Content-Length: 16

> 

* upload completely sent off: 16 out of 16 bytes



=== hung here for about 5 seconds ====



< HTTP/1.1 504 Gateway Time-out

< Date: Thu, 08 Mar 2018 17:53:30 GMT

< Content-Type: text/html

< Server: inets/6.4.5

* no chunk, no close, no size. Assume close to signal end

< 

* Closing connection 0

edited Mar 9 '18 at 15:10

answered Mar 9 '18 at 5:58

7stud

29.1k96083

edited Mar 9 '18 at 15:10

answered Mar 9 '18 at 5:58

7stud

29.1k96083

answered Mar 9 '18 at 5:58

7stud

29.1k96083

answered Mar 9 '18 at 5:58

7stud

29.1k96083

add a comment |

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