Parse JSON with missing fields using cjson Lua module in Openresty - json
I am trying to parse a json payload sent via a POST request to a NGINX/Openresty location. To do so, I combined Openresty's content_by_lua_block with its cjson module like this:
# other locations above
location /test {
content_by_lua_block {
ngx.req.read_body()
local data_string = ngx.req.get_body_data()
local cjson = require "cjson.safe"
local json = cjson.decode(data_string)
local endpoint_name = json['endpoint']['name']
local payload = json['payload']
local source_address = json['source_address']
local submit_date = json['submit_date']
ngx.say('Parsed')
}
}
Parsing sample data containing all required fields works as expected. A correct JSON object could look like this:
{
"payload": "the payload here",
"submit_date": "2018-08-17 16:31:51",
},
"endpoint": {
"name": "name of the endpoint here"
},
"source_address": "source address here",
}
However, a user might POST a differently formatted JSON object to the location. Assume a simple JSON document like
{
"username": "JohnDoe",
"password": "password123"
}
not containing the desired fields/keys.
According to the cjson module docs, using cjson (without its safe mode) will raise an error if invalid data is encountered. To prevent any errors being raised, I decided to use its safe mode by importing cjson.safe. This should return nil for invalid data and provide the error message instead of raising the error:
The cjson module will throw an error during JSON conversion if any invalid data is encountered. [...]
The cjson.safe module behaves identically to the cjson module, except when errors are encountered during JSON conversion. On error, the cjson_safe.encode and cjson_safe.decode functions will return nil followed by the error message.
However, I do not encounter any different error handling behavior in my case and the following traceback is shown in Openresty's error.log file:
2021/04/30 20:33:16 [error] 6176#6176: *176 lua entry thread aborted: runtime error: content_by_lua(samplesite:50):16: attempt to index field 'endpoint' (a nil value)
Which in turn results in an Internal Server Error:
<html>
<head><title>500 Internal Server Error</title></head>
<body>
<center><h1>500 Internal Server Error</h1></center>
<hr><center>openresty</center>
</body>
</html>
I think a workaround might be writing a dedicated function for parsing the JSON data and calling it with pcall() to catch any errors. However, this would make the safe mode kind of useless. What am I missing here?
Your “simple JSON document” is a valid JSON document. The error you are facing is not related to cjson, it's a standard Lua error:
resty -e 'local t = {foo = 1}; print(t["foo"]); print(t["foo"]["bar"])'
1
ERROR: (command line -e):1: attempt to index field 'foo' (a number value)
stack traceback:
...
“Safeness” of cjson.safe is about parsing of malformed documents:
cjson module raises an error:
resty -e 'print(require("cjson").decode("[1, 2, 3"))'
ERROR: (command line -e):1: Expected comma or array end but found T_END at character 9
stack traceback:
...
cjson.safe returns nil and an error message:
resty -e 'print(require("cjson.safe").decode("[1, 2, 3"))'
nilExpected comma or array end but found T_END at character 9
Related
Robot Framework bypass HTTPError: 400 Client Error: Bad Request
I have a request which tend to upload a file, if a file with the same name already exists it throws a message that the file already exists. This can be considered as expected result and even though the error I would the test to pass as it is.
This is the code I am using:
Create Session mysession ${test_env}
&{headers} Create Dictionary Content-Type=application/json; charset=utf-8 Authorization=${token}
${json}= Catenate { "FileName": "File.txt", "Content": "PD94bWwg..", "UserId": "email.com" }
${value} Set Variable 2
${value} Convert To Integer ${value}
${json}= Evaluate json.loads('''${json}''') json
#Set To Dictionary ${json["FileName"]}
${json}= Evaluate json.dumps(${json}) json
${resp} POST url=${test_env}/api/nt data=${json} headers=${headers}
${log}= Log To Console ${resp.status_code} 400
Log To Console ${resp.content}
Status Should Be expected_status=any
The test stops at the POST request and does not want to read the expected_status=any and consider the test as pass.
I would appreciate any hints on how to make it pass.
Below code will verify the 400 error and will continue further execution
Run Keyword And Expect Error HTTPError: 400* POST url=${test_env}/api/nt data=${json} headers=${headers}
Error in fromJSON(commandArgs(1)) : unexpected character '''
I am calling a R script from Scala by using scala.sys.process. This script takes a command line argument in JSON format and processes it. I am using rjson's fromJSON function to store the JSON in a list.
This works very fine when I execute the R script from the command line:
$ ./dfChargerFlink.R '{"Id":"1","value":"ABC"}'
But when I call it from scala, I get the following error:
Error in fromJSON(commandArgs(1)) : unexpected character '''
Execution halted
This is the code I am using:
val shellCommand = "./dfChargerFlink.R '"+arg+"'"
return shellCommand !!
where arg is the JSON string.
You can notice that I have appended " ' " to both the sides of the JSON string as if I don't, I get this error:
Error in fromJSON(commandArgs(1)) : unclosed string
Execution halted
How can this be solved? Is it some bug?
Json Type Provider: Parsing Valid Json Fails
I have the following code block in my REPL
#r "../packages/FSharp.Data.2.2.1/lib/net40/FSharp.Data.dll"
open FSharp.Data
[<Literal>]
let uri = "http://www.google.com/finance/option_chain?q=AAPL&output=json"
type OptionChain = JsonProvider<uri>
When I run it, FSI is returning
Error 1 The type provider 'ProviderImplementation.JsonProvider'
reported an error: Cannot read sample JSON from
'http://www.google.com/finance/option_chain?q=AAPL&output=json':
Invalid JSON starting at character 1, snippet =
---- {expiry:{y:2
----- json =
------ {expiry:{y:2015,m:5,d:8},expirations: [{y:2015,m:5,d:8},{y:2015,m:5,d:15},
This json is valid according to two other sites. Is it a bug in the TP?
The output isn't valid JSON because some keys are not quoted.
{expiry:{y:2015,m:5,d:8},expirations:[{y:2015,m:5,d:8},{y:2015,m:5,d:15},{y:2015,m:5,d:22},{y:2015,m:5,d:29},{y:2015,m:6,d:5},{y:2015,m:6,d:12},{y:2015,m:6,d:19},{y:2015,m:6,d:26},{y:2015,m:7,d:17},{y:2015,m:8,d:21},{y:2015,m:10,d:16},{y:2016,m:1,d:15},{y:2017,m:1,d:20}],
puts:[{cid:"43623726334021",s:"AAPL150508P00085000",e:"OPRA",p:"-",c:"-",b:"-",a:"-",oi:"-",vol:"-",strike:"85.00",expiry:"May 8, 2015"},
...
Lua-cjson -> require("cjson") successful, then errors when calling cjson.encode
I'm trying to encode/decode JSON in Lua using CJSON. I downloaded lua-cjson using Luarocks (http://www.kyne.com.au/~mark/software/lua-cjson-manual.html).
In the Lua interpreter, I'm using an example from the cjson manual:
> local cjson = require "cjson"
> value = { true, { foo = "bar" } }
> json_text = cjson.encode(value)
stdin:1: attempt to index a nil value (global 'cjson')
stack traceback:
stdin:1: in main chunk
[C]: in ?
I know that cjson is being found, because if I were to do ' require "foobar" ', Lua would error. It's just not able to use the module. Any help would be appreciated.
Each line in an interactive session is a separate chunk. So, the local variable created in line 1 no longer exists in the next lines. Note how the error message mentions a global variable. Try removing local.
Error in fromJSON(paste(raw.data, collapse = "")) : unclosed string
I am using the R package rjson to download weather data from Wunderground.com. Often I leave the program to run and there are no problems, with the data being collected fine. However, often the program stops running and I get the following error message: Error in fromJSON(paste(raw.data, collapse = "")) : unclosed string In addition: Warning message: In readLines(conn, n = -1L, ok = TRUE) : incomplete final line found on 'http://api.wunderground.com/api/[my_API_code]/history_20121214pws:1/q/pws:IBIRMING7.json' Does anyone know what this means, and how I can avoid it since it stops my program from collecting data as I would like? Many thanks, Ben
I can recreate your error message using the rjson package.
Here's an example that works.
rjson::fromJSON('{"x":"a string"}')
# $x
# [1] "a string"
If we omit a double quote from the value of x, then we get the error message.
rjson::fromJSON('{"x":"a string}')
# Error in rjson::fromJSON("{\"x\":\"a string}") : unclosed string
The RJSONIO package behaves slightly differently. Rather than throwing an error, it silently returns a NULL value.
RJSONIO::fromJSON('{"x":"a string}')
# $x
# NULL