Json handling in ROBOT - json

Question

I have a Json file in which there is a field which I need to edit and save the file for next usage.
But the field which I need to edit is as shown below,
The value I need to assign fr the field is generated Randomly in run time which i'll be capturing in a variable and pass it to this json specific key "dp" then save the json.
The saved json will be used for REST POST url.
{
"p": "10",
"v": 100,
"vt": [
{
"dp": "Field to be edited"(integer value) ,
]
}

Answer 1

The simplest solution would be to write a python keyword that can change the value for you. However, you can solve this with robot keywords by performing the following steps:
convert the JSON string to a dictionary
modify the dictionary
convert the dictionary back to a JSON string
Convert the JSON string to a dictionary
Python has a module (json) for working with JSON data. You can use the evaluate keyword to convert your JSON string to a python dictionary using the loads (load string) method of that module.
Assuming your JSON data is in a robot variable named ${json_string}, you can convert it to a python dictionary like this:
${json}= evaluate json.loads('''${json_string}''') json
With the above, ${json} now holds a reference to a dictionary that contains all of the json data.
Modify the dictionary
The Collections library that comes with robot has a keyword named set to dictionary which can be used to set the value of a dictionary element. In this case, you need to change the value of a dictionary nested inside the vt element of the JSON object. We can reference that nested dictionary using robot's extended variable syntax.
For example:
set to dictionary ${json["vt"]} dp=the new value
With that, ${json} now has the new value. However, it is still a python dictionary rather than JSON data, so there's one more step.
Convert the dictionary back to JSON
Converting the dictionary back to JSON is the reverse of the first step. Namely, use the dumps (dump string) method of the json module:
${json_string}= evaluate json.dumps(${json}) json
With that, ${json_string} will contain a valid JSON string with the modified data.
Complete example
The following is a complete working example. The JSON string will be printed before and after the substitution of the new value:
*** Settings ***
Library Collections
*** Test Cases ***
Example
${json_string}= catenate
... {
... "p": "10",
... "v": 100,
... "vt": {
... "dp": "Field to be edited"
... }
... }
log to console \nOriginal JSON:\n${json_string}
${json}= evaluate json.loads('''${json_string}''') json
set to dictionary ${json["vt"]} dp=the new value
${json_string}= evaluate json.dumps(${json}) json
log to console \nNew JSON string:\n${json_string}

Answer 2

For reading and writing data to and from file I am using OperatingSystem library
${json} Get Binary File ${json_path}nameOfJsonFile.json
It works for me on API testing, to read .json and POST, like here
*** Settings ***
Library Collections
Library ExtendedRequestsLibrary
Library OperatingSystem
*** Variables ***
${uri} https://blabla.com/service/
${json_path} C:/home/user/project/src/json/
*** Test Cases ***
Robot Test Case
Create Session alias ${uri}
&{headers} Create Dictionary Content-Type=application/json; charset=utf-8
${json} Get Binary File ${json_path}nameOfJsonFile.json
${resp} Post Request alias data=${json} headers=${headers}
Should Be Equal As Strings ${resp.status_code} 200

Answer 3

For integer values in JSON, the other answers did not work for me.
This worked:
${json}= Catenate { "p": "10", "v": 100, "vt": { "dp": "Field to be edited" } }
${value} Set Variable 2 #the value you want
${value} Convert To Integer ${value}
${json}= Evaluate json.loads('''${json}''') json
Set To Dictionary ${json["vt"]} dp=${value}
${json}= Evaluate json.dumps(${json}) json
Log ${json}
Convert To Integer was required, otherwise the value is still in string "${value}"