"location" : null // this is not really an array it's a null object
"location" : []   // this is an empty array

It looks like this API returns null when there is no location defined - instead of returning an empty array, not too unusual really - but they should tell you if they're going to do this.

Simply:

Copyjson.loads(request.POST.get('mydata', '{}'))

Or:

Copydata = json.loads(request.POST['mydata']) if 'mydata' in request.POST else {}

Or:

Copyif 'mydata' in request.POST:
    data = json.loads(request.POST['mydata'])
else:
    data = {} # or data = None

Modify your reader script to this:

with open('favoriteColor.json') as inFile:
    try: 
         colors = json.load(inFile)
    except ValueError: 
         colors = []

This attempts to load the file as a json. If it fails due to a value error, we know that this is because the json is empty. Therefore we can just assign colors to an empty list. It is also preferable to use the "with" construct to load files since it closes them automatically.

You have to use os.path.getsize(path) to find file size of a file.
You do not have to read file at all.
If JSON file is just 2 bytes, "[]" or "{}", it is an empty JSON object.

Based on some JSON usage principles, in this particular case it is sane and safe to presume that a 2 bytes long JSON string is an empty string, array or object ("", [], {}). A two digits number may be a valid JSON string but it is not what JSON is used for (you can use JSON library to load a single value like you can use a big crane to lift an egg).

If this [file size] does not fulfill your requirements you have to read the first 2 bytes and check if they are equal to '[]':

with open(filename, 'rb') as file:
    if file.read(2) != '[]':
        file.seek(0)  # it may be redundant but it does not hurt
        json.load(file)

You're misunderstanding how in works. in checks to see if a key exists in a dictionary, it does not index into a dictionary. That's what the square brackets do.

if 'title_jpn' in json_data['gmetadata'][0] is not "":

The above line will not evaluate as you expect. It should be.

if json_data['gmetadata'][0]['title_jpn'] is not "":

This can be further simplified because empty strings '' always evaluate to False in python. So instead of checking if the string is not empty, just check if it has any value at all like the following:

if json_data['gmetadata'][0]['title_jpn']:

If you're trying to guard against the fact that title_jpn might be optional and not always exist, you need to do two conditions in your if statement (which I think is what you were originally trying to do):

if 'title_jpn' in json_data['gmetadata'][0] and json_data['gmetadata'][0]['title_jpn']:

The above line first checks if the title_jpn key is present before trying to check if it's value is empty. This can be further simplified using the dictionary .get() method which allows you to supply a default.

if json_data['gmetadata'][0].get('title_jpn', None):

The above will check if title_jpn is in the dictionary and return the value if it does, or None as a default if it does not. Since None is interpreted as False in python, the if block will not run, which is the desired behaviour.

dict.get(key, default=None)

However, since .get() automatically sets the default value to None, you can simply do the following.

if json_data['gmetadata'][0].get('title_jpn'):

If the list of "emailAddresses" is empty, the for loop doesn't get executed. Accordingly print("boo") neither.

You need to check the list first, before iterate through the list:

results = response.json()["data"]
for item in results:
    emails = item["contacts"]["emailAddresses"]
    if emails:
        for email in emails:
            print(email)
    else:
        print("boo")

JSON is a string representation of data, such as lists and dictionaries. You don't append to the JSON, you append to the original data and then dump it.

Also, you don't use append() with dictionaries, it's used with lists.

data = {} # This is a dictionary
data["a"] = "1"; # Add an item to the dictionary
json_data = json.dumps(data) # Convert the dictionary to a JSON string
print(json_data)

If you have a large number of null values that you want to change to empty array when using JSON#stringify, you can use a replace function (2nd param):

JSON.stringify(value[, replacer[, space]])

The function receives the key and the value, and you can decide, which value you want to return.

var data = {
  var1: null,
  var2: "someString",
  var3: 1.3
};

var reslut = JSON.stringify(data, function(key, value) {
  if (value === null) {
    return [];
  }
  return value;
});

console.log(reslut);

Check both, the key existence and its length:

import json, sys

obj=json.load(sys.stdin)

if not 'results' in obj or len(obj['results']) == 0:
    exit(0)
else:
    exit(1)

You can try the below

data = {
  "_class": "org.jenkinsci.plugins.workflow.job.WorkflowRun",
  "actions": [
    {
      "date": "xyz",
      "lastBuiltRevision": {
        "branch": [
          {
            "SHA1": "5213affe970c86cd6e13b9d0e52515ac53f46aae",
            "name": "feature/demo"
          }
        ]
      }
    },
    {
      
    },
    {
      
    },
    {
      
    },
    {
      "date": "abc",
      "lastBuiltRevision": {
        "branch": [
          {
            "SHA1": "ca7972a32cc28304c22c98ceabf8e349fbf1a100",
            "name": "refs/remotes/xyz/feature/demo_xyz"
          }
        ]
      }
    },
    {
      "_class": "org.jenkinsci.plugins.displayurlapi.actions.RunDisplayAction"
    },
    {
      "_class": "org.jenkinsci.plugins.pipeline.modeldefinition.actions.RestartDeclarativePipelineAction"
    },
    {
      
    },
    {
      "_class": "org.jenkinsci.plugins.workflow.job.views.FlowGraphAction"
    },
    {
      
    },
    {
      
    },
    {
      
    },
    {
      
    },
    {
      "_class": "org.marvelution.jji.export.ParentAction"
    }
  ]
}
branch_name="refs/remotes/xyz/feature/demo_xyz"
data['actions'] = [x for x in data['actions'] if x and 'lastBuiltRevision' in x and x['lastBuiltRevision']['branch'][0]['name'] == branch_name]
for x in data.get('actions'):
  entry = x['lastBuiltRevision']['branch'][0]
  print(f'Name: {entry["name"]}, SHA1: {entry["SHA1"]}')

output

Name: refs/remotes/xyz/feature/demo_xyz, SHA1: ca7972a32cc28304c22c98ceabf8e349fbf1a100

tweet is a string, you can't use it as a dictionary, you have to use json.loads:

tweet = json.loads(line) # no `json.dumps`
print tweet
tweet["sentiment"] = raw_input('provide input (sentiment): ') # error was here
tweets_data.append(tweet)

Currently the error is when you try to set a new field, but you use try .. except which goes to continue and you miss it completely. A step-through in the debugger would have solved it easily.

If you still want to use json.dumps use it AFTER you set fields in the dictionary.