Develop Reference

Changing value of a value in a dictionary within a list within a dictionary

I have a json like:
pd = {
"RP": [
{
"Name": "PD",
"Value": "qwe"
},
{
"Name": "qwe",
"Value": "change"
}
],
"RFN": [
"All"
],
"RIT": [
{
"ID": "All",
"IDT": "All"
}
]
}
I am trying to change the value change to changed. This is a dictionary within a list which is within another dictionary. Is there a better/ more efficient/pythonic way to do this than what I did below:
for key, value in pd.items():
ls = pd[key]
for d in ls:
if type(d) == dict:
for k,v in d.items():
if v == 'change':
pd[key][ls.index(d)][k] = "changed"
This seems pretty inefficient due to the amount of times I am parsing through the data.

String replacement could work if you don't want to write depth/breadth-first search.
>>> import json
>>> json.loads(json.dumps(pd).replace('"Value": "change"', '"Value": "changed"'))
{'RP': [{'Name': 'PD', 'Value': 'qwe'}, {'Name': 'qwe', 'Value': 'changed'}],
'RFN': ['All'],
'RIT': [{'ID': 'All', 'IDT': 'All'}]}

Referencing Values in a List (syntax issue?) [duplicate]

I wrote some code to get data from a web API. I was able to parse the JSON data from the API, but the result I gets looks quite complex. Here is one example:
>>> my_json
{'name': 'ns1:timeSeriesResponseType', 'declaredType': 'org.cuahsi.waterml.TimeSeriesResponseType', 'scope': 'javax.xml.bind.JAXBElement$GlobalScope', 'value': {'queryInfo': {'creationTime': 1349724919000, 'queryURL': 'http://waterservices.usgs.gov/nwis/iv/', 'criteria': {'locationParam': '[ALL:103232434]', 'variableParam': '[00060, 00065]'}, 'note': [{'value': '[ALL:103232434]', 'title': 'filter:sites'}, {'value': '[mode=LATEST, modifiedSince=null]', 'title': 'filter:timeRange'}, {'value': 'sdas01', 'title': 'server'}]}}, 'nil': False, 'globalScope': True, 'typeSubstituted': False}
Looking through this data, I can see the specific data I want: the 1349724919000 value that is labelled as 'creationTime'.
How can I write code that directly gets this value?
I don't need any searching logic to find this value. I can see what I need when I look at the response; I just need to know how to translate that into specific code to extract the specific value, in a hard-coded way. I read some tutorials, so I understand that I need to use [] to access elements of the nested lists and dictionaries; but I can't figure out exactly how it works for a complex case.
More generally, how can I figure out what the "path" is to the data, and write the code for it?

For reference, let's see what the original JSON would look like, with pretty formatting:
>>> print(json.dumps(my_json, indent=4))
{
"name": "ns1:timeSeriesResponseType",
"declaredType": "org.cuahsi.waterml.TimeSeriesResponseType",
"scope": "javax.xml.bind.JAXBElement$GlobalScope",
"value": {
"queryInfo": {
"creationTime": 1349724919000,
"queryURL": "http://waterservices.usgs.gov/nwis/iv/",
"criteria": {
"locationParam": "[ALL:103232434]",
"variableParam": "[00060, 00065]"
},
"note": [
{
"value": "[ALL:103232434]",
"title": "filter:sites"
},
{
"value": "[mode=LATEST, modifiedSince=null]",
"title": "filter:timeRange"
},
{
"value": "sdas01",
"title": "server"
}
]
}
},
"nil": false,
"globalScope": true,
"typeSubstituted": false
}
That lets us see the structure of the data more clearly.
In the specific case, first we want to look at the corresponding value under the 'value' key in our parsed data. That is another dict; we can access the value of its 'queryInfo' key in the same way, and similarly the 'creationTime' from there.
To get the desired value, we simply put those accesses one after another:
my_json['value']['queryInfo']['creationTime'] # 1349724919000

I just need to know how to translate that into specific code to extract the specific value, in a hard-coded way.
If you access the API again, the new data might not match the code's expectation. You may find it useful to add some error handling. For example, use .get() to access dictionaries in the data, rather than indexing:
name = my_json.get('name') # will return None if 'name' doesn't exist
Another way is to test for a key explicitly:
if 'name' in resp_dict:
name = resp_dict['name']
else:
pass
However, these approaches may fail if further accesses are required. A placeholder result of None isn't a dictionary or a list, so attempts to access it that way will fail again (with TypeError). Since "Simple is better than complex" and "it's easier to ask for forgiveness than permission", the straightforward solution is to use exception handling:
try:
creation_time = my_json['value']['queryInfo']['creationTime']
except (TypeError, KeyError):
print("could not read the creation time!")
# or substitute a placeholder, or raise a new exception, etc.

Here is an example of loading a single value from simple JSON data, and converting back and forth to JSON:
import json
# load the data into an element
data={"test1": "1", "test2": "2", "test3": "3"}
# dumps the json object into an element
json_str = json.dumps(data)
# load the json to a string
resp = json.loads(json_str)
# print the resp
print(resp)
# extract an element in the response
print(resp['test1'])

Try this.
Here, I fetch only statecode from the COVID API (a JSON array).
import requests
r = requests.get('https://api.covid19india.org/data.json')
x = r.json()['statewise']
for i in x:
print(i['statecode'])

Try this:
from functools import reduce
import re
def deep_get_imps(data, key: str):
split_keys = re.split("[\\[\\]]", key)
out_data = data
for split_key in split_keys:
if split_key == "":
return out_data
elif isinstance(out_data, dict):
out_data = out_data.get(split_key)
elif isinstance(out_data, list):
try:
sub = int(split_key)
except ValueError:
return None
else:
length = len(out_data)
out_data = out_data[sub] if -length <= sub < length else None
else:
return None
return out_data
def deep_get(dictionary, keys):
return reduce(deep_get_imps, keys.split("."), dictionary)
Then you can use it like below:
res = {
"status": 200,
"info": {
"name": "Test",
"date": "2021-06-12"
},
"result": [{
"name": "test1",
"value": 2.5
}, {
"name": "test2",
"value": 1.9
},{
"name": "test1",
"value": 3.1
}]
}
>>> deep_get(res, "info")
{'name': 'Test', 'date': '2021-06-12'}
>>> deep_get(res, "info.date")
'2021-06-12'
>>> deep_get(res, "result")
[{'name': 'test1', 'value': 2.5}, {'name': 'test2', 'value': 1.9}, {'name': 'test1', 'value': 3.1}]
>>> deep_get(res, "result[2]")
{'name': 'test1', 'value': 3.1}
>>> deep_get(res, "result[-1]")
{'name': 'test1', 'value': 3.1}
>>> deep_get(res, "result[2].name")
'test1'

How do I get the value of a dict item within a list, within a dict?

How do I get the value of a dict item within a list, within a dict in Python? Please see the following code for an example of what I mean.
I use the following lines of code in Python to get data from an API.
res = requests.get('https://api.data.amsterdam.nl/bag/v1.1/nummeraanduiding/', params)
data = res.json()
data then returns the following Python dictionary:
{
'_links': {
'next': {
'href': null
},
'previous': {
"href": null
},
'self': {
'href': 'https://api.data.amsterdam.nl/bag/v1.1/nummeraanduiding/'
}
},
'count': 1,
'results': [
{
'_display': 'Maple Street 99',
'_links': {
'self': {
'href': 'https://api.data.amsterdam.nl/bag/v1.1/nummeraanduiding/XXXXXXXXXXXXXXXX/'
}
},
'dataset': 'bag',
'landelijk_id': 'XXXXXXXXXXXXXXXX',
'type_adres': 'Hoofdadres',
'vbo_status': 'Verblijfsobject in gebruik'
}
]
}
Using Python, how do I get the value for 'landelijk_id', represented by the twelve Xs?

This should work:
>>> data['results'][0]['landelijk_id']
"XXXXXXXXXXXXXXXX"
You can just chain those [] for each child you need to access.

I'd recommend using the jmespath package to make handling nested Dictionaries easier. https://pypi.org/project/jmespath/
import jmespath
import requests
res = requests.get('https://api.data.amsterdam.nl/bag/v1.1/nummeraanduiding/', params)
data = res.json()
print(jmespath.search('results[].landelijk_id', data)

Create partial dict from recursively nested field list

After parsing a URL parameter for partial responses, e.g. ?fields=name,id,another(name,id),date, I'm getting back an arbitrarily nested list of strings, representing the individual keys of a nested JSON object:
['name', 'id', ['another', ['name', 'id']], 'date']
The goal is to map that parsed 'graph' of keys onto an original, larger dict and just retrieve a partial copy of it, e.g.:
input_dict = {
"name": "foobar",
"id": "1",
"another": {
"name": "spam",
"id": "42",
"but_wait": "there is more!"
},
"even_more": {
"nesting": {
"why": "not?"
}
},
"date": 1584567297
}
should simplyfy to:
output_dict = {
"name": "foobar",
"id": "1",
"another": {
"name": "spam",
"id": "42"
},
"date": 1584567297,
}
Sofar, I've glanced over nested defaultdicts, addict and glom, but the mappings they take as inputs are not compatible with my list (might have missed something, of course), and I end up with garbage.
How can I do this programmatically, and accounting for any nesting that might occur?

you can use:
def rec(d, f):
result = {}
for i in f:
if isinstance(i, list):
result[i[0]] = rec(d[i[0]], i[1])
else:
result[i] = d[i]
return result
f = ['name', 'id', ['another', ['name', 'id']], 'date']
rec(input_dict, f)
output:
{'name': 'foobar',
'id': '1',
'another': {'name': 'spam', 'id': '42'},
'date': 1584567297}
here the assumption is that on a nested list the first element is a valid key from the upper level and the second element contains valid keys from a nested dict which is the value for the first element

Unable to append data to array

I am retrieving a record set from a database.
Then using a for statement I am trying to construct my data to match a 3rd party API.
But I get this error and can't figure it out:
"errorType": "TypeError", "errorMessage": "list indices must be
integers, not str"
"messages['english']['merge_vars']['vars'].append({"
Below is my code:
cursor = connect_to_database()
records = get_records(cursor)
template = dict()
messages = dict()
template['english'] = "SOME_TEMPLATE reminder-to-user-english"
messages['english'] = {
'subject': "Reminder (#*|code|*)",
'from_email': 'mail#mail.com',
'from_name': 'Notifier',
'to': [],
'merge_vars': [],
'track_opens': True,
'track_clicks': True,
'important': True
}
for record in records:
record = dict(record)
if record['lang'] == 'english':
messages['english']['to'].append({
'email': record['email'],
'type': 'to'
})
messages['english']['merge_vars'].append({
'rcpt': record['email']
})
for (key, value) in record.iteritems():
messages['english']['merge_vars']['vars'].append({
'name': key,
'content': value
})
else:
template['other'] = "SOME_TEMPLATE reminder-to-user-other"
close_database_connection()
return messages
The goal is to get something like this below:
messages = {
'subject': "...",
'from_email': "...",
'from_name': "...",
'to': [
{
'email': '...',
'type': 'to',
},
{
'email': '...',
'type': 'to',
}
],
'merge_vars': [
{
'rcpt': '...',
'vars': [
{
'content': '...',
'name': '...'
},
{
'content': '...',
'name': '...'
}
]
},
{
'rcpt': '...',
'vars': [
{
'content': '...',
'name': '...'
},
{
'content': '...',
'name': '...'
}
]
}
]
}

This code seems to indicate that messages['english']['merge_vars'] is a list, since you initialize it as such:
messages['english'] = {
...
'merge_vars': [],
...
}
And call append on it:
messages['english']['merge_vars'].append({
'rcpt': record['email']
})
However later, you treat it as a dictionary when you call:
messages['english']['merge_vars']['vars']
It seems what you want is something more like:
vars = [{'name': key, 'content': value} for key, value in record.iteritems()]
messages['english']['merge_vars'].append({
'rcpt': record['email'],
'vars': vars,
})
Then, the for loop is unnecessary.

What the error is saying is that you are trying to access an array element with the help of string not index (int).
I believe your mistake is in this line:
messages['english']['merge_vars']['vars'].append({..})
You declared merge_vars as array like so:
'merge_vars': []
So, you either make it dict like this:
'merge_vars': {}
Or, use it as array:
messages['english']['merge_vars'].append({..})
Hope it helps

Your issues, as the Error Message is saying, is here: messages['english']['merge_vars']['vars'].append({'name': key,'content': value})
The item messages['english']['merge_vars'] is a list and thus you're trying to access an element when you do something like list[i] and i cannot be a string, as is the case with 'vars'. You probably either need to drop the ['vars'] part or set messages['english']['merge_vars'] to be a dict so that it allows for additional indexing.