How to loop through JSON in Python - python

I can't figure out how to loop though a JSON object that is deeper than 1 level. The object is:
{
"data":[
{
"id":"251228454889939/insights/page_fan_adds_unique/day",
"name":"page_fan_adds_unique",
"period":"day",
"values":[
{
"value":9,
"end_time":"2012-05-29T07:00:00+0000"
},
{
"value":5,
"end_time":"2012-05-30T07:00:00+0000"
}
],
"title":"Daily New Likes",
"description":"Daily The number of new people who have liked your Page (Unique Users)"
},
{
"id":"251228454889939/insights/page_fan_adds/day",
"name":"page_fan_adds",
"period":"day",
"values":[
{
"value":9,
"end_time":"2012-05-29T07:00:00+0000"
},
{
"value":5,
"end_time":"2012-05-30T07:00:00+0000"
}
],
"title":"Daily New Likes",
"description":"Daily The number of new people who have liked your Page (Total Count)"
}
]
}
Code:
def parseJsonData(data):
output_json = json.loads(data)
for i in output_json:
print i
for k in output_json[i]:
print k
How come I can't access the object like: output_json[data][id]?
I get an error if I try this:
string indice must be an integer

Being that your "data" key is actually a list of objects, you cannot access the items by their "id" field directly. You would need to access each item by a list index such as:
output_json["data"][0]["id"]
Now, if what you want to do is to be able to index the members of "data" by the "id" field as the key, you could reformat your data:
# make "data" a dict {id: item, }, instead of list [item1, item2, ...]
output_json['data'] = dict((item['id'], item) for item in json_data['data'])
print output_json['data']
# {'251228454889939/insights/page_fan_adds_unique/day': ...
print output_json['data']['251228454889939/insights/page_fan_adds_unique/day']
# {'description': 'Daily The number of new p ...
# ways to loop over "data"
for id_, item in output_json['data'].iteritems():
print id_, item
for item in output_json['data'].itervalues():
print item
Otherwise what you have to do is just loop over "data", since there is no real correlation between the index and the object:
for item in output_json["data"]:
print item['id']
# 251228454889939/insights/page_fan_adds_unique/day
# 251228454889939/insights/page_fan_adds/day

What you pasted is not valid JSON. There is an unmatched [ after "data".
Based on this, I would guess that maybe the data isn't what you think it is. If the value of output_json[data] is a list, then you won't be able to access output_json[data][id]. Instead you'll have to do something like output_json[data][0][id], where the [0] accesses the first item in the list.

Related

How do I extract a list item from nested json in Python?

I have a json object and I'm trying to extract a couple of values from a nested list. Then print them in markup. I'm getting and error - AttributeError: 'list' object has no attribute 'get'
I understand that it's a list and I can't preform a get. I've been searching for the proper method for a few hours now and I'm running out of steam. I'm able to get the Event, but not Value1 and Value2.
This is the json object
{
"resource": {
"data": {
"event": "qwertyuiop",
"eventVersion": "1.05",
"parameters": {
"name": "sometext",
"othername": [
""
],
"thing": {
"something": {
"blah": "whatever"
},
"abc": "123",
"def": {
"xzy": "value"
}
},
"something": [
"else"
]
},
"whatineed": [{
"value1": "text.i.need",
"value2": "text.i.need.also"
}]
}
}
}
And this is my function
def parse_json(json_data: dict) -> Info:
some_data = json_data.get('resource', {})
specific_data = some_data.get('data', {})
whatineed_data = specific_data.get('whatineed', {})
formatted_json = json.dumps(json_data, indent=2)
description = f'''
h3. Details
*Event:* {some_data.get('event')}
*Value1:* {whatineed_data('value1')}
*Value2:* {whatineed_data('value2')}
'''
From the data structure, whatineed is a list with a single item, which in turn is a dictionary. So, one way to access it would be:
whatineed_list = specific_data.get('whatineed', [])
whatineed_dict = whatineed_list[0]
At this point you can do:
value1 = whatineed_dict.get('value1')
value2 = whatineed_dict.get('value2')
You can change your function to the following:
def parse_json(json_data: dict) -> Info:
some_data = json_data.get('resource')
specific_data = some_data.get('data', {})
whatineed_data = specific_data.get('whatineed', {})
formatted_json = json.dumps(json_data, indent=2)
description = '''
h3. Details
*Event:* {}
*Value1:* {}
*Value2:* {}
'''.format(some_data.get('data').get('event'),whatineed_data[0]['value1'], whatineed_data[0]['value2'])
Since whatineed_data is a list, you need to index the element first
Python handles json as strings unless they are coming directly from a file. This could be the source for some of your problems. Also this article might help.
Assuming that "whatineed" attribute is really a list, and it's elements are dicts, you can't call whatineed.get asking for Value1 or Value2 as if they are attributes, because it is a list and it don't have attributes.
So, you have two options:
If whatineed list has a single element ever, you can access this element directly and than access the element attributes:
element = whatineed[0]
v1 = element.get('value1', {})
v2 = element.get('value2', {})
Or, if whatineed list can have more items, so, you will need to iterate over this list and access those elements:
for element in whatineed:
v1 = element.get('value1', {})
v2 = element.get('value2', {})
## Do something with values

Update nested map dynamodb

I have a dynamodb table with an attribute containing a nested map and I would like to update a specific inventory item that is filtered via a filter expression that results in a single item from this map.
How to write an update expression to update the location to "in place three" of the item with name=opel,tags include "x1" (and possibly also f3)?
This should just update the first list elements location attribute.
{
"inventory": [
{
"location": "in place one", # I want to update this
"name": "opel",
"tags": [
"x1",
"f3"
]
},
{
"location": "in place two",
"name": "abc",
"tags": [
"a3",
"f5"
]
}],
"User" :"test"
}
Updated Answer - based on updated question statement
You can update attributes in a nested map using update expressions such that only a part of the item would get updated (ie. DynamoDB would apply the equivalent of a patch to your item) but, because DynamoDB is a document database, all operations (Put, Get, Update, Delete etc.) work on the item as a whole.
So, in your example, assuming User is the partition key and that there is no sort key (I didn't see any attribute that could be a sort key in that example), an Update request might look like this:
table.update_item(
Key={
'User': 'test'
},
UpdateExpression="SET #inv[0].#loc = :locVal",
ExpressionAttributeNames={
'#inv': 'inventory',
'#loc': 'location'
},
ExpressionAttributeValues={
':locVal': 'in place three',
},
)
That said, you do have to know what the item schema looks like and which attributes within the item should be updated exactly.
DynamoDB does NOT have a way to operate on sub-items. Meaning, there is no way to tell Dynamo to execute an operation such as "update item, set 'location' property of elements of the 'inventory' array that have a property of 'name' equal to 'opel'"
This is probably not the answer you were hoping for, but it is what's available today. You may be able to get closer to what you want by changing the schema a bit.
If you need to reference the sub-items by name, perhaps storing something like:
{
"inventory": {
"opel": {
"location": "in place one", # I want to update this
"tags": [ "x1", "f3" ]
},
"abc": {
"location": "in place two",
"tags": [ "a3", "f5" ]
}
},
"User" :"test"
}
Then your query would be:
table.update_item(
Key={
'User': 'test'
},
UpdateExpression="SET #inv.#brand.#loc = :locVal",
ExpressionAttributeNames={
'#inv': 'inventory',
'#loc': 'location',
'#brand': 'opel'
},
ExpressionAttributeValues={
':locVal': 'in place three',
},
)
But YMMV as even this has limitations because you are limited to identifying inventory items by name (ie. you still can't say "update inventory with tag 'x1'"
Ultimately you should carefully consider why you need Dynamo to perform these complex operations for you as opposed to you being specific about what you want to update.
You can update the nested map as follow:
First create and empty item attribute of type map. In the example graph is the empty item attribute.
dynamoTable = dynamodb.Table('abc')
dynamoTable.put_item(
Item={
'email': email_add,
'graph': {},
}
Update nested map as follow:
brand_name = 'opel'
DynamoTable = dynamodb.Table('abc')
dynamoTable.update_item(
Key={
'email': email_add,
},
UpdateExpression="set #Graph.#brand= :name, ",
ExpressionAttributeNames={
'#Graph': 'inventory',
'#brand': str(brand_name),
},
ExpressionAttributeValues = {
':name': {
"location": "in place two",
'tag': {
'graph_type':'a3',
'graph_title': 'f5'
}
}
Updating Mike's answer because that way doesn't work any more (at least for me).
It is working like this now (attention for UpdateExpression and ExpressionAttributeNames):
table.update_item(
Key={
'User': 'test'
},
UpdateExpression="SET inv.#brand.loc = :locVal",
ExpressionAttributeNames={
'#brand': 'opel'
},
ExpressionAttributeValues={
':locVal': 'in place three',
},
)
And whatever goes in Key={}, it is always partition key (and sort key, if any).
EDIT:
Seems like this way only works when with 2 level nested properties. In this case you would only use "ExpressionAttributeNames" for the "middle" property (in this example, that would be #brand: inv.#brand.loc). I'm not yet sure what is the real rule now.
DynamoDB UpdateExpression does not search on the database for matching cases like SQL (where you can update all items that match some condition). To update an item you first need to identify it and get primary key or composite key, if there are many items that match your criteria, you need to update one by one.
then the issue to update nested objects is to define UpdateExpression,ExpressionAttributeValues & ExpressionAttributeNames to pass to Dynamo Update Api .
I use a recursive function to update nested Objects on dynamoDB. You ask for Python but I use javascript, I think is easy to see this code and implents on Python:
https://gist.github.com/crsepulv/4b4a44ccbd165b0abc2b91f76117baa5
/**
* Recursive function to get UpdateExpression,ExpressionAttributeValues & ExpressionAttributeNames to update a nested object on dynamoDB
* All levels of the nested object must exist previously on dynamoDB, this only update the value, does not create the branch.
* Only works with objects of objects, not tested with Arrays.
* #param obj , the object to update.
* #param k , the seed is any value, takes sense on the last iteration.
*/
function getDynamoExpression(obj, k) {
const key = Object.keys(obj);
let UpdateExpression = 'SET ';
let ExpressionAttributeValues = {};
let ExpressionAttributeNames = {};
let response = {
UpdateExpression: ' ',
ExpressionAttributeNames: {},
ExpressionAttributeValues: {}
};
//https://stackoverflow.com/a/16608074/1210463
/**
* true when input is object, this means on all levels except the last one.
*/
if (((!!obj) && (obj.constructor === Object))) {
response = getDynamoExpression(obj[key[0]], key);
UpdateExpression = 'SET #' + key + '.' + response['UpdateExpression'].substring(4); //substring deletes 'SET ' for the mid level values.
ExpressionAttributeNames = {['#' + key]: key[0], ...response['ExpressionAttributeNames']};
ExpressionAttributeValues = response['ExpressionAttributeValues'];
} else {
UpdateExpression = 'SET = :' + k;
ExpressionAttributeValues = {
[':' + k]: obj
}
}
//removes trailing dot on the last level
if (UpdateExpression.indexOf(". ")) {
UpdateExpression = UpdateExpression.replace(". ", "");
}
return {UpdateExpression, ExpressionAttributeValues, ExpressionAttributeNames};
}
//you can try many levels.
const obj = {
level1: {
level2: {
level3: {
level4: 'value'
}
}
}
}
I had the same need.
Hope this code helps. You only need to invoke compose_update_expression_attr_name_values passing the dictionary containing the new values.
def compose_update_expression_attr_name_values(data: dict) -> (str, dict, dict):
""" Constructs UpdateExpression, ExpressionAttributeNames, and ExpressionAttributeValues for updating an entry of a DynamoDB table.
:param data: the dictionary of attribute_values to be updated
:return: a tuple (UpdateExpression: str, ExpressionAttributeNames: dict(str: str), ExpressionAttributeValues: dict(str: str))
"""
# prepare recursion input
expression_list = []
value_map = {}
name_map = {}
# navigate the dict and fill expressions and dictionaries
_rec_update_expression_attr_name_values(data, "", expression_list, name_map, value_map)
# compose update expression from single paths
expression = "SET " + ", ".join(expression_list)
return expression, name_map, value_map
def _rec_update_expression_attr_name_values(data: dict, path: str, expressions: list, attribute_names: dict,
attribute_values: dict):
""" Recursively navigates the input and inject contents into expressions, names, and attribute_values.
:param data: the data dictionary with updated data
:param path: the navigation path in the original data dictionary to this recursive call
:param expressions: the list of update expressions constructed so far
:param attribute_names: a map associating "expression attribute name identifiers" to their actual names in ``data``
:param attribute_values: a map associating "expression attribute value identifiers" to their actual values in ``data``
:return: None, since ``expressions``, ``attribute_names``, and ``attribute_values`` get updated during the recursion
"""
for k in data.keys():
# generate non-ambiguous identifiers
rdm = random.randrange(0, 1000)
attr_name = f"#k_{rdm}_{k}"
while attr_name in attribute_names.keys():
rdm = random.randrange(0, 1000)
attr_name = f"#k_{rdm}_{k}"
attribute_names[attr_name] = k
_path = f"{path}.{attr_name}"
# recursion
if isinstance(data[k], dict):
# recursive case
_rec_update_expression_attr_name_values(data[k], _path, expressions, attribute_names, attribute_values)
else:
# base case
attr_val = f":v_{rdm}_{k}"
attribute_values[attr_val] = data[k]
expression = f"{_path} = {attr_val}"
# remove the initial "."
expressions.append(expression[1:])

Accessing Nested Dict from JSON

I'm using requests and JSON to pull some data from an API, and I'm struggling with using a nested dict.
Here is the JSON data:
{"data": [
{
"ContactId": "123",
"EmailAddress": "abc#xyz.com",
"FirstName": null,
"LastName": null,
"ClickDate": "6/6/1966",
"Clicks": "5",
"IPAddress": "1.1.1.1.1",
"UserAgent": "IE8.0",
"UniqueLinksClicked": [
{
"LinkURL": "http://link1.com",
"LinkURL": "http://link2.com",
"LinkURL": "http://link3.com"
}
]
}
]}
I'm able to access all of the ContactID and other 1st level stuff fine, but I can't figure out how to traverse the "LinkURL" stuff.
Here is my python...
result = requests.get(requesturl, headers=headers)
jdata = json.loads(result.content)
for result in jdata["data"]:
contactID = str([(result["ContactId"])])
for result in jdata["data"]["UniqueLinksClicked"]: #I'm doing this wrong, but I'm not sure how.
print(ContactID + " " + str([(result["LinkURL"])]))
The line marked with a comment above generates a TypeError indicating it's a list, where I expected it to be a dict:
list indices must be integers or slices, not str
If instead I drop the ["data"] dereference and try to access "UniqueLinksClicked" on jdata:
for link in jdata["UniqueLinksClicked"]:
I get a key error because the ["UniqueLinksClicked"] is an item inside of the ["data"] dict.
How do I do this correctly?
You can iterate over the links in a nested loop. Do not use the same variable name result in two nested loops! Use a different variable name in the inner loop.
for link in result["UniqueLinksClicked"]:
print(ContactID, link["LinkURL"])
(Moved from question.)
[OP] was confused about the variable naming in the for variable1 in variable2["dict"]: portion. After some help from HÃ¥ken Lid, [they] figured it out.
It should look like this...
for item in jdata["data"]:
contactID = str([(item["ContactId"])])
print(contactID)
for link in item["UniqueLinksClicked"]:
print(link["LinkURL"])

Python JSON Element Access with 2 responses

I can't find the right search term to come up with an answer to this but I know it's a noob question. I'm accessing an API which returns either:
{
"Items":[
{
"Id":"12",
"Type":"Address",
"Highlight":"564754165545",
}
]
}
or sometimes:
{
"Items":[
{
"Id":"12",
"Type":"BuildingNumber",
"Highlight":"145454479854",
},
{
"Id":"12",
"Type":"Address",
"Highlight":"564754165545",
}
]
}
I need to get the "highlight" element data but only when type is address from a reply.
Thanks for your help and sorry I couldn't work out the name of the multiple rows to find this for myself.
Items is a list of dicts. According to your example, sometimes the list contains one item, and other times it contains two items.
for item in foo['Items']:
if item['Type'] == 'Address':
print (item['Highlight'])
Use following code
new_items = [ j for j in JSON['Items'] if j.get('Type') == 'Address' ]
JSON = {'Items' : new_items }
for only heighlight data
new_items = [ j.get('heighlight') for j in JSON['Items'] if j.get('Type') == 'Address' ]
To obtain a list of highlights objects with Address Type
[highlight for highlight in respose['Items'] if highlight['Type'] == 'Address']

Logic for building converter using python dictionary values

I have such slice of loaded json tp python dictionary (size_dict):
{
"sizeOptionName":"XS",
"sizeOptionId":"1528",
"sortOrderNumber":"7017"
},
{
"sizeOptionName":"S",
"sizeOptionId":"1529",
"sortOrderNumber":"7047"
},
{
"sizeOptionName":"M",
"sizeOptionId":"1530",
"sortOrderNumber":"7095"
}
and I have products with size Id (dictionary_prod):
{
"catalogItemId":"7627712",
"catalogItemTypeId":"3",
"regularPrice":"0.0",
"sizeDimension1Id":"1528",
"sizeDimension2Id":"0",
}
I need to make such as output for any product:
result_dict = {'variant':
[{"catalogItemId":"7627712", ...some other info...,
'sizeName': 'XS', 'sizeId': '1525'}}]}
so I need to convert size ID and add it to new result object
What is the best pythonic way to do this?
I dont know how to get right data from size_dict
if int(dictionary_prod['sizeDimension1Id']) > o:
(result_dict['variant']).append('sizeName': size_dict???)
As Tommy mentioned, this is best facilitated by mapping the size id's to their respective dictionaries.
size_dict = \
[
{
"sizeOptionName":"XS",
"sizeOptionId":"1528",
"sortOrderNumber":"7017"
},
{
"sizeOptionName":"S",
"sizeOptionId":"1529",
"sortOrderNumber":"7047"
},
{
"sizeOptionName":"M",
"sizeOptionId":"1530",
"sortOrderNumber":"7095"
}
]
size_id_map = {size["sizeOptionId"] : size for size in size_dict}
production_dict = \
[
{
"catalogItemId":"7627712",
"catalogItemTypeId":"3",
"regularPrice":"0.0",
"sizeDimension1Id":"1528",
"sizeDimension2Id":"0",
}
]
def make_variant(idict):
odict = idict.copy()
size_id = odict.pop("sizeDimension1Id")
odict.pop("sizeDimension2Id")
odict["sizeName"] = size_id_map[size_id]["sizeOptionName"]
odict["sizeId"] = size_id
return odict
result_dict = \
{
"variant" : [make_variant(product) for product in production_dict]
}
print(result_dict)
Your question is a little confusing but it looks like you have a list (size_dict) of dictionaries that contain some infroamtion and you want to do a lookup to find a particular element in the list that contains the SizeOptionName you are interested in so that you can read off the SizeOptionID.
So first you could organsie your size_dict as a dictionary rather than a list - i.e.
sizeDict = {"XS":{
"sizeOptionName":"XS",
"sizeOptionId":"1528",
"sortOrderNumber":"7017"
}, "S": {
"sizeOptionName":"S",
"sizeOptionId":"1529",
"sortOrderNumber":"7047"
}, ...
You could then read off the SizeOptionID you need by doing:
sizeDict[sizeNameYouAreLookingFor][SizeOptionID]
Alternative you could keep your current structure and just search the list of dictionaries that is size_dict.
So:
for elem in size_dict:
if elem.SizeOptionID == sizeYouAreLookingFor:
OptionID = elem.SizeOptionId
Or perhaps you are asking something else?

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