I am new to aws Lambda, I am struggling enough to find the solution dont know what to do. I have lambda handler function. my code is designed in such a way it works with the last value only. if I pass the data inside the console like:
Data=[['1700','340','2040']]
and pass it to lambda function. it works fine. But when I use API to pass the data as API request in configure test event and print the data , it change the json structure.
json data in test event:
{
"sum_net": 1700,
"sum_tax": 340,
"sum_gross": 2040
}
Handler function:
def handler(event,extract)
data= event.values()
return
result change the json object order. values are not the same as the manually defined dictionary. is there any way to keep the structure same.problem appears when json object changes to python dict. it changes the order of keys and values
Thank you in advance.
Extracted the answer from JSON order mixed up :
You may not rely on the ordering of elements within a JSON object.
From the JSON specification at http://www.json.org/
An object is an unordered set of
name/value pairs
As a consequence, lambda and any other JSON libraries are free to rearrange the order of the elements as they see fit.
The only way to change what lambda returns is to change lambda. If it is not an open-source AWS library and not open-source, it may not be easy at all.
If you know which is the value that you want from the handler, "sum_gross" I assume, you can directly get this value with the dictionary.get("key") method:
def handler(event,extract)
data = event.get("sum_gross");
return
more info about python dictionaries: http://www.tutorialspoint.com/python/dictionary_get.htm
Related
I am new to python and wanted to store the recentAveragePrice inside a variable (from a string like this one)
{"assetStock":null,"sales":250694,"numberRemaining":null,"recentAveragePrice":731,"originalPrice":null,"priceDataPoints":[{"value":661,"date":"2022-08-11T05:00:00Z"},{"value":592,"date":"2022-08-10T05:00:00Z"},{"value":443,"date":"2022-08-09T05:00:00Z"}],"volumeDataPoints":[{"value":155,"date":"2022-08-11T05:00:00Z"},{"value":4595,"date":"2022-08-10T05:00:00Z"},{"value":12675,"date":"2022-08-09T05:00:00Z"},{"value":22179,"date":"2022-08-08T05:00:00Z"},{"value":15181,"date":"2022-08-07T05:00:00Z"},{"value":14541,"date":"2022-08-06T05:00:00Z"},{"value":15310,"date":"2022-08-05T05:00:00Z"},{"value":14146,"date":"2022-08-04T05:00:00Z"},{"value":13083,"date":"2022-08-03T05:00:00Z"},{"value":14460,"date":"2022-08-02T05:00:00Z"},{"value":16809,"date":"2022-08-01T05:00:00Z"},{"value":17571,"date":"2022-07-31T05:00:00Z"},{"value":23907,"date":"2022-07-30T05:00:00Z"},{"value":39007,"date":"2022-07-29T05:00:00Z"},{"value":38823,"date":"2022-07-28T05:00:00Z"}]}
My current solution is this:
var = sampleStr[78] + sampleStr[79] + sampleStr[80]
It works for the current string but if the recentAveragePrice was above 999 it would stop working and i was wondering if instead of getting a fixed number i could search for it inside the string.
Your replit code shows that you're acquiring JSON data from some website. Here's an example based on the URL that you're using. It shows how you check the response status, acquire the JSON data as a Python dictionary then print a value associated with a particular key. If the key is missing, it will print None:
import requests
(r := requests.get('https://economy.roblox.com/v1/assets/10159617728/resale-data')).raise_for_status()
jdata = r.json()
print(jdata.get('recentAveragePrice'))
Output:
640
Since this is json you should just be able to parse it and access recentAveragePrice:
import json
sample_string = '''{"assetStock":null,"sales":250694,"numberRemaining":null,"recentAveragePrice":731,"originalPrice":null,"priceDataPoints":[{"value":661,"date":"2022-08-11T05:00:00Z"},{"value":592,"date":"2022-08-10T05:00:00Z"},{"value":443,"date":"2022-08-09T05:00:00Z"}],"volumeDataPoints":[{"value":155,"date":"2022-08-11T05:00:00Z"},{"value":4595,"date":"2022-08-10T05:00:00Z"},{"value":12675,"date":"2022-08-09T05:00:00Z"},{"value":22179,"date":"2022-08-08T05:00:00Z"},{"value":15181,"date":"2022-08-07T05:00:00Z"},{"value":14541,"date":"2022-08-06T05:00:00Z"},{"value":15310,"date":"2022-08-05T05:00:00Z"},{"value":14146,"date":"2022-08-04T05:00:00Z"},{"value":13083,"date":"2022-08-03T05:00:00Z"},{"value":14460,"date":"2022-08-02T05:00:00Z"},{"value":16809,"date":"2022-08-01T05:00:00Z"},{"value":17571,"date":"2022-07-31T05:00:00Z"},{"value":23907,"date":"2022-07-30T05:00:00Z"},{"value":39007,"date":"2022-07-29T05:00:00Z"},{"value":38823,"date":"2022-07-28T05:00:00Z"}]}'''
data = json.loads(sample_string)
recent_price = data['recentAveragePrice']
print(recent_price)
outputs:
731
Your data is in a popular format called JSON (JavaScript Object Notation). It's commonly used to exchange data between different systems like a server and a client, or a Python program and JavaScript program.
Now Python doesn't use JSON per-se, but it has a data type called a dictionary that behaves very similarly to JSON. You can access elements of a dictionary as simply as:
print(my_dictionary["recentAveragePrice"])
Python has a built-in library meant specifically to handle JSON data, and it includes a function called loads() that can convert a string into a Python dictionary. We'll use that.
Finally, putting all that together, here is a more robust program to help parse your string and pick out the data you need. Dictionaries can do a lot more cool stuff, so make sure you take a look at the links above.
# import the JSON library
# specifically, we import the `loads()` function, which will convert a JSON string into a Python object
from json import loads
# let's store your string in a variable
original_string = """
{"assetStock":null,"sales":250694,"numberRemaining":null,"recentAveragePrice":731,"originalPrice":null,"priceDataPoints":[{"value":661,"date":"2022-08-11T05:00:00Z"},{"value":592,"date":"2022-08-10T05:00:00Z"},{"value":443,"date":"2022-08-09T05:00:00Z"}],"volumeDataPoints":[{"value":155,"date":"2022-08-11T05:00:00Z"},{"value":4595,"date":"2022-08-10T05:00:00Z"},{"value":12675,"date":"2022-08-09T05:00:00Z"},{"value":22179,"date":"2022-08-08T05:00:00Z"},{"value":15181,"date":"2022-08-07T05:00:00Z"},{"value":14541,"date":"2022-08-06T05:00:00Z"},{"value":15310,"date":"2022-08-05T05:00:00Z"},{"value":14146,"date":"2022-08-04T05:00:00Z"},{"value":13083,"date":"2022-08-03T05:00:00Z"},{"value":14460,"date":"2022-08-02T05:00:00Z"},{"value":16809,"date":"2022-08-01T05:00:00Z"},{"value":17571,"date":"2022-07-31T05:00:00Z"},{"value":23907,"date":"2022-07-30T05:00:00Z"},{"value":39007,"date":"2022-07-29T05:00:00Z"},{"value":38823,"date":"2022-07-28T05:00:00Z"}]}
"""
# convert the string into a dictionary object
dictionary_object = loads(original_string)
# access the element you need
print(dictionary_object["recentAveragePrice"])
Output upon running this program:
$ python exp.py
731
When I run the code:
import requests
import json
def get_fact():
catFact = requests.get("https://catfact.ninja/fact?max_length=140")
json_data = json.loads(catFact.text)
return json_data
print(get_fact())
The output is like
{'fact': "Cats are the world's most popular pets, outnumbering dogs by as many as three to one", 'length': 84}
However I just want the fact.
How do I get rid of the 'fact:' at the front and 'length:' at the back?
What you want is to access the key in the python dict you made with the json.loads call. We actually don't need the json library as requests can read and deserialize JSON itself.
This code also checks if the response was OK and fails with informative error message. It follows PEP 20 – The Zen of Python.
import requests
def get_fact():
# Get the facts dictionary in a JSON serialized form.
cat_fact_response = requests.get("https://catfact.ninja/fact?max_length=140")
# Let the response raise the exception if something bad happened to the cat facts server connection.
cat_fact_response.raise_for_status()
# Deserialize the json (make a Python dict from the text we got). requests can do that on it's own:
cat_fact_dict = cat_fact_response.json()
# Access the fact from the json from the dictionary
return cat_fact_dict['fact']
print(get_fact())
When called you get following output as wanted:
# python3 script.py
The cat's tail is used to maintain balance.
Short answer:
you need to use either get_fact()['fact'] or get_fact().get('fact'). The former will throw an exception if fact doesn't exist whereas the latter will return None.
Why:
In your code sample you fetch some json data, and then print out the entire bit of json. When you parse json, the output is a key/value map called a dictionary (or map or object in other languages). The dictionary in this case contains two keys: fact and length. If you only one want of the values, then you need to tell python that you want only a single value -- fact in this case.
Remember though: this wouldn't apply to every json object you read. Not every one is going to have a fact key.
What you are returning in get_fact is a complete JSON object which you are then printing.
To get just its property fact (without the length) use a reference to that key or property like:
return json_data["fact"]
Below is also a link to a tutorial on using JSON in Python:
w3schools: Python JSON
To extract fact field from the response, use:
import requests
import json
def get_fact():
catFact = requests.get("https://catfact.ninja/fact?max_length=140")
json_data = json.loads(catFact.text)
return json_data['fact'] # <- HERE
print(get_fact())
Output:
Cats have "nine lives" thanks to a flexible spine and powerful leg and back muscles
Note: you don't need json module here, use json() method of Response instance returned by requests:
import requests
def get_fact():
catFact = requests.get("https://catfact.ninja/fact?max_length=140").json()
return catFact['fact']
print(get_fact())
A bit lost after much research. My code below parses the JSON to a dictionary I have thought using json load
response = json.load(MSW) # -->Will take a JSON String & Turn it into a python dict
Using the iteration below I return a series like this which is fine
{u'swell': {u'components': {u'primary': {u'direction': 222.5}}}}
{u'swell': {u'components': {u'primary': {u'direction': 221.94}}}}
ourResult = response
for rs in ourResult:
print rs
But how oh how do I access the 222.5 value. The above appears to just be one long string eg response[1] and not a dictionary structure at all.
In short all I need is the numerical value (which I assume is a part of that sting) so I can test conditions in the rest of my code. Is is a dictionary? With thanks as new and lost
You have to use python syntax as follows:
>>> print response['swell']['components']['primary']['direction']
222.5
Just access the nested dictionaries, unwrapping each layer with an additional key:
for rs in ourResult:
print rs['components']['primary']['direction']
I have a simple Firebase that I mostly interact with via Javascript, which works really well. However, I also have a Python program that needs to get data from existing children and put/update data on existing children. I tried python-firebasin, which would do what I want, but it is unreliable (hangs, fails, etc.).
So I'm looking at the python-firebase REST wrapper. This seems efficient, and works well. However, every time I try to post() data, I get not just the data I'm posting, but some kind of unique string paired with it, all inserted as a child.
For example, via Javascript, I might say:
db = new Firebase('https://myfirebase.firebaseio.com/testval/');
db.transaction(function(current) { return 1; });
This would then give me a Firebase that looked like:
|---testval: 1
But when I try to do something similar with the Python Firebase REST wrapper, such as:
db = firebase.FirebaseApplication('https://myfirebase.firebaseio.com/')
db.post('/testval/',1)
My Firebase looks something like this:
|---testval:
|---JI4BiBbICSEAnM9mDXf: 1
In other words, it inserts a new child, gives it a new string, and then appends the data. Is there any way to insert/modify data on my Firebase using the REST wrapper that would do it cleanly like I'm doing with Javascript? Without adding children, without adding these unique strings?
Try this instead:
db.put(1)
db.post() is the equivalent of .push() in the JavaScript API, so it creates a unique ID for you. db.put() is equivalent to .set() and will just set the data, which appears to be what you want.
Note that there is no equivalent for transactions in the REST API, but your example was just using a transaction to do a .set() so hopefully you don't actually need them.
Try this:
db = firebase.FirebaseApplication('https://myfirebase.firebaseio.com/')
db.put('', 'testval', 1)
put takes three arguments : first is url or path, second is the key name or the snapshot name and third is the data(json)
I'm trying to load JSON back into an object. The "loads" method seems to work without error, but the object doesn't seem to have the properties I expect.
How can I go about examining/inspecting the object that I have (this is web-based code).
results = {"Subscriber": {"firstname": "Neal", "lastname": "Walters"}}
subscriber = json.loads(results)
for item in inspect.getmembers(subscriber):
self.response.out.write("<BR>Item")
for subitem in item:
self.response.out.write("<BR> SubItem=" + subitem)
The attempt above returned this:
Item
SubItem=__class__
I don't think it matters, but for context:
The JSON is actually coming from a urlfetch in Google App Engine to
a rest web service created using this utility:
http://code.google.com/p/appengine-rest-server.
The data is being retrieved from a datastore with this definition:
class Subscriber(db.Model):
firstname = db.StringProperty()
lastname = db.StringProperty()
Thanks,
Neal
Update #1: Basically I'm trying to deserialize JSON back into an object.
In theory it was serialized from an object, and I want to now get it back into an object.
Maybe the better question is how to do that?
Update #2: I was trying to abstract a complex program down to a few lines of code, so I made a few mistakes in "pseudo-coding" it for purposes of posting here.
Here's a better code sample, now take out of website where I can run on PC.
results = '{"Subscriber": {"firstname": "Neal", "lastname": "Walters"}}'
subscriber = json.loads(results)
for key, value in subscriber.items():
print " %s: %s" %(key, value)
The above runs, what it displays doesn't look any more structured than the JSON string itself. It displays this:
Subscriber: {u'lastname': u'Walters', u'firstname': u'Neal'}
I have more of a Microsoft background, so when I hear serialize/deserialize, I think going from an object to a string, and from a string back to an object. So if I serialize to JSON, and then deserialize, what do I get, a dictionary, a list, or an object? Actually, I'm getting the JSON from a REST webmethod, that is on my behalf serializing my object for me.
Ideally I want a subscriber object that matches my Subscriber class above, and ideally, I don't want to write one-off custom code (i.e. code that would be specific to "Subscriber"), because I would like to do the same thing with dozens of other classes. If I have to write some custom code, I will need to do it generically so it will work with any class.
Update #3: This is to explain more of why I think this is a needed tool. I'm writing a huge app, probably on Google App Engine (GAE). We are leaning toward a REST architecture for several reasons, but one is that our web GUI should access the data store via a REST web layer. (I'm a lot more used to SOAP, so switching to REST is a small challenge in itself). So one of the classic ways of getting and update data is through a business or data tier. By using the REST utility mention above, I have the choice of XML or JSON. I'm hoping to do a small working prototype of both before we develop the huge app). Then, suppose we have a successful app, and GAE doubles it prices. Then we can rewrite just the data tier, and take our Python/Django user tier (web code), and run it on Amazon or somewhere else.
If I'm going to do all that, why would I want everything to be dictionary objects. Wouldn't I want the power of full-blown class structure? One of the next tricks is sort of an object relational mapping (ORM) so that we don't necessarily expose our exact data tables, but more of a logical layer.
We also want to expose a RESTful API to paying users, who might be using any language. For them, they can use XML or JSON, and they wouldn't use the serialize routine discussed here.
json only encodes strings, floats, integers, javascript objects (python dicts) and lists.
You have to create a function to turn the returned dictionary into a class and then pass it to a json.loads using the object_hook keyword argument along with the json string. Heres some code that fleshes it out:
import json
class Subscriber(object):
firstname = None
lastname = None
class Post(object):
author = None
title = None
def decode_from_dict(cls,vals):
obj = cls()
for key, val in vals.items():
setattr(obj, key, val)
return obj
SERIALIZABLE_CLASSES = {'Subscriber': Subscriber,
'Post': Post}
def decode_object(d):
for field in d:
if field in SERIALIZABLE_CLASSES:
cls = SERIALIZABLE_CLASSES[field]
return decode_from_dict(cls, d[field])
return d
results = '''[{"Subscriber": {"firstname": "Neal", "lastname": "Walters"}},
{"Post": {"author": {"Subscriber": {"firstname": "Neal",
"lastname": "Walters"}}},
"title": "Decoding JSON Objects"}]'''
result = json.loads(results, object_hook=decode_object)
print result
print result[1].author
This will handle any class that can be instantiated without arguments to the constructor and for which setattr will work.
Also, this uses json. I have no experience with simplejson so YMMV but I hear that they are identical.
Note that although the values for the two subscriber objects are identical, the resulting objects are not. This could be fixed by memoizing the decode_from_dict class.
results in your snippet is a dict, not a string, so the json.loads would raise an exception. If that is fixed, each subitem in the inner loop is then a tuple, so trying to add it to a string as you are doing would raise another exception. I guess you've simplified your code, but the two type errors should already show that you simplified it too much (and incorrectly). Why not use an (equally simplified) working snippet, and the actual string you want to json.loads instead of one that can't possibly reproduce your problem? That course of action would make it much easier to help you.
Beyyond peering at the actual string, and showing some obvious information such as type(subscriber), it's hard to offer much more help based on that clearly-broken code and such insufficient information:-(.
Edit: in "update2", the OP says
It displays this: Subscriber: {u'lastname': u'Walters', u'firstname': u'Neal'}
...and what else could it possibly display, pray?! You're printing the key as string, then the value as string -- the key is a string, and the value is another dict, so of course it's "stringified" (and all strings in JSON are Unicode -- just like in C# or Java, and you say you come from a MSFT background, so why does this surprise you at all?!). str(somedict), identically to repr(somedict), shows the repr of keys and values (with braces around it all and colons and commas as appropriate separators).
JSON, a completely language-independent serialization format though originally centered on Javascript, has absolutely no idea of what classes (if any) you expect to see instances of (of course it doesn't, and it's just absurd to think it possibly could: how could it possibly be language-independent if it hard-coded the very concept of "class", a concept which so many languages, including Javascript, don't even have?!) -- so it uses (in Python terms) strings, numbers, lists, and dicts (four very basic data types that any semi-decent modern language can be expected to have, at least in some library if not embedded in the language proper!). When you json.loads a string, you'll always get some nested combination of the four datatypes above (all strings will be unicode and all numbers will be floats, BTW;-).
If you have no idea (and don't want to encode by some arbitrary convention or other) what class's instances are being serialized, but absolutely must have class instances back (not just dicts etc) when you deserialize, JSON per se can't help you -- that metainformation cannot possibly be present in the JSON-serialized string itself.
If you're OK with the four fundamental types, and just want to see some printed results that you consider "prettier" than the default Python string printing of the fundamental types in question, you'll have to code your own recursive pretty-printing function depending on your subjective definition of "pretty" (I doubt you'd like Python's own pprint standard library module any more than you like your current results;-).
My guess is that loads is returning a dictionary. To iterate over its content, use something like:
for key, value in subscriber.items():
self.response.out.write("%s: %s" %(key, value))