Did I try google?
Yes, I tried stack overflow, google, rubydocs, bunch of websites but there are minimal results to this and it's only ever mentioned indirectly. So yes, I did a lot of searching.
What's working?
I run the following query:
requests = Request.where("customer_id = ?
AND request_method != ?
AND request_time
BETWEEN ? AND ?",
customer.id, "OPTIONS", start_time, end_time).group('request_time')
As a result I get a bunch of values from the Database which look like this and this is CORRECT:
#<ActiveRecord::Relation[#<Request id: 171792, request_time: "2022-04-04 14:07:20">,
#<Request id: 171787, request_time: "2022-04-04 14:06:02">...]
NOTE: I didn't paste all the values because they have a similar structure.
What's the problem?
After running the query I want to pass it to the variable dates_init_hash = {} and merge it whilst counting into data[:requests]:
dates_init_hash = {}
(start_time.to_date..end_time.to_date).each do |date|
dates_init_hash[date] = 0
end
data[:requests] = dates_init_hash.merge(requests.count)
Unfortunately, I always seem to be getting the error:
ERROR -- : TypeError: no implicit conversion of Fixnum into Hash
Expected
I should be getting a Hash like the following:
{ "2022-03-24"=>2, "2022-03-25"=>1, "2022-03-28"=>3, "2022-03-29"=>11}
What I tried
I tried to convert the results to a hash before passing it over but this gave me the error that the .to_h method doesn't exist
data[:requests] = dates_init_hash.merge({requests: requests.count }) works half-way still causing errors
Questions
Why am I getting a Fixnum and why won't this work? How can I improve this? What would be the right way to solving this? I appreciate any kind of help.
Why is the error happening?
You are getting the error because when you run:
data[:requests] = dates_init_hash.merge(requests.count)
dates_init_hash is a hash, and requests.count is a number. So you are trying to merge a number into a hash, what is not allowed.
How can I fix it?
If what you want is to have the dates_init_hash with a mapping date => number of requests that date, you can do the following:
# initializes dates_init_hash with desired dates
dates_init_hash = {}
(start_time.to_date..end_time.to_date).each do |date|
dates_init_hash[date.iso8601] = 0
end
# iterates over reuests and add 1 to the date in dates_init_hash for each request in the desired date
requests.each do |request|
date = Date.parse(request[:request_time]).iso8601
next if dates_init_hash[date].nil?
dates_init_hash[date] += 1
end
Then, dates_init_hash will be something like
{"2022-04-04"=>1, "2022-04-05"=>0, "2022-04-06"=>1, "2022-04-07"=>0}
I'm new to erlang, and am running into an error with records in one of my modules. I'm emulating ships inside of a shipping_state, and I want to create a simple function that will print the ship id, name, and container cap of a certain ship, based on it's ID. I utilized list:keyfind, as I believe it will help, but perhaps I am not using it correctly. I have a .hrl file that contains the record declarations, and a .erl file with the function and initialization of my #shipping_state.
shipping.erl:
-module(shipping).
-compile(export_all).
-include_lib("./shipping.hrl").
get_ship(Shipping_State, Ship_ID) ->
{id, name, containercap} = list:keyfind(Ship_ID, 1, Shipping_State#shipping_state.ships).
shipping.hrl:
-record(ship, {id, name, container_cap}).
-record(container, {id, weight}).
-record(shipping_state,
{
ships = [],
containers = [],
ports = [],
ship_locations = [],
ship_inventory = maps:new(),
port_inventory = maps:new()
}
).
-record(port, {id, name, docks = [], container_cap}).
Result:
shipping:get_ship(shipping:init(),1).
** exception error: {badrecord,shipping_state}
in function shipping:get_ship/2 (shipping.erl, line 18)
I'd like to say that keyfind should work, and perhaps when I create the tuple {id, name, containercap}, something is wrong with the syntax there, but if I need to completely rethink how I would go about doing this problem, any assistance would be greatly appreciated.
Edit,
I've modified my code to follow Alexey's suggestions, however, there still appears to be the same error. Any further insights?
get_ship(Shipping_State, Ship_ID) ->
{ship, Id, Name, Containercap} = list:keyfind(Ship_ID, 2,
Shipping_State#shipping_state.ships),
io:format("id = ~w, name = ~s, container cap = ~w",[Id, Name, Containercap]).
See Internal Representation of Records: #ship{id=1,name="Santa Maria",container_cap=20} becomes {ship, 1, "Santa Maria", 20}, so the id is the 2nd element, not the first one.
{id, name, containercap} = ...
should be
#ship{id=Id, ...} = ...
or
{ship, Id, Name, Containercap} = ...
Your current code would only succeed if keyfind returned a tuple of 3 atoms.
The error {badrecord,shipping_state} is telling you that the code of get_ship expects its first argument to be a #shipping_state, but you pass {ok, #shipping_state{...}} (the result of init).
Records were added to the Erlang language because dealing with tuples fields by number was error-prone, especially as code changed during development and tuple fields were added, changed, or dropped. Don't use numbers to identify record fields, and don't treat records using their underlying tuple representation, as both work against the purpose of records and are unnecessary.
In your code, rather than using record field numbers with lists:keyfind/3, use the record names themselves. I've revised your get_ship/2 function to do this:
get_ship(Shipping_State, Ship_ID) ->
#ship{id=ID, name=Name, container_cap=ContainerCap} = lists:keyfind(Ship_ID, #ship.id, Shipping_State#shipping_state.ships),
io:format("id = ~w, name = ~s, container cap = ~w~n",[ID, Name, ContainerCap]).
The syntax #<record_name>.<record_field_name> provides the underlying record field number. In the lists:keyfind/3 call above, #ship.id provides the field number for the id field of the ship record. This will continue to work correctly even if you add fields to the record, and unlike a raw number it will cause a compilation error should you decide to drop that field from the record at some point.
If you load your record definitions into your shell using the rr command, you can see that #ship.id returns the expected field number:
1> rr("shipping.hrl").
[container,port,ship,shipping_state]
2> #ship.id.
2
With the additional repairs to your function above to handle the returned record correctly, it now works as expected, as this shell session shows:
3> {ok, ShippingState} = shipping:init().
{ok,{shipping_state,[{ship,1,"Santa Maria",20},
{ship,2,"Nina",20},
{ship,3,"Pinta",20},
{ship,4,"SS Minnow",20},
{ship,5,"Sir Leaks-A-Lot",20}],
[{container,1,200},
...
4> shipping:get_ship(ShippingState, 1).
id = 1, name = Santa Maria, container cap = 20
ok
Alexey's answer answers your question, in particular the 3rd point. I just want to suggest an improvement to your keyfind call. You need to pass the tuple index to it, but you can use record syntax to get that index without hard-coding it, like this:
list:keyfind(Ship_ID, #ship.id, Shipping_State#shipping_state.ships),
#ship.id returns the index of the id field, in this case 2. This makes it easier to read the code - no need to wonder what the constant 2 is for. Also, if for whatever reason you change the order of fields in the ship record, this code will still compile and do the right thing.
I'm trying to make templates for my dahboards, and I have problems when it comes to referring to measuerment names.
My variables:
$space = SHOW MEASUREMENTS
Then I would like a variable that contains only values from a specific $space, which is actually a MEASUREMENT:
$app = SHOW TAG VALUES WITH KEY = "Application" WHERE MEASUREMENT =~ /^$space$/
Here I get a message: Template variables could not be initialized: error parsing query: found MEASUREMENT, expected identifier, string, number, bool at line 1, char 48
In the official example it is like this, though it refers to another tag:
$datacenter = SHOW TAG VALUES WITH KEY = "datacenter"
$host = SHOW TAG VALUES WITH KEY = "hostname" WHERE "datacenter" =~ /^$datacenter$/
I cannot find any info how to refer to MEASUREMENTS which would work. WHERE, WITH, etc.. Maybe is it not possible at all?
I found only this in the official tutorial, but this is for keys, not values.
SHOW TAG KEYS [FROM <measurement_name>]
I actually figured it out:
SHOW TAG VALUES FROM /^$space$/ WITH KEY = "Application"
So, I'm doing like that at my controller action:
json_document = JSON(params) (json gem)
If I print json_document it gives me a Json like that:
{"createdAt":"Mar 6, 2012 6:12:54 PM","id":177139718620856322,"text":"#rgjunio where?","source":"web","isTruncated":false,"inReplyToStatusId":177139644012572673, ...
But when I try to access it:
tweet = Complaint.find_by_twitter_status json_document["inReplyToStatusId"]
i get the following error:
can't convert ActiveSupport::HashWithIndifferentAccess into String
So i tried another way using symbols:
tweet = Complaint.find_by_twitter_status json_document[:inReplyToStatusId]
but it gives me the error:
TypeError (can't convert Symbol into Integer)
Any idea?
Update:
If I use params[:inReplyToStatusId] isntead I got the following:
ActiveRecord::StatementInvalid (PG::Error: ERROR: operator does not exist: character varying = bigint
HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts.
SELECT "complaints".* FROM "complaints" WHERE "complaints"."twitter_status" = 177144980450721794 LIMIT 1):
Try:
params[:inReplyToStatusId].to_s
I have an array of hashes. Each entry looks like this:
- !map:Hashie::Mash
name: Connor H Peters
id: "506253404"
I'm trying to create a second array, which contains just the id values.
["506253404"]
This is how I'm doing it
second_array = first_array.map { |hash| hash[:id] }
But I'm getting this error
TypeError in PagesController#home
can't convert Symbol into Integer
If I try
second_array = first_array.map { |hash| hash["id"] }
I get
TypeError in PagesController#home
can't convert String into Integer
What am I doing wrong? Thanks for reading.
You're using Hashie, which isn't the same as Hash from ruby core. Looking at the Hashie github repo, it seems that you can access hash keys as methods:
first_array.map { |hash| hash.id }
Try this out and see if that works--make sure that it doesn't return the object_id. As such, you may want to double-check by doing first_array.map { |hash| hash.name } to see if you're really accessing the right data.
Then, provided it's correct, you can use a proc to get the id (but with a bit more brevity):
first_array.map(&:id)
This sounds like inside the map block that hash is not actually a hashie - it's an array for some reason.
The result is that the [] method is actually an array accessor method and requires an integer. Eg. hash[0] would be valid, but not hash["id"].
You could try:
first_array.flatten.map{|hash| hash.id}
which would ensure that if you do have any nested arrays that nesting is removed.
Or perhaps
first_array.map{|hash| hash.id if hash.respond_to?(:id)}
But either way you may end up with unexpected behaviour.