I've got the following array
[#<Attachment id: 73, container_id: 1, container_type: "Project", filename: "Eumna.zip", disk_filename: "140307233750_Eumna.zip", filesize: 235303, content_type: nil, digest: "9a10843635b9e9ad4241c96b90f4d331", downloads: 0, author_id: 1, created_on: "2014-03-07 17:37:50", description: "", disk_directory: "2014/03">, #<Attachment id: 74, container_id: 1, container_type: "Project", filename: "MainApp.cs", disk_filename: "140307233750_MainApp.cs", filesize: 1160, content_type: nil, digest: "6b985033e19c5a88bb5ac4e87ba4c4c2", downloads: 0, author_id: 1, created_on: "2014-03-07 17:37:50", description: "", disk_directory: "2014/03">]
I need to extract the value 73 and 74 from this string which is Attachment id.
is there any way to extract this value
just in case author meant he has an actual String instance:
string = '[#<Attachment id: 73, container_id: 1, container_type: "Project", filename: "Eumna.zip", disk_filename: "140307233750_Eumna.zip", filesize: 235303, content_type: nil, digest: "9a10843635b9e9ad4241c96b90f4d331", downloads: 0, author_id: 1, created_on: "2014-03-07 17:37:50", description: "", disk_directory: "2014/03">, #<Attachment id: 74, container_id: 1, container_type: "Project", filename: "MainApp.cs", disk_filename: "140307233750_MainApp.cs", filesize: 1160, content_type: nil, digest: "6b985033e19c5a88bb5ac4e87ba4c4c2", downloads: 0, author_id: 1, created_on: "2014-03-07 17:37:50", description: "", disk_directory: "2014/03">]'
string.scan(/\sid: (\d+)/).flatten
=> ["73", "74"]
Do as below using Array#collect:
array.collect(&:id)
In case it is a string use JSON::parse to get the array back from the string first, then use Array#collect method as below :
require 'json'
array = JSON.parse(string)
array.collect(&:id)
The elements of the array (I'll call it a) look like instances of the class Attachment (not strings). You can confirm that by executing e.class in IRB, where e is any element a (e.g., a.first). My assumption is correct if it returns Attachment. The following assumes that is the case.
#Arup shows how to retrieve the values of the instance variable #id when it has an accessor (for reading):
a.map(&:id)
(aka collect). You can see if #id has an accessor by executing
e.instance_methods(false)
for any element e of a. This returns an array which contains all the instance methods defined for the class Attachment. (The argument false causes Ruby's built-in methods to be excluded.) If #id does not have an accessor, you will need to use Object#instance_variable_get:
a.map { |e| e.instance_variable_get(:#id) }
(You could alternatively write the argument as a string: "#id").
If
s = '[#<Attachment id: 73, container_id: 1,..]'
in fact a string, but you neglected to enclose it in (single) quotes, then you must execute
a = eval(s)
to convert it to an array of instances of Attachment before you can extract the values of :#a.
Hear that 'click'? That was me starting my stop watch. I want to see how long it will take for a comment to appear that scolds me for suggesting the use of (the much-maligned) eval.
Two suggestions: shorten code to the essentials and avoid the need for readers to scroll horizontally to read it. Here, for example, you could have written this:
a = [#<Attachment id: 73, container_id: 1>, #<Attachment id: 74, container_id: 1>]
All the instance variables I've removed are irrelevant to the question.
If that had been too long to fit on one lines (without scrolling horizontally, write it as:
a = [#<Attachment id: 73, container_id: 1>,
#<Attachment id: 74, container_id: 1>]
Lastly, being new to SO, have a look at this guide.
Related
In Elixir, we can IO.inspect anyStructure to get anyStructure's internals printed to output. Is there a similar method to output it to a file (or, as a more flexible solution, to a string)?
I've looked through some articles on debugging and io but don't see a solution. I've also tried
{:ok, file} = File.open("test.log", [:append, {:delayed_write, 100, 20}])
structure = %{ a: 1, b: 2 }
IO.binwrite(file, structure)
File.close file
but that results in
no function clause matching in IO.binwrite/2 [...]
def binwrite(device, iodata) when is_list(iodata) or is_binary(iodata)
I’ve also googled some "elixir serialize" and "elixir object to string", but haven't found anything useful (like :erlang.term_to_binary which returns, well, binary). Is there a simple way to get the same result that IO.inspect prints, into a file or a string?
There is already inspect/2 function (not the same as IO.inspect), just go with it:
#> inspect({1,2,3})
"{1, 2, 3}"
#> h inspect/2
def inspect(term, opts \\ [])
#spec inspect(
Inspect.t(),
keyword()
) :: String.t()
Inspects the given argument according to the Inspect protocol. The second
argument is a keyword list with options to control inspection.
You can do whatever you wish with the string afterwards.
You can give IO.inspect an additional param to tell it where to write to:
{:ok, pid} = StringIO.open("")
IO.inspect(pid, %{test: "data"}, label: "IO.inspect options work too \o/")
{:ok, {_in, out}} = StringIO.close(pid)
out # "IO.inspect options work too o/: %{test: \"data\"}\n"
It accepts a pid of a process to write to. StringIO provides such a process, returning you a string on close.
In Elixir, we can IO.inspect anyStructure to get anyStructure's internals printed to output.
This is not quite true; IO.inspect uses the Inspect protocol. What you see is not the internals of the struct, but whatever that struct's implementation of the Inspect protocol is written to produce. There are different options you can give to inspect, defined in Inspect.Opts, one of them is structs: false, which will print structs as maps.
For example, inspecting a range struct:
iex> inspect(1..10)
"1..10"
iex> inspect(1..10, structs: false)
"%{__struct__: Range, first: 1, last: 10, step: 1}"
To answer your question and to add to the other answers, here is a method that uses File.open!/3 to reuse an open file and log multiple inspect calls to the same file, then close the file:
File.open!("test.log", [:write], fn file ->
IO.inspect(file, %{ a: 1, b: 2 }, [])
IO.inspect(file, "logging a string", [])
IO.inspect(file, DateTime.utc_now!(), [])
IO.inspect(file, DateTime.utc_now!(), structs: false)
end)
This produces the following test.log file:
%{a: 1, b: 2}
"logging a string"
~U[2022-04-29 09:51:46.467338Z]
%{
__struct__: DateTime,
calendar: Calendar.ISO,
day: 29,
hour: 9,
microsecond: {485474, 6},
minute: 51,
month: 4,
second: 46,
std_offset: 0,
time_zone: "Etc/UTC",
utc_offset: 0,
year: 2022,
zone_abbr: "UTC"
}
You simply need to combine inspect/2 which returns a binary and File.write/3 or any other function dumping to a file.
File.write("test.log", inspect(%{a: 1, b: 2}, limit: :infinity))
Note the limit: :infinity option, without it the long structures will be truncated for better readability when inspecting to stdout.
I'm attempting to store some data into the session storage and I'm getting the same cookie error as this guy, the cookie is over the system byte limit of 4096.
This seems pretty straight forward, don't attempt to store more than the system limit in the session. Right, but I'm not attempting to do that. Clearly, the cookie is over 4096 bytes and my additions have caused it to overflow, but that doesn't explain where the data is.
The data I'm attempting to store is only 1500 bytes. In fact, the entire session that is being saved is 1500 bytes (the errored session). Thats nowhere near the overflow limit. So that means one thing for certain: The data stored in :plug_session inside of conn is not the only data being stored inside of the session cookie.
This is the session that's throwing the CookieOverflowError:
:plug_session => %{
"_csrf_token" => "XmE4kgdxk4D0NwwlfTL77Ic62t123123sdfh1s",
"page_trail" => [{"/", "Catalog"}, {'/', "Catalog"}],
"shopping_cart_changeset" => #Ecto.Changeset<
action: nil,
changes: %{
order: #Ecto.Changeset<
action: :insert,
changes: %{
address: #Ecto.Changeset<
action: :insert,
changes: %{
address_one: "800 Arola Drive, apt 321, apt 321",
address_two: "apt 321",
city: "Wooster",
company: "Thomas",
country: "US",
name: "user one",
phone: "3305551111",
state: "WV",
zip_code: "44691"
},
errors: [],
data: #FulfillmentCart.Addresses.Address<>,
valid?: true
>,
priority: false,
shipping_method: #Ecto.Changeset<
action: :insert,
changes: %{id: 2, is_priority?: false, name: "3 Day Select"},
errors: [],
data: #FulfillmentCart.ShippingMethods.ShippingMethod<>,
valid?: true
>
},
errors: [],
data: #FulfillmentCart.Orders.Order<>,
valid?: true
>
},
errors: [],
data: #FulfillmentCart.ShoppingCarts.ShoppingCart<>,
valid?: true
>,
"user_id" => 8
},
I actually followed this guide on decoding a phoenix session cookie, and I get the session before the error.
Which gives me:
iex(8)> [_, payload, _] = String.split(cookie, ".", parts: 3)
["SFMyNTY",
"g3QAAAADbQAAAAtfY3NyZl90b2tlbm0AAAAYWU92dkRfVDh5UXlRTUh4TGlpRTQxOFREbQAAAApwYWdlX3RyYWlsbAAAAAJoAm0AAAABL20AAAAHQ2F0YWxvZ2gCawABL20AAAAHQ2F0YWxvZ2ptAAAAB3VzZXJfaWRhCA",
"Ytg5oklzyWMvtu1vyXVvQ2xBzdtMnS9zVth7LIRALsU"]
iex(9)> {:ok, encoded_term } = Base.url_decode64(payload, padding: false)
{:ok,
<<131, 116, 0, 0, 0, 3, 109, 0, 0, 0, 11, 95, 99, 115, 114, 102, 95, 116, 111,
107, 101, 110, 109, 0, 0, 0, 24, 89, 79, 118, 118, 68, 95, 84, 56, 121, 81,
121, 81, 77, 72, 120, 76, 105, 105, 69, 52, 49, ...>>}
iex(10)> :erlang.binary_to_term(encoded_term)
%{
"_csrf_token" => "YOvvD_T8yQyQMHxLiiE418TD",
"page_trail" => [{"/", "Catalog"}, {'/', "Catalog"}],
"user_id" => 8
}
iex(11)>
This is 127 bytes, so the addition of the 1500 bytes isn't the problem. It's the other allocation of storage that isn't represented inside of the session. What is that?
My assumption of the byte size of the text itself in :plug_session is correct, but the reason the cookie is overflowing is not because the byte size of the decoded text in :plug_session is too big but that the encoded version of the :plug_session is too big. I figured this out by creating multiple cookies and looking at the byte_size of the data.
Save a new cookie
conn = put_resp_cookie(conn, "address",
changeset.changes.order.changes.address.changes, sign: true)
Get a saved cookie
def get_resp_cookie(conn, attribute) do
cookie = conn.req_cookies[attribute]
case cookie != nil do
false ->
{:invalid, %{}}
true ->
[_, payload, _] = String.split(cookie, ".", parts: 3)
{:ok, encoded_term } = Base.url_decode64(payload, padding: false)
{val, max, max_age} = :erlang.binary_to_term(encoded_term)
{:valid, val}
end
end
get_resp_cookie/2 pattern matching
address_map = case Connection.get_resp_cookie(conn, "address") do
{:invalid, val} -> IO.puts("Unable to find cookie.");val
{:valid, val} -> val
end
I made a few changes to the way I save the data from when I posted this. Namely I am now storing a map of changes, not the actual changeset...which means that the session most likely would've worked for me all along.
I think the answer to this issue was that the encoded %Ecto.Changeset{} was too big for the cookie to hold.
If you use this solution then be wary, you have to manage the newly created cookies yourself.
I have some records in a database tracking the price development on some items. These records often contains duplicates and repetitive sequences of price changes. I need to clean those up. Consider the following:
Record = Struct.new(:id, :created_at, :price)
records = [
Record.new(1, Date.parse('2017-01-01'), 150_000),
Record.new(2, Date.parse('2017-01-02'), 150_000),
Record.new(3, Date.parse('2017-01-03'), 130_000),
Record.new(4, Date.parse('2017-01-04'), 140_000),
Record.new(5, Date.parse('2017-01-05'), 140_000),
Record.new(6, Date.parse('2017-01-06'), 137_000),
Record.new(7, Date.parse('2017-01-07'), 140_000),
Record.new(8, Date.parse('2017-01-08'), 140_000),
Record.new(9, Date.parse('2017-01-09'), 137_000),
Record.new(10, Date.parse('2017-01-10'), 140_000),
Record.new(11, Date.parse('2017-01-11'), 137_000),
Record.new(12, Date.parse('2017-01-12'), 140_000),
Record.new(13, Date.parse('2017-01-13'), 132_000),
Record.new(14, Date.parse('2017-01-14'), 130_000),
Record.new(14, Date.parse('2017-01-15'), 132_000)
]
The policy should in plain words should be:
Remove any duplicates of exactly the same price immediately following each other.
Remove any records of a sequence of records with the same two prices jumping up and down for 2 times or more (e.g. [120, 110, 120, 110] but not [120, 110, 120]), so that only the initial price change is preserved.
In the above example the output that I would expect should be:
[
Record#<id: 1, created_at: Date#<'2017-01-01'>, price: 150_000>,
Record#<id: 3, created_at: Date#<'2017-01-03'>, price: 130_000>,
Record#<id: 4, created_at: Date#<'2017-01-04'>, price: 140_000>,
Record#<id: 6, created_at: Date#<'2017-01-06'>, price: 137_000>,
Record#<id: 13, created_at: Date#<'2017-01-13'>, price: 132_000>,
Record#<id: 14, created_at: Date#<'2017-01-14'>, price: 130_000>,
Record#<id: 14, created_at: Date#<'2017-01-14'>, price: 132_000>
]
Note: This is the most complicated example I can think of for the time being, if I find more, I'll update the question.
I have no problem dear sir of helping you with your challenge, here you go:
records_to_delete = []
# Cleanup duplicates
records.each_with_index do |record, i|
if i != 0 && record.price == records[i - 1].price
records_to_delete << record.id
end
end
records = records.delete_if{|record| records_to_delete.include?(record.id)}
# Remove repetitions
records_to_delete = []
records.each_with_index do |record, i|
if record.price == records[i + 2]&.price && records[i + 1]&.price == records[i + 3]&.price
records_to_delete << records[i+2].id
records_to_delete << records[i+3].id
end
end
records = records.delete_if{|record| records_to_delete.uniq.include?(record.id)}
I am trying to filter ActiveRecord_AssociationRelations to be unique by parent id.
So, I'd like a list like this:
[#<Message id: 25, posted_by_id: 3, posted_at: "2014-10-30 06:02:47", parent_id: 20, content: "This is a comment", created_at: "2014-10-30 06:02:47", updated_at: "2014-10-30 06:02:47">,
#<Message id: 23, posted_by_id: 3, posted_at: "2014-10-28 16:11:02", parent_id: 20, content: "This is another comment", created_at: "2014-10-28 16:11:02", updated_at: "2014-10-28 16:11:02">]}
to return this:
[#<Message id: 25, posted_by_id: 3, posted_at: "2014-10-30 06:02:47", parent_id: 20, content: "This is a comment", created_at: "2014-10-30 06:02:47", updated_at: "2014-10-30 06:02:47">]
I've tried various techniques including:
#messages.uniq(&:parent_id) # returns the same list (with duplicate parent_ids)
#messages.select(:parent_id).distinct # returns [#<Message id: nil, parent_id: 20>]
and uniq_by has been removed from Rails 4.1.
Have you tried
group(:parent_id)
It sounds to me like that is what you are after. This does return the first entry with the given parent_id. If you want the last entry you will have to reorder the result in a subquery and then use the group.
For me in Rails 3.2 & Postgresql, Foo.group(:bar) works on simple queries but gives me an error if I have any where clauses on there, for instance
irb> Message.where(receiver_id: 434).group(:sender_id)
=> PG::GroupingError: ERROR: column "messages.id" must appear in the
GROUP BY clause or be used in an aggregate function
I ended up specifying an SQL 'DISTINCT ON' clause to select. In a Message class I have the following scope:
scope :latest_from_each_sender, -> { order("sender_id ASC, created_at DESC").select('DISTINCT ON ("sender_id") *') }
Usage:
irb> Message.where(receiver_id: 434).latest_from_each_sender
I have a Hash #estate:
[#<Estate id: 1, Name: "Thane ", Address: "Thane St.", created_at: "2013-06-21 16:40:50", updated_at: "2013-06-21 16:40:50", user_id: 2, asset_file_name: "DSC02358.JPG", asset_content_type: "image/jpeg", asset_file_size: 5520613, asset_updated_at: "2013-06-21 16:40:49", Mgmt: "abc">,
#<Estate id: 2, Name: "Mumbai", Address: "Mumbai St.", created_at: "2013-06-21 19:13:59", updated_at: "2013-06-21 19:14:28", user_id: 2, asset_file_name: "DSC02359.JPG", asset_content_type: "image/jpeg", asset_file_size: 5085580, asset_updated_at: "2013-06-21 19:13:57", Mgmt: "abc">]
Is it possible to make new Hash with unique values according to the user_id: 2, because currently 2 elements have the user_id same i.e 2, I just want it once in the hash, what should I do ?
It seems to be something like a has_many relation between User model and Estate model, right? If I understood you correctly, than you need in fact to group your Estate by user_id:
PostgreSQL:
Estate.select('DISTINCT ON (user_id) *').all
MySQL:
Estate.group(:user_id).all
P.S. I'd not recommend to select all records from a database and then process them with Ruby as databases handle operations with data in much more efficient way.
Here is an sample example to get you a good start:
h = [ { a: 2, b: 3}, { a: 2, c: 3 } ]
h.uniq { |i| i[:a] }
# => [{:a=>2, :b=>3}]