I am trying to work with JSON data in Rails.
We need to save some countries in our JSON file which we support. We have created a form which a user can create a new country/state/pincode pair and this form will append the pair in the JSON file. After that, we need to read that JSON file and print which countries are supported.
We know how to read data from the JSON file, but we are having some issues while writing the data in the proper format.
This is the code for reading the data:
#data=JSON.parse( IO.read("public/dealer.json") )
How can I write data to a file from the form in JSON format?
Given a ruby object, you can generate a file with text in json format like so:
require 'json'
data = { "foo" => "bar" }
File.open("output.json", "w+") do |f|
f.write(JSON.generate(data))
end
require 'json'
data = [{ "foo" => "bar" } , { "foo1" => "bar1" }]
File.open("output.json", "w+") do |f|
f.write(JSON.generate(data))
end
Try this...!
Related
I'm trying to make a request to the PDFTables API, and save what is returned (an xml doc) in a new file. I have this code:
result = RestClient.post "https://pdftables.com/api?key=nn123450hsn", :myfile => File.new("./lib/assets/PeterValleyHexacoResults.pdf", "rb")
File.open('./lib/assets/test.xml', "w") do |f|
f.puts result
end`
When I view the newly saved file, it looks like a bunch of random symbols and characters in the editor. I'm not entirely sure what I'm doing wrong. Any help is appreciated.
You are getting the result in XLSX format. You need to specify XML in your request:
result = RestClient.post "https://pdftables.com/api?key=nn123450hsn&format=xml", :myfile => File.new("./lib/assets/PeterValleyHexacoResults.pdf", "rb")
I'm giving user opportunity to upload their files. However, application is not saving those files into the database, it only needs to get informations out of it.
So from a form which looks like this:
= simple_form_for #channel, method: :post do |f|
= f.input :name
= f.input :configuration_file, as: :file
= f.submit
come params[:channel][:configuration_file]
#<ActionDispatch::Http::UploadedFile:0xc2af27c #original_filename="485.csv", #content_type="text/csv", #headers="Content-Disposition: form-data; name=\"channel[configuration_file]\"; filename=\"485.csv\"\r\nContent-Type: text/csv\r\n", #tempfile=#<File:/tmp/RackMultipart20140822-6972-19sqxq2>>
How exactly can i read from this thing? I tried simply
File.open(params[:channel][:configuration_file])
but it returns error
!! #<TypeError: can't convert ActionDispatch::Http::UploadedFile into String>
PS
Additional solutions for xml and csv would be much appreciated!
According to the Rails docs:
http://api.rubyonrails.org/classes/ActionDispatch/Http/UploadedFile.html
an uploaded file supports the following instance methods, among others:
open()
path()
read(length=nil, buffer=nil)
you could try:
my_data = params[:channel][:configuration_file].read
to get a string of the file contents?
or even:
my_data = File.read params[:channel][:configuration_file].path
Also, if the file can be long, you may want to open the file and read line by line. A few solutions here:
How to read lines of a file in Ruby
If you want to read a CSV file, you could try:
require 'csv'
CSV.foreach(params[:channel][:configuration_file].path, :headers => true) do |row|
row_hash = row.to_hash
# Do something with the CSV data
end
Assuming you have headers in your CSV of course.
For XML I recommend the excellent Nokogiri gem:
http://nokogiri.org/
At least partly because it uses an efficient C library for navigating the XML. (This can be a problem if you're using JRuby). Its use is probably out of scope of this answer and adequately explained in the Nokogiri docs.
From the documentation
The actual file is accessible via the tempfile accessor, though some
of its interface is available directly for convenience.
You can change your code to:
file_content = params[:channel][:configuration_file].read
or if you want to use the File API:
file_content = File.read params[:channel][:configuration_file].path
So this is probably a simple question, but I've never done it before.
I have a Rails action that queries a database and creates a csv string from the query result.
I'd like to take the query string, put it into a .csv file, and when the user makes the http request associated with this method, the .csv file will download onto the user's machine.
How can I do this?
UPDATE
The file is sending from rails, but my angular app on the front end (that requested the csv) is not downloading it.
Here is the angular code I'm using to request the file from the rails app
$scope.csvSubmit = function() {
var csv = $.post('http://ip_addr:3000/api/csv', { 'input': $scope.query_box });
csv.done(function(result){
//empty - after the request is sent I want the csv file to download
})
}
You can use the send_file method, passing the path to the file as the first argument, as see in Rails documentation.
UPDATE
You can use a temporary file to save the CSV, like this:
require 'tempfile'
# automatically creates a file in /tmp
file = Tempfile.new('data.csv', 'w')
file.write('my csv')
file.close
send_file(file.path)
# remove the file from /tmp
file.unlink
UPDATE 2: AngularJS download
There are two ways to accomplish this: you can add a hidden href to download the file in the page and click it, or redirect the user to the Rails URL that sends the file when he clicks in the button. Note that the redirect will use parameters in the url, so it won't work well depending on the structure of query_box.
To add a hidden href to the page with the CSV:
$scope.csvSubmit = function() {
var csv = $.post('http://ip_addr:3000/api/csv', { 'input': $scope.query_box });
csv.done(function(result){
var hiddenElement = document.createElement('a');
hiddenElement.href = 'data:attachment/csv,' + encodeURI(result);
hiddenElement.target = '_blank';
hiddenElement.download = 'filename.csv';
hiddenElement.click();
})
}
To use the redirect:
$scope.csvSubmit = function() {
var url = 'http://ip_addr:3000/api/csv/?' + 'input=' + encodeURI($scope.query_box);
window.location = url;
}
I've had to do this plenty of times before. You need to set the response headers to get the browser to force the download.
I like to use the comma gem for rendering csv. Using the gem all you need to do is add the following lines to your controller action.
respond_to do |format|
format.csv do
response.headers['Content-Type'] = 'text/csv'
response.headers['Content-Disposition'] = 'attachment; filename=books.csv'
render :csv => Book.limited(50)
end
end
Then you just use the csv format and it works.
If you don't want to use comma. Just change the render line to render your csv string:
render :plain => csv_string_variable
Use send_data to generate a downloadable file from a string in just one line:
send_data #your_data, type: 'text/csv', disposition: 'attachment', filename: 'books.csv'
This is basically what I want to do, with the params given in a form, I want to do a GET/POST request to a site, this site expects an specific URL like http://site.com/user=XXX&size=XXX and it will give me back a JSON, I want to parse/save the data from this JSON into my rails app when the form is submitted.
I am totally lost with this manner, anything would be very appreciated.
Rails Form Data => Build the URL => Do a GET/Post request => Catch JSON => Parse => Save
for rest api you can use activeresource in your application
http://api.rubyonrails.org/classes/ActiveResource/Base.html
if it's something very specific you can use Net::Http to make requests and then parse json to ruby objects by yourself.
Examples of using http://www.rubyinside.com/nethttp-cheat-sheet-2940.html
for decoding json you can use
Json or ActiveSupport::JSON.decode or this https://github.com/flori/json
I guess you want to do a request to another not your site to get the response. So you can install curb gem (the curl wrapper in ruby). Then use it to make the request on another site and parse json with standart RoR tools like Json to hash.
From http://www.rubyinside.com/nethttp-cheat-sheet-2940.html you get you can do the following:
at the top of your file add:
require "net/http"
require "uri"
require 'json'
then in your controller or helper:
#set the uri
uri = URI.parse("http://my.site.com/uri")
#set the post params and get the respons
response = Net::HTTP.post_form(uri, {"first_param" => "my param", "second_param" => "another param"})
#get the json info
data = JSON.parse(response.body)
#set result to an ActiveRecord (maybe there is a better way to do this, I guess it depends on the response you get
#something = Mymodel.new
#something.name = data["name"]
...
#something.save
Hope it helps!
How do I parse a document in a table and send it across as a JSON file to another db.
Detailed Desc:
I have crawled and taken data into a table from websites using anemone. I need to now parse it and transfer it as a JSON file to another server. I think, I will have to first convert the document in the table into nokogiri document which can be parsed and converted to json file. Any idea how can I convert the doc into nokogiri document or if anyone has any other idea to parse it and send it as a json file ?
Nokogiri is your best bet for the HTML parsing, but as for converting it to JSON you're on your own from what I can tell.
Once you have it parsed via Nokogiri it shouldn't be terribly hard to extract the elements you need and generate JSON that represents them. What you're doing isn't a very common task, so you'll have to bridge the gap between Nokogiri and whichever gem you're using to generate the JSON.
Okay I found the answer long time back, I basically made use of REST to send message form one application to another, i sent it across as a hash. And the obvious one, I used nokogiri for parsing the table.
def post_me
#page_hash = page_to_hash
res = Net::HTTP.post_form(URI.parse('http://127.0.0.1:3007/element_data/save.json'),#page_hash)
end
For sending the hash from one application to another using net/http.
def page_to_hash
require 'rubygems'
require 'nokogiri'
require 'open-uri'
require 'domainatrix'
#page = self.page.sub(/^<!DOCTYPE html(.*)$/, '<!DOCTYPE html>')
hash={}
doc = Nokogiri::HTML(self.page)
doc.search('*').each do |n|
puts n.name
end
Using Nokogiri for parsing the page table in my model. page table had the whole body of a webpage.
file_type = []
file_type_data=doc.xpath('//a/#href[contains(. , ".pdf") or contains(. , ".doc")
or contains(. , ".xls") or contains(. , ".cvs") or contains(. , ".txt")]')
file_type_data.each do |href|
if href[1] == "/"
href = "http://" + website_url + href
end
file_type << href
end
file_type_str = file_type.join(",")
hash ={:head => head,:title => title, :body => self.body,
:image => images_str, :file_type => file_type_str, :paragraph => para_str, :description => descr_str,:keyword => key_str,
:page_url=> self.url, :website_id=>self.parent_request_id, :website_url => website_url,
:depth => self.depth, :int_links => #int_links_arr, :ext_links => #ext_links_arr
}
A simple parsing example and how i formed my hash.