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making use of data in a JSON object
this example from a Well House Consultants training course
Source code: jload Module: R113
# making use of data in a JSON object
require 'json' # -------------- loading fh = File.new 'sample.json' content = fh.read info = JSON.parse content # "content" is a string of text # "info" is a Hash and / or List of Hashes and / or lists # --------------------------------------------------- # -------- Showing what has been loaded puts content[27] # gives the 28th character of the string puts info["timedat"] # gives a particular element of the hash # "timedat" happens to be a key in this data puts info["acc"][17]["which"] # drilling down into data # What keys do I have in "info" puts info.keys.join ", " # How many things have I under 'acc' which I happen to know is an Array puts info["acc"].count # Loop though those for k in 0...info["acc"].count puts info["acc"][k]["where"] end # --------------------------------------- # Aliasing part of the data structure for easier access # Shortform naming example - does same thing, but cuts out sections of name # ac is an alternative name for info["acc"] ac = info["acc"] for k in 0...ac.count puts ac[k]["where"] end # ---------------------------------------------------------- # --------- Let's change the data! # - Amend "when" field to absolute time for k in 0...ac.count ac[k]["when"] = info["timedat"] - ac[k]["when"] end # But this has only changed it in memory! # --------------------------------------------------------- # ------------ Saving changes in nes Json file # turn it back into a string newContent = JSON.dump info # And write to file outfile = File.new "absolute.json","w" outfile.write newContent outfile.close Learn about this subject
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