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JSON

4:32 with Jason Seifer

You may have heard of JSON before. No, I'm not talking about my name, I'm talking about the serialization format. JSON stands for JavaScript Object Notation and is a way of serializing data so you can access it later. Why are we talking about this in Ruby when it's JavaScript? I'm glad you asked! JSON is a plain text serialization format which means you don't really need any special software to read and write it -- you only need to be prepared for the different formats of objects inside it. JSON may have started with JavaScript but is in wide use now and it's pretty much standard that every programming language can read and write JSON.

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You may have heard of JSON before. 0:00

No, I'm not talking about my name. 0:02

I'm talking about the serialization format. 0:04

JSON stands for JavaScript Object Notation and 0:07

is a way of serializing data so that you can access it later. 0:11

Why are we talking about this in Ruby when it's JavaScript? 0:15

I'm so glad you asked. 0:19

JSON is a plain text serialization format, 0:21

which means you don't really need any special software to read or write it. 0:24

You only need to be prepared for the different formats of objects inside it. 0:29

JSON may have started with JavaScript, but it's in wide use now. 0:33

And it's pretty much standard that every programming language can read or 0:38

write JSON. 0:42

Let's take a look at reading, writing, and working with JSON now using Workspaces. 0:44

>> Okay, so let's go ahead and take a look at how we can use JSON in our Ruby code. 0:51

So first, here is the JSON documentation and 0:57

you can find that in notes right below the video. 1:01

Now, what we need to do is require it, and 1:03

then we can send in a string to the parse method. 1:06

And that should return an object for us. 1:10

So, let's go ahead and see how that works. 1:13

I'm gonna load up IRB. 1:15

And first, I need to require JSON. 1:17

I'm gonna create a string, here. 1:21

And we'll say that this string has a key 1:26

with the name Jason, and location of Treehouse, 1:31

and the year, which is 2015. 1:37

Okay, so we've got our case and json_string. 1:43

Now, if we wanted to turn that into a Ruby object, we could use that parse method. 1:45

So we could say JSON.parse, and then send in the string. 1:50

And we get back a Ruby object with everything correctly parsed. 1:56

It's got these hash keys for name, location, and year. 2:00

And we could assign this to a variable if we wanted to. 2:04

And this goes from string to a hash. 2:12

Similarly, if we had another hash. 2:18

Let's say my_hash is name Jason. 2:22

Now this is a Ruby hash, email jason@teamtreehouse.com. 2:29

And we'll say favorite numbers the array 2:35

with the numbers 1, 2, and 3. 2:41

So we've got this hash and if we want to turn that into 2:45

a JSON object, we can use JSON.dump(my_hash). 2:50

And now we get back a JSON string representation of our hash. 2:55

And this could be converted back as well. 3:01

So we could say, json_output = JSON.dump(my_hash). 3:03

Now we know that this is a string. 3:11

By asking it what class it is, okay, we know it's a string. 3:15

Now we could parse this just like other JSON, JSON.parse. 3:18

That output, would help if I spelled it correctly. 3:23

And we get back a Ruby hash based on that string. 3:28

And it even has an array as one of the members. 3:33

There's one other useful method with JSON, that we can use. 3:38

And that is the load method. 3:42

We can load JSON from a source, which could either be a string or a file. 3:45

So I've prepared an example JSON file here. 3:51

That just has that original JSON string in a file, and we can do JSON.load. 3:55

Now, remember we have to give this a file so we'll just say file.new. 4:01

And the path which is example.json. 4:04

And this returns our Ruby hash. 4:10

Now one thing to keep in mind when you are parsing JSON. 4:13

This is going directly into Ruby. 4:15

So, if you're going to use the load method, make sure that the data is trusted 4:19

and clean, or there could be security concerns. 4:24

Try working with JSON or your own now, using Workspaces. 4:28

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