JSON

CSVs were and still are a very popular format for importing and 0:00 exporting data to and from databases and spreadsheets. 0:04 Much of the web though, runs on another common and 0:08 popular format, JSON, or JavaScript Object Notation. 0:10 No, I'm not trying to get you to write JavaScript, 0:14 Python's JSON module is very handy for encoding and decoding data from JSON. 0:18 You'll use this when you're receiving information in your API or 0:23 sending information to an API, or maybe you just want to use it to read and 0:26 write files on your server. 0:30 JSON is pretty common for 0:31 configuration files too, regardless of how you're going to use it, 0:32 it's a great format to know about, and a great library to know how to use. 0:36 Python's JSON library is pretty solid and I think, pretty easy to use. 0:41 Let's check out this JSON file about a piece of art 0:45 that I downloaded from the Minneapolis Institute of Art. 0:49 You can see that a lot of stuff in here, I can read it like it's a dictionary and 0:52 go, it's dated 1899, cool, but I don't wanna do that. 0:56 I wanna be able to do this in Python, right? 1:00 So I'm gonna make a new file and I'm gonna call this Art.pi, 1:03 and inside of here, first things first. 1:09 We need to import the JSON module, so 1:11 the JSON module has all of our handy dandy stuff in it. 1:14 So I'm going to open it up, what is this? 1:18 148.json as art file. 1:20 So I'm gonna open that up and I'm gonna say art = jason.load(artfile), 1:25 and then I'm gonna print(art['description']). 1:32 All right, cool? 1:38 So let's go run this. 1:40 And I get that it's a boat with two masts in front of a bridge with a lift-gate, 1:45 two row boats in water at left, buildings at left, trees at right, 1:49 that's the description I got from the JSON file. 1:52 Now that might not look like much but it's really handy if you're dealing with tons 1:55 of input from an outside source, or lots and lots and lots of files. 1:58 And you don't have to try and turn plain-text files in Python Objects or 2:02 anything like that through RegX or some sort of, I don't even know, 2:08 some sort of arcane incantation. 2:12 The load method, which we used right here, takes a file-like object and 2:15 tries to turn that into a Python object of some kind. 2:21 In this case, because what we have here is what we would call a dictionary in Python, 2:26 it just creates a dictionary, it creates an actual Python dictionary. 2:31 If we had a list, an array for JavaScript, then we would get a list 2:35 in Python, another way that we can do this is with the load s method. 2:41 You'll probably hear people call it loads instead of load s or 2:45 load string, I call it loads all the time. 2:48 Honestly, that's fine, that's what the word is, but the way that it's spelled, 2:52 what it is, is it's the way that we can take a string with embedded JSON in it and 2:56 turn that into a Python object. 3:01 Let's try that out, let's try it out down here in the shell. 3:04 We'll do Python, import json and 3:06 let's do nums = json.loads and 3:10 then a string of 1,2, and 3. 3:14 All right, and so now if I do nums[2] I get the number 3, 3:18 so we loaded the string in the JSON. 3:24 In that string there was an array of integers which the JSON module turned 3:27 into a list of ints and I think that's pretty handy. 3:31 The opposite of load and loads are the dump and 3:36 dumps methods, so let's try them out. 3:41 So we can do json.dumps([5, 4, 3, 2, 1]). 3:45 No quote marks, and now, I get a string which has the array of numbers in it, 3:52 so it's kinda like I turned the list into a string, 3:57 I mean, it almost seems like I get to str and then the list, right? 4:00 And I could on something this simple, but on something that's a little bit 4:05 more complicated, you obviously can't do that, let's try this. 4:08 I'm gonna make myself into a dictionary, so first_name is Kenenth, 4:11 last_name is Love, and my topic here at Treehouse Is Python. 4:17 All right, so I can't just do str(me), 4:24 I mean, I can but I don't get exactly the right thing, right? 4:28 So let's do json.dumps(me) and 4:33 while it looks the same, there is a difference because in JSON 4:37 you have to have double quotes instead of single quotes to make it valid. 4:40 So this is valid JSON, what I did before is not, and if I was to have 4:45 numbers like that in there, we'd want to change how those things worked. 4:49 We could also easily send this string out across the Internet with no problems, so 4:52 that's great, 4:57 that's super handy, we could do something similarly using the Dump method. 4:57 But Dump goes directly into a file-like object instead of into a string, 5:02 so we have me, let's make Craig. 5:08 So again, do first_name as Craig, 5:11 last_name as Dennis, and topic as Java all right? 5:16 So we have me, and we have Craig, and let's do with open 5:24 teachers.json, and a for append, although it doesn't really matter, 5:28 cuz we're writing into this for the first time, as teacherfile. 5:34 Then we wanna say json.dump, and 5:39 we're gonna dump an array of me and 5:43 craig into teacherfile, all right? 5:47 Let that run and now, let's shrink that down, refresh this, 5:52 if we checked out teachers.json that the file that we just created. 6:02 There's me, and I misspelled my own name, and 6:08 there's Craig, and it made a list of objects. 6:12 So that's pretty cool, that's super awesome, the JSON module is amazingly 6:17 handy for both encoding and decoding data to and from files and strings. 6:22 I find myself using it a lot with various APIs on the web, and 6:27 I bet that you will find it the same. 6:30