#100DaysOfCode in Python Transcripts
Chapter: Days 97-99: Building JSON APIs
Lecture: Implementing the play-round method

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0:00 Alright, we are down to the big method,
0:03 this play_round.
0:04 It turns out this one is fairly complicated,
0:06 but its important right?
0:07 This is the way that you play a round in the game.
0:10 Okay I'm going to put some code here.
0:12 Its not going to be quite complete at first.
0:14 So, here we're going to get this thing called Game Round.
0:18 I've updated this Game Class, to have this game filed.
0:22 To have this Game Round,
0:23 and it basically stores all the information about who
0:26 rolled what, whether that roll is winning, or losing,
0:31 and who won that Round, and things like that.
0:33 It'll record it in the database,
0:35 and I'm not really going to go into it because it's
0:38 exactly the same logic as we had before but its just
0:40 kind of rewritten.
0:42 Okay, so we're going to use that here.
0:45 And we also have to do some validation.
0:46 Remember, up here, in our create_user.
0:50 We have ff not flask.json give the user and someone...
0:54 Turns out this is way more complicated.
0:56 So let me write one more method that will do this.
0:59 We'll just put that at the bottom here.
1:00 Look at all this validation.
1:01 Okay, so, we're going to come in and validate that we have a
1:04 JSON body.
1:05 That the game id was passed.
1:07 That the user was passed.
1:09 That if we try to get the user from the database the user exists
1:12 That a rule was passed.
1:13 That if we try to get the rule from the database by name,
1:15 the rule exists.
1:17 The game is not already over, etc...
1:19 We could just validate that and then re-ask those questions
1:22 above, but when you're doing web maps and you're doing
1:25 these data access things, if you already have a hold of
1:27 the roll and the user, just give them back.
1:30 What we're going to do is we're going to get those three pieces
1:32 as valid data or we'll have an exception and we'll just
1:35 return a response again, saying what went wrong.
1:39 And then we're going to jsonify the roll, the computer roll,
1:43 the player, the opponent, outcome, all the stuff we need to
1:45 basically keep track of the client and at least report to
1:48 the client what happened there.
1:50 Looks like that reload worked so let's go and see if we
1:54 can Play roll.
1:55 Lets verify that we have Michael.
1:58 Michael is there so Michael can play a game.
2:02 Lets go here and we can create another new game.
2:04 Turns out that it doesn't matter what we actually use there.
2:07 Let's look at the body.
2:09 We're going to pass in.
2:10 Some game id.
2:12 Doesn't have to exist it turns out.
2:14 Michael, and a Roll.
2:16 And let's see what we get.
2:19 Whoa, it worked, look at that.
2:20 We got a 200, response is JSON, very good.
2:24 So, what did we get down here.
2:27 Computer rolled water.
2:29 Is it the Final Round? No.
2:30 The opponent is the computer.
2:32 It's kind of not the best name, is it?
2:33 But the opponent is the computer,
2:35 the player is Michael.
2:36 We have our IDs.
2:37 Michael rolled rock.
2:39 Computer rolled water.
2:41 This is the First Round and the outcome is,
2:43 The Player loses.
2:44 Ugh, well, I'm not rolling rock anymore.
2:47 I'm going to roll human.
2:49 Let's try again. This time, they rolled scissors,
2:53 I rolled human, and I win.
2:55 Awesome. 2 for 2.
2:57 Let me just roll human a bunch of times.
2:59 And one of these times, its going to be the Final Round.
3:03 Final Round is True,
3:05 so if we go over here and ask for the status of this game,
3:08 now we can see if this thing actually works.
3:10 Oh, look, oh no, not quite the same.
3:12 Let's do that.
3:13 Boom, look at that, here's our status.
3:15 It's over, the moves are, you know,
3:18 Michael played rock, Computer played water,
3:20 Michael played human, Computer played scissors,
3:23 and then Michael just went human on it all the way the end.
3:27 Computer lost by trying to throw the sponge at us.
3:29 Okay.
3:30 Here's the players that were participating,
3:32 and the winner of this whole outcome is Michael.
3:35 How awesome is that?
3:37 And let's just do one more thing.
3:38 Let's do our error handling here.
3:40 Check our error handling.
3:42 What happens if we try to play a Round that's finished?
3:45 Remember there was an exception?
3:46 Boom, Invalid Request.
3:48 The game is already over, 400 bad requests.
3:51 Maybe it should be Invalid Operation? I don't know.
3:53 There's probably something better than bad requests.
3:54 But 404 is not it so we're going to go with 400 just for the
3:57 sake of time.
3:58 That probably felt like a lot, but the entire server is written
4:02 That's it, we're done.
4:03 We have play_round, top_scores, game_status, all_rolls,
4:07 now it's just a matter of literally going and writing
4:10 the client that's going to consume it.
4:12 And that turns out to be quite easy.