WIP - Pulling a JSON object from a given Starred repo URL by Mordax · Pull Request #42 · 0xazure/supernova

Mordax · 2018-12-19T02:13:04Z

This PR is a work in progress - I'd love to get some feedback on it. Didn't expect Rust's syntax and style to trip me up so much as well as the compiler pointing out all the stuff that doesn't work. Will eventually close #37 .

Next steps -

Figuring out how to cleanly populate the Languages struct with the JSON object found at languages_url in the Repository struct in a way that doesn't make rustc hate me
Formatting the JSON object (which is just a non defined key-value pair) into a hash structure that makes logical sense
Sorting via most popular language, transforming the bytes data the GH API returns into something logical like pages
Displaying the information properly

…value

0xazure

Hey @Mordax, I've left some comments for you.

I think what's tripping you up the most is you're trying to follow the existing code as a model too closely; the work you're implementing interacts with the existing code, but there's very little similarity between it and what the new functionality should look like.

A thought for you as well, since you were interested in the CLI design for supernova: the current implementation will always grab the language data, what about adding a flag so the user can control if they are interested in language data or not?

0xazure · 2018-12-19T02:55:46Z

src/lib.rs

 struct Star {
    starred_at: DateTime<Utc>,
    repo: Repository,
+    //lang: Languages,


If we need this field on struct Star, but we don't want serde to look at the JSON response for a key of "lang"; we can tell serde to ignore a field using the skip directive so it won't be seen during (de)serialization.

I think this field should actually go on the Repository type since it's data about the repository and not the star itself.

Note that repositories may also have a(n optionally null) "language" key, which denotes the primary language for the repository.

0xazure · 2018-12-19T02:56:47Z

src/lib.rs

    full_name: String,
    description: Option<String>,
    stargazers_count: i32,
+    languages_url: Option<String>,


Will we need to hand on to this URL for the duration of the program and/or output it at some point? Or is it only a temporary variable so we can make a request to the GitHub API? (see more comments below)

0xazure · 2018-12-19T03:02:49Z

src/lib.rs

+    value: Option<String>,
+}
+
+impl fmt::Display for Languages {


You probably don't need to implement your own fmt::Display for Languages unless you're going to be pretty-printing out instances of struct Languages, and #[derive(Debug)] is usually sufficient for debugging, which you can access with the "{:?}" format string like so:

println!("{:?}", lang);

The only reason fmt::Dsiplay is implemented for Repository is because we wanted full control of the desired output format, namely only printing the description if it exists. The derived Debug implementation is pretty good, it's just that it'll print e.g. description: None if Option<String> is None which isn't what we wanted for Repository.

0xazure · 2018-12-19T03:27:55Z

src/lib.rs

+        let ref mut next = star.repo.languages_url;
+        if let Some(ref link) = next{
+            let mut res = client.get(link).send()?;
+            next = &mut extract_link_next(res.headers());


I don't think it makes sense to try and extract Next here because there is no Next header in the response:

Access-Control-Allow-Origin: * Access-Control-Expose-Headers: ETag, Link, Location, Retry-After, X-GitHub-OTP, X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Reset, X-OAuth-Scopes, X-Accepted-OAuth-Scopes, X-Poll-Interval, X-GitHub-Media-Type Cache-Control: public, max-age=60, s-maxage=60 Content-Encoding: gzip Content-Security-Policy: default-src 'none' Content-Type: application/json; charset=utf-8 Date: Wed, 19 Dec 2018 03:21:55 GMT ETag: W/"d6483279641fa22081ee4bc2044d6739" Last-Modified: Tue, 18 Dec 2018 22:37:04 GMT Referrer-Policy: origin-when-cross-origin, strict-origin-when-cross-origin Server: GitHub.com Status: 200 OK Strict-Transport-Security: max-age=31536000; includeSubdomains; preload Transfer-Encoding: chunked Vary: Accept X-Content-Type-Options: nosniff X-Frame-Options: deny X-GitHub-Media-Type: unknown, github.v3 X-GitHub-Request-Id: FC2C:6CCE:19C4CD3:4200EB7:5C19B93D X-RateLimit-Limit: 60 X-RateLimit-Remaining: 52 X-RateLimit-Reset: 1545191215 X-XSS-Protection: 1; mode=block Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8 Accept-Encoding: gzip, deflate, br Accept-Language: en-US,en;q=0.5 Connection: keep-alive Host: api.github.com Referer: https://api.github.com/ Upgrade-Insecure-Requests: 1 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0

The extract_link_next function is used to handle the pagination on the starred API endpoint:

Status: 200 OK Link: <https://api.github.com/resource?page=2>; rel="next", <https://api.github.com/resource?page=5>; rel="last"

which the languages API endpoint does not have.

0xazure · 2018-12-19T03:29:52Z

src/lib.rs

    full_name: String,
    description: Option<String>,
    stargazers_count: i32,
+    languages_url: Option<String>,


I'm not sure this needs to be an Option, the API always generates this URL. However, we will have to handle the case where there are no languages associated with a given repository (i.e. the json response is an empty object).

0xazure · 2018-12-19T03:32:00Z

src/lib.rs

            write!(f, " - {}", description)?;
        }

+        if let Some(ref languages_url) = self.languages_url {


This fmt::Display controls the output format of the Repository, and how these objects are written to stdout or a file. Is the languages_url a piece of data that should be written out along with the repo name, url, and project description?

0xazure · 2018-12-19T03:49:25Z

src/lib.rs


-pub fn collect_stars(config: Config) -> Result<(), Box<dyn error::Error>> {
+#[derive(Debug, Deserialize)]
+struct Languages {


I get what you're going for here, but unfortunately this isn't how serde works. With this struct definition, serde expects the json response to contain one or more objects of the following structure:

{ "key": "string data", "value": "string data" }

whereas the data we actually get back from the languages API endpoint is:

{ "Python": 597727, "JavaScript": 38865, "CSS": 1229, "Batchfile": 838, "Shell": 713, "HTML": 478 }

Now, because we don't know what languages a given repo will contain, and it would be a lot of work and not very flexible to write a struct that has keys for every language GitHub understands, I would really recommend looking into how serde works with untyped json values; the Value::Object type in particular should be of some use because it acts like a Map and we can iterate over its contents without needing to know anything about its keys. See the serde examples for an explanation of how it works exactly.

0xazure · 2018-12-19T03:55:17Z

src/lib.rs


+    let mut langs: Vec<Languages> = Vec::new();
+
+    for star in stars.iter(){


I think you've overcomplicated this part. To get the languages for all the starred repositories, we want to:

loop over the stars vector

for each star:

get its languages_url

send a request to that url using client.get(url)

parse the json result (see above about serde and untyped json)

store the parsed data into the star's Repository object

The stars vector is already mutable, so the Repository data can be updated (maybe add a function or two to Repository to handle this?), you'll just have to decide how you want to display this data and any calculations you do with the data to the user.

0xazure · 2018-12-19T03:57:27Z

src/lib.rs

+    }
+}
+
+pub fn collect_stars(config: Config) -> Result<(), Box<dyn error::Error>> { //Where the json extraction happens


Suggested change

pub fn collect_stars(config: Config) -> Result<(), Box<dyn error::Error>> { //Where the json extraction happens

pub fn collect_stars(config: Config) -> Result<(), Box<dyn error::Error>> {

nit: extraneous comment

Trying to pull a json object within a json object using a passed url …

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WIP - Pulling a JSON object from a given Starred repo URL#42

WIP - Pulling a JSON object from a given Starred repo URL#42
Mordax wants to merge 1 commit into0xazure:masterfrom
Mordax:issue-37

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		let mut langs: Vec<Languages> = Vec::new();

		for star in stars.iter(){

	pub fn collect_stars(config: Config) -> Result<(), Box<dyn error::Error>> { //Where the json extraction happens
	pub fn collect_stars(config: Config) -> Result<(), Box<dyn error::Error>> {

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