Enum rmoods_backend::reddit::model::listing::KindContainer

pub enum KindContainer {
    Listing(Box<RedditListing>),
    More(Box<MoreData>),
    T1(Box<Comment>),
    T2(Box<UserInfo>),
    T3(Box<Post>),
    T4(Box<Value>),
    T5(Box<SubredditInfo>),
    T6(Box<Value>),
}

Represents a generic Reddit data container.

Reddit API uses a special structure to represent varying types of object in a uniform way. This struct is actually the heart of the Reddit response parsing.

How does it work?

It’s kind of a declarative way to parse the response. The KindContainer struct described the universal structure of every Reddit response. Reddit uses the following structure to let us know what type of data to expect:

{
    "kind" : "t1",
    "data" : {
        <Comment data>
    }
}

So, we have a kind field and the corresponding data field, which has an object of the type indicated by kind.

Serde provides a convenient macro, that lets us describe how our enum should be handled in serialization/deserialization:

#[serde(tag = "kind", content = "data")]
enum Foo {}

When used like in the example above, this macro lets us represent our exact structure: object tagged by kind with the content in data. Content is the value embedded in the enum variant, eg. Box<RedditListing>.

Each field uses the #[serde(rename = "foo")] macro, to tell Serde to look for that given name during its operations. This paired with the previously described tagging, lets us use the KindContainer struct to recrusively, automatically and reliably parse all Reddit responses.

Example

Probably not accurate execution order, written just to understand the process.

1. We tell serde to deserialize some JSON data into KindContainer.
2. Serde looks for the kind field.
3. Let’s assume kind: "t1".
4. Since kind is "t1", serde knows that the enum variant it encountered is KindContainer::T1(Box)
5. Serde finds the data field and treats it as the content of type Box
6. Box is transparent to serde, so it parses the data field as a Comment

Recursive case

For the KindContainer::Listing, this works recursively, since RedditListing is basically a list of KindContainers.

Variants

Listing(Box<RedditListing>)

More(Box<MoreData>)

T1(Box<Comment>)

T2(Box<UserInfo>)

T3(Box<Post>)

T4(Box<Value>)

T5(Box<SubredditInfo>)

T6(Box<Value>)

Trait Implementations

impl Clone for KindContainer

fn clone(&self) -> KindContainer

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for KindContainer

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for KindContainer

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for KindContainer

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.