Struct json_api::view::Context

pub struct Context<'v> { /* fields omitted */ }

A data structure containing render context that can be "forked" and passed to a child context.

This struct is helpful if you want recursively call Resource::to_object to render a document's primary data and included resources.

Since the Context struct requires a mutable (unique) reference to a document's included resources, only one context can be operated on at a time. In other words, if you want to access a context, it cannot have any children in scope. Since you can only operate on a single context at time, a recursive implementation of included resources and sparse field-sets is much easier.

Methods

impl<'v> Context<'v>

fn new(
    kind: Key,
    query: Option<&'v Query>,
    included: &'v mut Set<Object>
) -> Self

Creates a new, root context.

This constructor can only be used when creating a root context. A child context can be created with the fork method.

Example

use json_api::value::Set;
use json_api::view::Context;

let mut included = Set::new();
let mut ctx = Context::new("posts".parse()?, None, &mut included);

fn field(&self, name: &str) -> bool

Returns true if the field name is present in the current context's field-set or the current context's field-set does not exist.

fn fork(&mut self, kind: Key, key: &Key) -> Context

Creates a new child context from self.

fn include(&mut self, value: Object) -> bool

Adds the value to the context's included resource set.

If the set did not have this value present, true is returned.

If the set did have this value present, false is returned.

fn included(&self) -> bool

Returns true if the context is valid with respect to parent context(s).

If there is no parent context (i.e the current context represents the primary data of the document), this will always return false.

if there is a parent context and this function returns false, this context can should be ignored.

Trait Implementations

impl<'v> Debug for Context<'v>

fn fmt(&self, __arg_0: &mut Formatter) -> Result

Formats the value using the given formatter.