Struct juniper_eager_loading::HasManyThrough

pub struct HasManyThrough<T>(_);

A "has many through" association.

Imagine you have these models:

struct User {
    id: i32,
}

struct Company {
    id: i32,
}

struct Employments {
    id: i32,
    user_id: i32,
    company_id: i32,
}

For this setup we say "user has many companies through employments". This means uses can work at many companies and companies can have many employees, provided that we join with Employment.

This requires that we use the JoinModel type on EagerLoadChildrenOfType and is therefore a bit different from the other associations since it involves a third type.

Example

You can find a complete example of HasManyThrough here.

Attributes

Name	Description	Default	Example
model_field	The field on the contained type that holds the model	{name of contained type} in snakecase	model_field = "company"
join_model	The model we have to join with	N/A	join_model = "models::Employment"
join_model_field	The field on the join model type that holds the model	{name of join model type} in snakecase	join_model_field = "employment"
foreign_key_field	The field on the join model that contains the parent models id	{name of parent type in lowercase}_id	foreign_key_field = "car_id"
graphql_field	The name of this field in your GraphQL schema	{name of field}	graphql_field = "country"
predicate_method	Method used to filter child associations. This can be used if you only want to include a subset of the models. This method will be called to filter the join models.	N/A (attribute is optional)	predicate_method = "a_predicate_method"

Errors

try_unwrap will never error. If the association wasn't loaded or wasn't found it will return Ok(vec![]).

Methods

impl<T> HasManyThrough<T>

pub fn try_unwrap(&self) -> Result<&Vec<T>, Error>

Borrow the loaded values. If no values have been loaded it will return an empty list. It will not return an error.

pub fn loaded(&mut self, inner: T)

Add the loaded value to the list.

pub fn assert_loaded_otherwise_failed(&mut self)

This function doesn't do anything since the default is an empty list and there is no error state.

Trait Implementations

impl<T: Clone> Clone for HasManyThrough<T>

fn clone(&self) -> HasManyThrough<T>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T> Default for HasManyThrough<T>

fn default() -> Self

Returns the "default value" for a type.

impl<T: Eq> Eq for HasManyThrough<T>

impl<T: Ord> Ord for HasManyThrough<T>

fn cmp(&self, other: &HasManyThrough<T>) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

🔬 This is a nightly-only experimental API. (clamp)

Restrict a value to a certain interval.

impl<T: PartialEq> PartialEq<HasManyThrough<T>> for HasManyThrough<T>

fn eq(&self, other: &HasManyThrough<T>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &HasManyThrough<T>) -> bool

This method tests for !=.

impl<T: PartialOrd> PartialOrd<HasManyThrough<T>> for HasManyThrough<T>

fn partial_cmp(&self, other: &HasManyThrough<T>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &HasManyThrough<T>) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &HasManyThrough<T>) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &HasManyThrough<T>) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &HasManyThrough<T>) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<T: Debug> Debug for HasManyThrough<T>

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

Formats the value using the given formatter.