Struct juniper_eager_loading::HasMany

pub struct HasMany<T>(_);

A "has many" association.

Imagine you have these models:

struct User {
    id: i32,
}

struct Car {
    id: i32,
    user_id: i32,
}

For this setup we say "user has many cars" and "cars have one user". This is the inverse of a HasOne assocation because the foreign key is on Car instead of User.

This means users can own many cars, but cars can only be owned by one user.

Example

You can find a complete example of HasMany here.

Attributes

Name	Description	Default	Example
foreign_key_field	The name of the foreign key field	{name of struct}_id	foreign_key_field = user_id
foreign_key_optional	The foreign key type is optional	Not set	foreign_key_optional
root_model_field	The name of the field on the associated GraphQL type that holds the database model	N/A (unless using skip)	root_model_field = "car"
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	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> HasMany<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.

Trait Implementations

impl<T> Association<T> for HasMany<T>

fn loaded_child(&mut self, child: T)

Store the loaded child on the association.

fn assert_loaded_otherwise_failed(&mut self)

The association should have been loaded by now, if not store an error inside the association (if applicable for the particular association).

impl<T: Clone> Clone for HasMany<T>

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

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T> Default for HasMany<T>

fn default() -> Self

Returns the "default value" for a type.

impl<T: Eq> Eq for HasMany<T>

impl<T: Ord> Ord for HasMany<T>

fn cmp(&self, other: &HasMany<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<HasMany<T>> for HasMany<T>

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

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

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

This method tests for !=.

impl<T: PartialOrd> PartialOrd<HasMany<T>> for HasMany<T>

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

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

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

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

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

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

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

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

fn ge(&self, other: &HasMany<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 HasMany<T>

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

Formats the value using the given formatter.

impl<T> StructuralPartialEq for HasMany<T>

impl<T> StructuralEq for HasMany<T>