[−][src]Struct juniper_eager_loading::HasManyThrough
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 | The database model type | models::{name of contained type} | model = "models::Car" |
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" |
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>
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pub fn try_unwrap(&self) -> Result<&Vec<T>, Error>
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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)
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Add the loaded value to the list.
pub fn assert_loaded_otherwise_failed(&mut self)
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This function doesn't do anything since the default is an empty list and there is no error state.
Trait Implementations
impl<T: Eq> Eq for HasManyThrough<T>
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impl<T: Ord> Ord for HasManyThrough<T>
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fn cmp(&self, other: &HasManyThrough<T>) -> Ordering
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fn max(self, other: Self) -> Self
1.21.0[src]
Compares and returns the maximum of two values. Read more
fn min(self, other: Self) -> Self
1.21.0[src]
Compares and returns the minimum of two values. Read more
fn clamp(self, min: Self, max: Self) -> Self
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clamp
)Restrict a value to a certain interval. Read more
impl<T: PartialEq> PartialEq<HasManyThrough<T>> for HasManyThrough<T>
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fn eq(&self, other: &HasManyThrough<T>) -> bool
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fn ne(&self, other: &HasManyThrough<T>) -> bool
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impl<T: Clone> Clone for HasManyThrough<T>
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fn clone(&self) -> HasManyThrough<T>
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fn clone_from(&mut self, source: &Self)
1.0.0[src]
Performs copy-assignment from source
. Read more
impl<T: PartialOrd> PartialOrd<HasManyThrough<T>> for HasManyThrough<T>
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fn partial_cmp(&self, other: &HasManyThrough<T>) -> Option<Ordering>
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fn lt(&self, other: &HasManyThrough<T>) -> bool
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fn le(&self, other: &HasManyThrough<T>) -> bool
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fn gt(&self, other: &HasManyThrough<T>) -> bool
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fn ge(&self, other: &HasManyThrough<T>) -> bool
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impl<T> Default for HasManyThrough<T>
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impl<T: Debug> Debug for HasManyThrough<T>
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Auto Trait Implementations
impl<T> Send for HasManyThrough<T> where
T: Send,
T: Send,
impl<T> Sync for HasManyThrough<T> where
T: Sync,
T: Sync,
Blanket Implementations
impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
fn to_owned(&self) -> T
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fn clone_into(&self, target: &mut T)
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> From<T> for T
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impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
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impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
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impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,