dataloader

README

Dataloader

DataLoader struct to avoiding N+1 queries when resolving graphql objects.

N+1 queries are a performance problem in which the application makes database queries in a loop, instead of making a single query that returns or modifies all the information at once. Each database connection takes some amount of time, so querying the database in a loop can be many times slower than doing it just once.

Documentation

Index

• type BatchLoader
• type DataLoader
  • func NewDataLoader[K string, T any](ctx context.Context, batchLoader BatchLoader[K, T], maxBatchSize int32, ...) *DataLoader[K, T]
  • func (d *DataLoader[K, T]) Load(key K) (*T, error)
  • func (d *DataLoader[K, T]) LoadMany(keys *[]K) ([]*T, error)

Types

type BatchLoader

type BatchLoader[K string | int, T any] interface {
	// Batch function that is called with a list of keys. This function should return a map of values for each passed key.
	// Should be implemented by the user.
	BatchLoad(ctx context.Context, keys *[]K) (map[K]*T, error)
}

type DataLoader

type DataLoader[K string, T any] struct {
	// contains filtered or unexported fields
}

func NewDataLoader

func NewDataLoader[K string, T any](ctx context.Context, batchLoader BatchLoader[K, T], maxBatchSize int32, maxBatchTimeMs int32) *DataLoader[K, T]

func (*DataLoader[K, T]) Load

func (d *DataLoader[K, T]) Load(key K) (*T, error)

Load retrieves a value for a given key. If the value is not already cached, the loader will call the batch function with a list of keys.

func (*DataLoader[K, T]) LoadMany

func (d *DataLoader[K, T]) LoadMany(keys *[]K) ([]*T, error)

LoadMany retrieves multiple values for a given list of keys. For each key that is not already cached, a single loader call will be scheduled.