orm

Documentation

Index

• func BuildObjectIndex(objects []base.Object) (map[reflect.Type]*Table, error)
• type Client
  • func NewClient(conn Connector, objects ...base.Object) (Client, error)
• type Connector
• type Iterator
• type Table
  • func TableFromObject(e base.Object) (*Table, error)
  • func (t *Table) GetKeyRowFromObject(e base.Object) []base.Column
  • func (t *Table) GetPartitionKeyRowFromObject(e base.Object) []base.Column
  • func (t *Table) GetRowFromObject(e base.Object, selectedFields ...string) []base.Column
  • func (t *Table) SetObjectFromRow(e base.Object, row []base.Column)

Functions

func BuildObjectIndex

func BuildObjectIndex(objects []base.Object) (
	map[reflect.Type]*Table, error)

BuildObjectIndex builds an index to map storage object type to its Table representation

Types

type Client

type Client interface {
	// CreateIfNotExists creates the storage object in the database if it
	// doesn't already exist
	CreateIfNotExists(ctx context.Context, e base.Object) error
	// Create creates the storage object in the database
	Create(ctx context.Context, e base.Object) error
	// Get gets the storage object from the database
	Get(ctx context.Context, e base.Object, fieldsToRead ...string) (
		map[string]interface{}, error)
	// GetAll gets all the storage objects for the partition key from the
	// database
	GetAll(ctx context.Context, e base.Object) ([]map[string]interface{}, error)
	// GetAllIter provides an iterative way to fetch all storage objects
	// for the partition key
	GetAllIter(ctx context.Context, e base.Object) (Iterator, error)
	// Update updates the storage object in the database
	// The fields to be updated can be specified as fieldsToUpdate which is
	// a variable list of field names and is to be optionally specified by
	// the caller. If not specified, all fields in the object will be updated
	// to the DB
	Update(ctx context.Context, e base.Object, fieldsToUpdate ...string) error
	// Delete deletes the storage object from the database
	Delete(ctx context.Context, e base.Object) error
}

Client defines the methods to operate with storage objects

func NewClient

func NewClient(conn Connector, objects ...base.Object) (Client, error)

NewClient returns a new ORM client for the base instance and connector provided.

type Connector

type Connector interface {
	// CreateIfNotExists creates a row in the DB for the base object if it
	// doesn't already exist
	CreateIfNotExists(
		ctx context.Context,
		e *base.Definition,
		values []base.Column,
	) error

	// Create creates a row in the DB for the base object
	Create(ctx context.Context, e *base.Definition, values []base.Column) error

	// Get fetches a row by primary key of base object
	Get(
		ctx context.Context,
		e *base.Definition,
		keys []base.Column,
		colNamesToRead ...string,
	) (map[string]interface{}, error)

	// GetAll fetches a list of base objects for the partition key
	// and the given clustering keys
	GetAll(
		ctx context.Context,
		e *base.Definition,
		keys []base.Column,
	) ([]map[string]interface{}, error)

	GetAllIter(
		ctx context.Context,
		e *base.Definition,
		keys []base.Column,
	) (Iterator, error)

	// Update updates a row in the DB for the base object
	Update(
		ctx context.Context,
		e *base.Definition,
		values []base.Column,
		keys []base.Column,
	) error

	// Delete deletes a row from the DB for the base object
	Delete(ctx context.Context, e *base.Definition, keys []base.Column) error
}

Connector is the interface that must be implemented for a backend service

type Iterator

type Iterator interface {
	// Next fetches the next row of the result. On reaching the end of
	// results, it returns nil. Error is returned if there is a failure
	// during iteration. Next should not be called once error is returned
	// or Close is called.
	Next() ([]base.Column, error)

	// Close indicates that iterator is no longer required and so any
	// clean-up actions may be performed.
	Close()
}

Iterator allows the caller to iterate over the results of a query.

type Table

type Table struct {
	base.Definition

	// map from DB column name -> object field name
	ColToField map[string]string

	// map of base field name to DB column name
	FieldToCol map[string]string
}

Table is an ORM internal representation of storage object. Storage object is translated into Definition that contains the primary key information as well as column to datatype map It also contains maps used to translate storage object fields into DB columns and viceversa and this is used during read and write operations

func TableFromObject

func TableFromObject(e base.Object) (*Table, error)

TableFromObject creates a orm.Table from a storage.Object instance.

func (*Table) GetKeyRowFromObject

func (t *Table) GetKeyRowFromObject(
	e base.Object) []base.Column

GetKeyRowFromObject is a helper for generating a row of partition and clustering key column values to be used in a select query.

func (*Table) GetPartitionKeyRowFromObject

func (t *Table) GetPartitionKeyRowFromObject(
	e base.Object) []base.Column

GetPartitionKeyRowFromObject is a helper for generating a row of partition key column values to be used in a GetAll query.

func (*Table) GetRowFromObject

func (t *Table) GetRowFromObject(
	e base.Object,
	selectedFields ...string,
) []base.Column

GetRowFromObject is a helper for generating a row from the storage object selectedFields will be used to restrict the number of columns in that row This will be used to convert only select fields of an object to a row. selectedFields if empty will be ignored. It will be empty in case this function is called when handling Create operation since in that case, all fields of the object must be converted to a row. Update can be used to update specific fields of the object

func (*Table) SetObjectFromRow

func (t *Table) SetObjectFromRow(e base.Object, row []base.Column)

SetObjectFromRow is a helper for populating storage object from the given row