MySqlPersistence

Implements: IReferenceable, IUnreferenceable, IConfigurable, IOpenable, ICleanable

Description

The MySqlPersistence[T] class allows you to create persistence components that store data in MySQL databases using the official driver.

Important points

• This is the most basic persistence component that is only able to store data items of any type. Specific CRUD operations over the data items must be implemented in child classes by accessing this._db or this._collection properties.

Configuration parameters

• table: (optional) MySQL table name

• schema: (optional) MySQL schema name

• connection(s):

  • discovery_key: (optional) key to retrieve the connection from IDiscovery
  • host: host name or IP address
  • port: port number (default: 27017)
  • uri: resource URI or connection string with all parameters in it

• credential(s):

  • store_key: (optional) key to retrieve the credentials from ICredentialStore
  • username: (optional) username
  • password: (optional) user’s password

• options:

  • connect_timeout: (optional) number of milliseconds to wait before timing out when connecting a new client (default: 0)
  • idle_timeout: (optional) number of milliseconds a client must sit idle in the pool and not be checked out (default: 10000)
  • max_pool_size: (optional) maximum number of clients the pool should contain (default: 10)

References

• *:logger:*:*:1.0 - (optional) ILogger components to pass log messages
• *:discovery:*:*:1.0 - (optional) IDiscovery services
• *:credential-store:*:*:1.0 - (optional) ICredentialStore to resolve credentials

Constructors

InheritMySqlPersistence

InheritMySqlPersistence creates a new instance of the persistence component.

InheritMySqlPersistence[T any](overrides IMySqlPersistenceOverrides[T], tableName string) *MySqlPersistence[T]

• overrides: IMySqlPersistenceOverrides[T] - References to override virtual methods.
• tableName: string - (optional) table name.

Fields

Instance methods

Clear

Clears a component’s state.

(c *MySqlPersistence[T]) Clear(ctx context.Context, context IContext) error

• ctx: context.Context - operation context.
• context: IContext - (optional) a context to trace execution through a call chain.
• returns: error - error or nil no errors occurred.

ClearSchema

Clears all auto-created objects

(c *MySqlPersistence[T]) ClearSchema()

close

Closes a component and frees the used resources.

(c *MySqlPersistence[T]) Close(ctx context.Context, context IContext) (err error)

• ctx: context.Context - operation context.
• context: IContext - (optional) a context to trace execution through a call chain.
• returns: error - error or nil no errors occurred.

Configure

Configures component by passing configuration parameters.

(c *MySqlPersistence[T]) Configure(ctx context.Context, config *ConfigParams)

• ctx: context.Context - operation context.
• config:: *ConfigParams - configuration parameters to be set.

ConvertFromPublic

Converts object value from public to internal format.

(c *MySqlPersistence[T]) ConvertFromPublic(value T) (map[string]any, error)

• value: T - object in public format to convert.
• returns: (map[string]any, error) - converted object in internal format.

ConvertToPublic

Converts object value from internal to public format.

(c *MySqlPersistence[T]) ConvertToPublic(rows *sql.Rows) (T, error)

• rows: *sql.Rows - object in internal format to convert.
• returns: T - converted object in public format.

Create

Creates a data item.

(c *MySqlPersistence[T]) Create(ctx context.Context, context IContext, item T) (result T, err error)

• ctx: context.Context - operation context.
• context: IContext - (optional) a context to trace execution through a call chain.
• item: T - item to be created.
• returns: (result T, err error) - created item.

CreateSchema

Checks if a table exists and if not, it creates the necessary database objects.

(c *MySqlPersistence[T]) CreateSchema(ctx context.Context, context IContext) (err error)

• ctx: context.Context - operation context.
• context: string - (optional) a context to trace execution through a call chain.
• returns: error - created item.

DefineSchema

Defines database schema via auto create objects or convenience methods.

(c *MySqlPersistence[T]) DefineSchema()

DeleteByFilter

Deletes data items that match to a given filter. This method shall be called by a public deleteByFilter method from child class that receives FilterParams and converts them into a filter function.

(c *MySqlPersistence[T]) DeleteByFilter(ctx context.Context, context IContext, filter string) error

• ctx: context.Context - operation context.
• context: string - (optional) a context to trace execution through a call chain.
• filter: any - (optional) filter function to filter items.
• returns: error - error or nil for success.

EnsureIndex

Adds index definition to create it on opening.

(c *MySqlPersistence[T]) EnsureIndex(name string, keys map[string]string, options map[string]string)

• name: string - index name.
• keys: any - index keys (fields).
• options: any - index options.

EnsureSchema

Adds a statement to schema definition.

(c *MySqlPersistence[T]) EnsureSchema(schemaStatement string)

• schemaStatement: string - statement to be added to the schema

GenerateColumns

Generates a list of column names to use in SQL statements like: “column1,column2,column3”.

(c *MySqlPersistence[T]) GenerateColumns(columns []string) string

• columns: []string - array with column values or a key-value map
• returns: string - generated list of column names

GenerateParameters

Generates a list of value parameters to use in SQL statements like: "?,?,?"

(c *MySqlPersistence[T]) GenerateParameters(valuesCount int) string

• valuesCount: int - array with values or a key-value map
• returns: string - generated list of value parameters

GenerateSetParameters

Generates a list of column sets to use in UPDATE statements like: column1=$1,column2=$2

(c *MySqlPersistence[T]) GenerateSetParameters(columns []string) string

• columns: []string - key-value map with columns and values
• returns: string - generated list of column sets

GenerateColumnsAndValues

GenerateColumnsAndValues generates a list of column parameters

(c *MySqlPersistence[T]) GenerateColumnsAndValues(objMap map[string]any) ([]string, []any)

• objMap: map[string]any - key-value map with columns and values
• returns: ([]string, []any) - generated list of column values

GetCountByFilter

Gets a number of data items retrieved by a given filter.

This method shall be called by a public getCountByFilter method from the child class that receives FilterParams and converts them into a filter function.

(c *MySqlPersistence[T]) GetCountByFilter(ctx context.Context, context IContext, filter string) (int64, error)

• ctx: context.Context - operation context.
• context: IContext - (optional) a context to trace execution through a call chain.
• filter: string - (optional) JSON object filter
• returns: (int64, error) - number of filtered items.

GetListByFilter

Gets a list of data items retrieved by a given filter and sorted according to sort parameters.

This method shall be called by a public GetListByFilter method from a child class that receives FilterParams and converts them into a filter function.

(c *MySqlPersistence[T]) GetListByFilter(ctx context.Context, context IContext, filter string, sort string, selection string) (items []T, err error)

• ctx: context.Context - operation context.
• context: string - (optional) a context to trace execution through a call chain.
• filter: string - (optional) filter function to filter items
• sort: string - (optional) sorting parameters
• select: string - (optional) projection parameters (not used yet)
• returns: (items []T, err error) - data list of results by filter.

GetOneRandom

Gets a random item from items that match to a given filter.

This method shall be called by a public GetOneRandom method from a child class that receives FilterParams and converts them into a filter function.

(c *MySqlPersistence[T]) GetOneRandom(ctx context.Context, context IContext, filter string) (item T, err error)

• ctx: context.Context - operation context.
• context: IContext - (optional) a context to trace execution through a call chain.
• filter: string - (optional) a filter JSON object
• returns: (item T, err error) - a random item.

GetPageByFilter

Gets a page of data items retrieved by a given filter and sorted according to sort parameters.

This method shall be called by a public GetPageByFilter method from the a child class that receives FilterParams and converts them into a filter function.

(c *MySqlPersistence[T]) GetPageByFilter(ctx context.Context, context IContext, filter string, paging PagingParams, sort string, selection string) (page DataPage[T], err error)

• ctx: context.Context - operation context.
• context: IContext - (optional) a context to trace execution through a call chain.
• filter: string - (optional) filter for JSON objects.
• paging: PagingParams - (optional) paging parameters
• sort: string - (optional) sorting JSON object
• select: string - (optional) projection JSON object
• returns: (page DataPage[T], err error) - a data page of result by filter

IsOpen

Checks if the component is opened.

(c *MySqlPersistence[T]) IsOpen() bool

• returns: bool - True if the component has been opened and False otherwise.

open

Opens the component.

(c *MySqlPersistence[T]) Open(ctx context.Context, context IContext) (err error)

• ctx: context.Context - operation context.
• context: IContext - (optional) a context to trace execution through a call chain.
• returns: error - error or nil no errors occurred.

QuoteIdentifier

Adds single quotes to a string.

(c *MySqlPersistence[T]) QuoteIdentifier(value string) string

• value: string - string where quotes need to be added
• returns: string - string with added quotes

QuotedTableName

Joins schema and database name in dot notation

(c *MySqlPersistence[T]) QuotedTableName() string

• returns: string - string with added quotes

SetReferences

Sets references to dependent components.

(c *MySqlPersistence[T]) SetReferences(ctx context.Context, references IReferences)

• ctx: context.Context - operation context.
• references: IReferences - references to locate the component dependencies.

UnsetReferences

Unsets (clears) previously set references to dependent components.

(c *MySqlPersistence[T]) UnsetReferences()

Examples

import (
	"context"
	"fmt"

	cconf "github.com/pip-services3-gox/pip-services3-commons-gox/config"
	cpersist "github.com/pip-services3-gox/pip-services3-data-gox/persistence"
	persist "github.com/pip-services3-gox/pip-services3-mysql-gox/persistence"
	"github.com/pip-services3-gox/pip-services3-mysql-gox/test/fixtures"
)

type MyMySqlPersistence struct {
	*persist.MySqlPersistence[fixtures.Dummy]
}

func NewMyMySqlPersistence() *MyMySqlPersistence {
	c := &MyMySqlPersistence{}
	c.MySqlPersistence = persist.InheritMySqlPersistence[fixtures.Dummy](c, "mydata")
	return c
}

func (c *MyMySqlPersistence) GetOneByName(ctx context.Context, context IContext, name string) (item fixtures.Dummy, err error) {

	query := "SELECT * FROM " + c.QuotedTableName() + " WHERE name=?"

	rows, err := c.Client.QueryContext(ctx, query, name)
	if err != nil {
		return item, err
	}
	defer rows.Close()

	if !rows.Next() {
		return item, rows.Err()
	}

	if err == nil {
		return c.Overrides.ConvertToPublic(rows)
	}
	return item, err
}

func (c *MyMySqlPersistence) Set(ctx context.Context, context IContext, item fixtures.Dummy) (result fixtures.Dummy, err error) {
	objMap, convErr := c.Overrides.ConvertFromPublic(item)
	if convErr != nil {
		return result, convErr
	}

	columns, values := c.GenerateColumnsAndValues(objMap)

	paramsStr := c.GenerateParameters(len(values))
	columnsStr := c.GenerateColumns(columns)
	setParams := c.GenerateSetParameters(columns)
	id := cpersist.GetObjectId(objMap)

	values = append(values, values...)

	query := "INSERT INTO " + c.QuotedTableName() + " (" + columnsStr + ") VALUES (" + paramsStr + ")"
	query += " ON DUPLICATE KEY UPDATE " + setParams

	_, err = c.Client.ExecContext(ctx, query, values...)
	if err != nil {
		return result, err
	}

	// Getting result
	query = "SELECT * FROM " + c.QuotedTableName() + " WHERE id=?"
	rows, err := c.Client.QueryContext(ctx, query, []any{id}...)
	if err != nil {
		return result, err
	}
	defer rows.Close()

	if !rows.Next() {
		return result, rows.Err()
	}

	if err == nil {
		result, convErr = c.Overrides.ConvertToPublic(rows)
		if convErr != nil {
			return result, convErr
		}
		return result, nil
	}
	return result, rows.Err()

}

func main() {
	persistence := NewMyMySqlPersistence()
	persistence.Configure(context.Background(), cconf.NewConfigParamsFromTuples(
		"host", "localhost",
		"port", 27017,
	))

	err := persistence.Open(context.Background(), "123")

	res, err := persistence.Set(context.Background(), "123", MyData{Id: "1", Name: "ABC"})
	item, err := persistence.GetOneByName(context.Background(), "123", "ABC")
	fmt.Println(item) // Result: { Id: "1", Name: "ABC" }
}