PostgresPersistence

Abstract persistence component that stores data in PostgreSQL using the official driver.

Implements: IReferenceable, IUnreferenceable, IConfigurable, IOpenable, ICleanable

Description

The PostgresPersistence class allows you to create persistence components that store data in PostgreSQL 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 c.Db or c.Collection properties.

Configuration parameters

  • collection: (optional) PostgreSQL collection 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 can 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) credential stores to resolve credentials

Constructors

InheritPostgresPersistence

Creates a new instance of the persistence component.

InheritPostgresPersistence[T any](overrides IPostgresPersistenceOverrides[T], tableName string) *PostgresPersistence

Fields

TableName

The PostgreSQL table name.

TableName: string

DependencyResolver

The dependency resolver.

DependencyResolver: *DependencyResolver

Logger

The logger.

Logger: *CompositeLogger

_connection

The PostgreSQL connection component.

Connection: *PostgresConnection

Client

The PostgreSQL connection pool object.

Client: *pgxpool.Pool

DatabaseName

The PostgreSQL database name.

DatabaseName: string

MaxPageSize

The maximum number of records to return from the database.

MaxPageSize: int

Methods

Clear

Clears a component’s state.

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

  • ctx: context.Context - operation context.
  • context: IContext- a context to trace execution through a call chain.
  • returns: error - returns error if not received.

ClearSchema

Clears all auto-created objects.

(c *PostgresPersistence[T]) ClearSchema()

Close

Closes the component and frees used resources.

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

  • ctx: context.Context - operation context.
  • context: IContext- a context to trace execution through a call chain.
  • returns: (err error) - returns error if not received.

Configure

Configures the component.

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

  • ctx: context.Context - operationcontext.
  • config: *conf.ConfigParams - configuration parameters to set.

ConvertFromPublic

Converts an object value from public to internal format.

(c *PostgresPersistence[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.

ConvertFromPublicPartial

Converts the given object from the public partial format.

(c *PostgresPersistence[T]) ConvertFromPublicPartial(value map[string]any) (map[string]any, error)

  • value: map[string]any - the object to convert from the public partial format.
  • returns: (map[string]any, error) - the initial object.

ConvertToPublic

Converts an object value from internal to public format.

(c *PostgresPersistence[T]) ConvertToPublic(rows pgx.Rows) T

  • item: pgx.Rows - object in internal format to convert.
  • returns: T - converted object in public format.

Create

Creates a data item.

(c *PostgresPersistence[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 it doesn’t, it creates the necessary database objects.

(c *PostgresPersistence[T]) CreateSchema(context IContext) (err error)

  • context: IContext - (optional) a context to trace execution through a call chain.
  • returns: (err error) - returns error if not received.

DefineSchema

Defines database schema via auto create objects or convenience methods.

(c *PostgresPersistence[T]) DefineSchema()

DeleteByFilter

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

(c *PostgresPersistence[T]) DeleteByFilter(ctx context.Context, context IContext, filter string) (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: (err error) - returns error if not received.

EnsureIndex

Adds index definition to create it on opening.

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

  • keys: map[string]string - index keys (fields)
  • options: map[string]string - index options

EnsureSchema

Adds a statement to schema definition.

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

  • values: []string - an array with column values.
  • returns: string - generated list of column names

GenerateColumnsAndValues

GenerateColumnsAndValues generates a list of column parameters

GenerateColumnsAndValues(objMap map[string]any) ([]string, []any)

  • values: map[string]any - an key-value map with column values.
  • returns: ([]string, []any) - a generated list of column values.

GenerateParameters

Generates a list of value parameters to use in SQL statements like: "$1,$2,$3".

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

  • values: int - count of generate parameters.
  • returns: string - generated list of value parameters

GenerateSetParameters

Generates a list of column sets to use in UPDATE statements like: "$1,$2,$3".

(c *PostgresPersistence[T]) GenerateSetParameters(values []string) string

  • values: []string - an array with column values.
  • returns: string - generated list of column sets

GenerateValues

Generates a list of column parameters.

(c *PostgresPersistence[T]) GenerateValues(columns string, values interface{}) []interface{}

  • values: interface{} - key-value map with columns and values
  • returns: []interface{} - generated list of column values

GetCountByFilter

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

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

(c *PostgresPersistence[T]) GetCountByFilter(ctx context.Context, context IContext, filter string) (count int64, err 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: (count int64, err 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 func GetListByFilter method from a child class that receives FilterParams and converts them into a filter function.

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

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

GetOneRandom

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

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

(c *PostgresPersistence[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) - 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 func GetPageByFilter method from a child class that receives FilterParams and converts them into a filter function.

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

  • context: IContext - (optional) a context to trace execution through a call chain.
  • filter: string - (optional) filter for JSON objects
  • paging: *cdata.PagingParams - (optional) paging parameters
  • sort: string - (optional) sorting JSON object
  • sel: string - (optional) projection JSON object
  • returns: (page *cdata.DataPage[T], err error) - data page with filtered result

IsOpen

Checks if the component is opened.

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

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

IsTerminated

IsTerminated checks if the wee need to terminate process before close component.

(c *PostgresPersistence[T]) IsTerminated() bool

  • returns: bool - true if you need terminate your processes.

Open

Opens the component.

(c *PostgresPersistence[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: (err error) - returns error if not received.

QuoteIdentifier

Adds a single quote to each side of the string.

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

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

SetReferences

Sets references to dependent components.

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

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

UnsetReferences

Unsets (clears) previously set references to dependent components.

(c *PostgresPersistence[T]) UnsetReferences()

QuotedTableName

Return quoted SchemaName with TableName (“schema”.“table”)

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

  • returns: string - quoted SchemaName.