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 this._db or this._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

Creates a new instance of the persistence component.

public constructor(tableName?: string)

  • tableName: string - (optional) table name.

Fields

_table_name

The PostgreSQL table object.

protected _table_name: string

_dependencyResolver

The dependency resolver.

protected _dependencyResolver: DependencyResolver

_logger

The logger.

protected _logger: CompositeLogger

_connection

The PostgreSQL connection component.

protected _connection: PostgresConnection

_client

The PostgreSQL connection pool object.

protected _client: any

_databaseName

The PostgreSQL database name.

protected _databaseName: string

_tableName

The PostgreSQL table object.

protected _tableName: string

_maxPageSize

The maximum number of records to return from the database.

protected _maxPageSize = 100

Instance methods

clear

Clears a component’s state.

public clear(correlationId: string): Promise<void>

  • correlationId: string- object to convert from the public partial format.

clearSchema

Clears all auto-created objects.

protected clearSchema(): void

close

Closes the component and frees used resources.

public close(correlationId: string): Promise<void>

  • correlationId: string- object to convert from the public partial format.

configure

Configures the component.

public configure(config: ConfigParams): void

  • correlationId: string- the object to convert from the public partial format.

convertFromPublic

Converts an object value from public to internal format.

protected convertFromPublic(value: any): any

  • value: any - object in public format to convert.
  • returns: any - converted object in internal format.

convertToPublic

Converts an object value from internal to public format.

protected convertToPublic(value: any): any

  • value: any - object in internal format to convert.
  • returns: any - converted object in public format.

create

Creates a data item.

public create(correlationId: string, item: T): Promise<T>

  • correlationId: string - (optional) transaction id used to trace execution through the call chain.
  • item: T - item to be created.
  • returns: Promise<T> - created item

createSchema

Checks if a table exists and if it doesn’t, it creates the necessary database objects.

protected createSchema(correlationId: string): Promise<void>

  • correlationId: string - (optional) transaction id used to trace execution through the call chain.

defineSchema

Defines database schema via auto create objects or convenience methods.

protected defineSchema(): void

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.

deleteByFilter(correlationId: string, filter: any): Promise<void>

  • correlationId: string - (optional) transaction id used to trace execution through the call chain.
  • filter: any - (optional) filter function used to filter items.

ensureIndex

Adds index definition to create it on opening.

protected ensureIndex(name: string, keys: any, options?: any): void

  • keys: any - index keys (fields)
  • options: any - index options

ensureSchema

Adds a statement to schema definition.

protected ensureSchema(schemaStatement: string): void

  • 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”.

protected generateColumns(values: any): string

  • values: any - 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: “%s,%s,%s”.

protected generateParameters(values: any): string

  • values: any - 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=%s,column2=%s.

protected generateSetParameters(values: any): string

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

generateValues

Generates a list of column parameters.

protected generateValues(values: any): any[]

  • values: any - key-value map with columns and values
  • returns: 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 a child class that receives FilterParams and converts them into a filter function.

protected getCountByFilter(correlationId: string, filter: any): Promise<number>

  • correlationId: string - (optional) transaction id used to trace execution through the call chain.
  • filter: any - (optional) JSON object filter.
  • returns: Promise<number> - 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.

protected getListByFilter(correlationId: string, filter: any, sort: any, select: any): Promise<T[]>

  • correlationId: string - (optional) transaction id used to trace execution through the call chain.
  • filter: any - (optional) filter function to filter items
  • sort: any - (optional) sorting parameters
  • select: any - (optional) projection parameters (not used yet)
  • returns: Promise<T[]> - 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 public getOneRandom method from a child class that receives FilterParams and converts them into a filter function.

protected getOneRandom(correlationId: string, filter: any): Promise<T>

  • correlationId: string - (optional) transaction id used to trace execution through the call chain. filter: any
  • returns: Promise<T> - 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 a child class that receives FilterParams and converts them into a filter function.

protected getPageByFilter(correlationId: string, filter: any, paging: PagingParams, sort: any, select: any): Promise<DataPage>

  • correlationId: string - (optional) transaction id used to trace execution through a call chain.
  • filter: any - (optional) filter for JSON objects
  • paging: PagingParams - (optional) paging parameters
  • sort: any - (optional) sorting JSON object
  • select: any - (optional) projection JSON object
  • returns: Promise<DataPage> - data page with filtered result

isOpen

Checks if the component is opened.

isOpen(): boolean

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

open

Opens the component.

public open(correlationId: string): Promise<void>

  • correlationId: string - (optional) transaction id used to trace execution through the call chain.

quoteIdentifier

Adds a single quote to each side of the string.

protected 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.

public setReferences(references: IReferences): void

  • references: IReferences - references to locate the component dependencies.

unset_references

Unsets (clears) previously set references to dependent components.

public unsetReferences(): void

Examples

class MyPostgresPersistence extends PostgresPersistence<MyData> {
  public constructor() {
      base("mydata");
  }

  public getByName(correlationId: string, name: string): Promise<MyData> {
    let criteria = { name: name };
    return new Promise((resolve, reject) => {
      this._model.findOne(criteria, (err, item) => {
        if (err != null) {
          reject(err);
          return;
        }
        item = this.convertToPublic(item);
        resolve(item);
      });
     });
  }); 

  public set(correlatonId: string, item: MyData): Promise<MyData> {
    let criteria = { name: item.name };
    let options = { upsert: true, new: true };
    
    return new Promise((resolve, reject) => {
      this.findOneAndUpdate(criteria, item, options, (err, item) => {
        if (err != null) {
          reject(err);
          return;
        }
        item = this.convertToPublic(item);
        resolve(item);
      });
     });
  }
}

let persistence = new MyPostgresPersistence();
persistence.configure(ConfigParams.fromTuples(
    "host", "localhost",
    "port", 27017
));

await persitence.open("123");
let item = await persistence.set("123", { name: "ABC" });
item = await persistence.getByName("123", "ABC");
console.log(item);   // Result: { name: "ABC" }