PostgresPersistence

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

• table: (optional) PostgreSQL table name
• schema: (optional) PostgreSQL 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 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, schemaName?: string)

• tableName: string - (optional) table name.
• schemaName: string - (optional) a schema name.

Fields

Instance methods

clear

Clears a component’s state.

public clear(context: IContext): Promise<void>

• context: IContext- a context to trace execution through a call chain.

clearSchema

Clears all auto-created objects.

protected clearSchema(): void

close

Closes the component and frees used resources.

public close(context: IContext): Promise<void>

• context: IContext- a context to trace execution through a call chain.

configure

Configures the component.

public configure(config: ConfigParams): void

• config: ConfigParams - configuration parameters to set.

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(context: IContext, item: T): Promise<T>

• context: IContext - (optional) a context to trace execution through a 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(context: IContext): Promise<void>

• context: IContext - (optional) a context to trace execution through a 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(context: IContext, filter: any): Promise<void>

• context: IContext - (optional) a context to trace execution through a 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: "$1,$2,$3".

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: "@1,@2,@3".

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(context: IContext, filter: any): Promise<number>

• context: IContext - (optional) a context to trace execution through a 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(context: IContext, filter: any, sort: any, select: any): Promise<T[]>

• context: IContext - (optional) a context to trace execution through a 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(context: IContext, filter: any): Promise<T>

• context: IContext - (optional) a context to trace execution through a call chain.
• filter: any - (optional) filter for JSON objects
• 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(context: IContext, filter: any, paging: PagingParams, sort: any, select: any): Promise<DataPage>

• context: IContext - (optional) a context 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.

public isOpen(): boolean

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

open

Opens the component.

public open(context: IContext): Promise<void>

• context: IContext - (optional) a context to trace execution through a 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

quotedTableName

Joins schema and database name in dot notation

protected quotedTableName(): string

• 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.

unsetReferences

Unsets (clears) previously set references to dependent components.

public unsetReferences(): void

Examples

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

    protected defineSchema(): void {
        this.clearSchema();
        this.ensureSchema('CREATE TABLE ' + this._tableName + ' (id TEXT PRIMARY KEY, name TEXT, content TEXT)');
        this.ensureIndex(this._tableName + '_key', { name: 1 }, { unique: true });
    }

    public async set(context: IContext, item: MyData): Promise<MyData> {
        if (item == null)
            return null;
        
        let row = this.convertFromPublic(item);
        let columns = this.generateColumns(row);
        let params = this.generateParameters(row);
        let setParams = this.generateSetParameters(row);
        let values = this.generateValues(row);

        let query = "INSERT INTO " + this.quotedTableName() + " (" + columns + ")"
            + " VALUES (" + params + ")"
            + " ON CONFLICT (\"id\") DO UPDATE SET " + setParams + " RETURNING *";

        let newItem = await new Promise<any>((resolve, reject) => {
            this._client.query(query, values, (err, result) => {
                if (err != null) {
                    reject(err);
                    return;
                }

                let item = result && result.rows && result.rows.length == 1
                    ? result.rows[0] : null;
                resolve(item);
            });
        });

        newItem = this.convertToPublic(newItem);
        return newItem;
    }

    public async getOneByName(context: IContext, name: string): Promise<MyData> {
        let query = "SELECT * FROM " + this.quotedTableName() + " WHERE \"name\"=$1";
        let params = [name];

        let item = await new Promise<any>((resolve, reject) => {
            this._client.query(query, params, (err, result) => {
                if (err != null) {
                    reject(err);
                    return;
                }

                let item = result && result.rows ? result.rows[0] || null : null;
                resolve(item);
            });
        });

        item = this.convertToPublic(item);
        return item;
    }
}

let persistence = new MyPostgresPersistence();
persistence.configure(ConfigParams.fromTuples(
    "connection.host", "localhost",
    "connection.port", 5432,
    "credential.username", "postgres",
    "credential.password", "postgres",
    "connection.database", "mytestobjects"
));

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