MySqlPersistence<T>

Implements: IReferenceable, IUnreferenceable, IConfigurable, IOpenable, ICleanable

Description

The MySqlPersistence 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

Creates a new instance of the persistence component.

public MySqlPersistence(Class documentClass, String tableName, String schemaName)

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

Fields

Instance methods

clear

Clears a component’s state.

public void clear(IContext context)

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

clearSchema

Clears all auto-created objects

protected void clearSchema()

close

Closes a component and frees the used resources.

public void close(IContext context) throws ApplicationException

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

configure

Configures component by passing configuration parameters.

public void configure(ConfigParams config) throws ConfigException

• config:: ConfigParams - configuration parameters to be set.

convertFromPublic

Converts object value from public to internal format.

protected Map<String, Object> convertFromPublic(Object value)

• value: Object - object in public format to convert.
• returns: Map<String, Object> - converted object in internal format.

convertToPublic

Converts object value from internal to public format.

protected T convertToPublic(Map<String, Object> value)

• value: Map<String, Object> - object in internal format to convert.
• returns: T - converted object in public format.

create

Creates a data item.

public T create(IContext context, T item)

• context: IContext - (optional) a context to trace execution through a call chain.
• item: T - item to be created.
• returns: T - created item

createSchema

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

protected void createSchema(IContextt context)

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

defineSchema

Defines database schema via auto create objects or convenience methods.

protected void 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.

protected void deleteByFilter(IContext context, String filter)

• context: IContext - (optional) a context to trace execution through a call chain.
• filter: String - (optional) filter function to filter items.

ensureIndex

Adds index definition to create it on opening.

protected void ensureIndex(String name, Map<String, Object> keys, Map<String, Object> options)

• keys: Map<String, Object> - index keys (fields)
• options: Map<String, Object> - index options

ensureSchema

Adds a statement to schema definition.

protected void ensureSchema(String schemaStatement)

• 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 String generateColumns(Map<String, Object> values)

• values: Map<String, Object> - 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 String generateParameters(Map<String, Object> values)

• values: Map<String, Object> - 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

protected String generateSetParameters(Map<String, Object> values)

• values: Map<String, Object> - key-value map with columns and values
• returns: String - generated list of column sets

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.

protected long getCountByFilter(IContext context, Object filter)

• context: IContext - (optional) a context to trace execution through a call chain.
• filter: Object - (optional) JSON object filter
• returns: long - 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 List getListByFilter(IContext context, String filter, String sort, String select)

• 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
• select: String - (optional) projection parameters (not used yet)
• returns: List - 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.

protected T getOneRandom(context: IContext, String filter)

• context: IContext - (optional) a context to trace execution through a call chain.
• filter: String - (optional) a filter JSON object
• returns: - 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.

protected DataPage getPageByFilter(context: IContext, String filter, paging: PagingParams, String sort, String select)

• 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: DataPage - a data page of result by filter

isOpen

Checks if the component is opened.

public boolean isOpen()

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

open

Opens the component.

public void open(context: IContext)

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

quoteIdentifier

Adds single quotes to a string.

protected String quoteIdentifier(value: 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 String quotedTableName()

• returns: string - string with added quotes

setReferences

Sets references to dependent components.

public void setReferences(references: IReferences)

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

unsetReferences

Unsets (clears) previously set references to dependent components.

public void unsetReferences()

Examples

{@code
public class MyMySqlPersistence extends MySqlPersistence<MyData> {


   public MyMySqlPersistence(Class<MyData> documentClass) {
       super(documentClass, "mydata", null);
   }

   public MyData getByName(IContext context, String name) {
       MyData item;
       var resultMap = new HashMap<String, Object>();

       var query = "SELECT * FROM " + this.quotedTableName() + " WHERE name=" + "'" + name + "'";

       try (var stmt = this._client.createStatement()) {
           var rs = stmt.executeQuery(query);

           if (rs.next())
               for (int columnIndex = 1; columnIndex <= rs.getMetaData().getColumnCount(); columnIndex++)
                   resultMap.put(rs.getMetaData().getColumnName(columnIndex), rs.getObject(columnIndex));
       } catch (SQLException ex) {
           throw new RuntimeException(ex);
       }

       item = this.convertToPublic(resultMap);

       return item;
   }

   public MyData set(IContext context, MyData item) {
       if (item == null)
           return null;

       var row = this.convertFromPublic(item);
       var columns = this.generateColumns(row);
       var params = this.generateParameters(row);
       var setParams = this.generateSetParameters(row);

       var query = "INSERT INTO " + this.quotedTableName() + " (" + columns + ") VALUES (" + params + ")";
       query += " ON DUPLICATE KEY UPDATE " + setParams + ";";

       MyData newItem;
       var resultMap = new HashMap<String, Object>();

       try (var stmt = this._client.createStatement()) {
           stmt.execute(query);

           query = "SELECT * FROM " + this.quotedTableName() + " WHERE id=" + "'" + item.getId().toString() + "'";

           var rs = stmt.executeQuery(query);

           // fetch results
           if (rs.next())
               for (int columnIndex = 1; columnIndex <= rs.getMetaData().getColumnCount(); columnIndex++)
                   resultMap.put(rs.getMetaData().getColumnName(columnIndex), rs.getObject(columnIndex));
       } catch (SQLException ex) {
           throw new RuntimeException(ex);
       }

       newItem = this.convertToPublic(resultMap);
       return newItem;
   }
 }
 ...
 var persistence = new MyMySqlPersistence(MyData.class);
 persistence.configure(ConfigParams.fromTuples(
       "host", "localhost",
       "port", 3306
 ));

 persistence.open(null);

 persistence.set("123", new MyData("1", "ABC", "content"));
 var item = persistence.getByName("123", "ABC");
 System.out.println(item.getName());
 }