MySqlPersistence

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 self._db or self._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.

MySqlPersistence(table_name: str = None, schema_name: str = None)

• table_name: str - (optional) a table name.
• schema_name: str - (optional) a schema name.

Fields

Instance methods

clear

Clears a component’s state.

clear(context: Optional[IContext])

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

_clear_schema

Clears all auto-created objects

_clear_schema()

close

Closes a component and frees the used resources.

close(context: Optional[IContext])

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

configure

Configures component by passing configuration parameters.

configure(config: ConfigParams)

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

_convert_from_public

Converts object value from public to internal format.

_convert_from_public(value: Any): Any

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

_convert_to_public

Converts object value from internal to public format.

_convert_to_public(value: Any): Any

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

create

Creates a data item.

create(context: Optional[IContext], item: T): Optional[T]

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

_request

Performs a request to the database.

_request(query: str, params: List[str] = None): dict

• query: str - string with sql query to database
• params: List[str] - optional list of query parameters
• returns: dict - result of the query

_create_schema

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

_create_schema(context: Optional[IContext])

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

_define_schema

Defines database schema via auto create objects or convenience methods.

_define_schema()

delete_by_filter

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

delete_by_filter(context: Optional[IContext], filter: Any)

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

_ensure_index

Adds index definition to create it on opening.

_ensure_index(keys: Any, options: Any = None)

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

_ensure_schema

Adds a statement to schema definition.

_ensure_schema(schema_statement: str)

• schema_statement: str - statement to be added to the schema

_generate_columns

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

_generate_columns(values: Any): str

• values: Any - array with column values or a key-value map
• returns: str - generated list of column names

_generate_parameters

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

_generate_parameters(values: Any): str

• values: Any - array with values or a key-value map
• returns: str - generated list of value parameters

_generate_set_parameters

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

_generate_set_parameters(values: Any): str

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

_generate_values

Generates a list of column parameters.

_generate_values(values: Any): List[Any]

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

get_count_by_filter

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

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

get_count_by_filter(context: Optional[IContext], filter: Any): int

• context: IContext - (optional) a context to trace execution through a call chain.
• filter: Any - (optional) JSON object filter
• returns: int - number of filtered items.

get_list_by_filter

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 get_list_by_filter method from a child class that receives FilterParams and converts them into a filter function.

get_list_by_filter(context: Optional[IContext], filter: Any, sort: Any = None, select: Any = None): List[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: List[T] - data list of results by filter.

get_one_random

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

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

get_one_random(context: Optional[IContext], filter: Any): T

• context: IContext - (optional) a context to trace execution through a call chain.
• filter: Any - (optional) a filter function to filter items.
• returns: T - a random item.

get_page_by_filter

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 get_page_by_filter method from the a child class that receives FilterParams and converts them into a filter function.

get_page_by_filter(context: Optional[IContext], filter: Any, paging: PagingParams, sort: Any = None, select: Any = None): 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: DataPage - a data page of result by filter

is_open

Checks if the component is opened.

is_open(): bool

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

open

Opens the component.

open(context: Optional[IContext])

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

_quote_identifier

Adds single quotes to a string.

_quote_identifier(value: str): Optional[str]

• value: str - string where quotes need to be added
• returns: Optional[str] - string with added quotes

_quoted_table_name

Joins schema and database name in dot notation

_quoted_table_name(): Optional[str]

• returns: Optional[str] - string with added quotes

set_references

Sets references to dependent components.

set_references(references: IReferences)

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

unset_references

Unsets (clears) previously set references to dependent components.

unset_references()

Examples

class MyMySqlPersistence(MySqlPersistence):

    def __init__(self):
        super(MyMySqlPersistence, self).__init__('mydata')

    def get_by_name(self, context, name):
        criteria = {'name':name}
        return self._model.find_one(criteria)

    def set(self,context, item):
        criteria = {'name': item['name']}
        options = {'upsert': True, 'new': True}
        return self._model.find_one_and_update(criteria, item, options)

persistence =MyMySqlPersistence()
persistence.configure(ConfigParams.from_tuples(
    "host", "localhost",
    "port", 27017
))

persistence.open('123')
persistence.set('123', {'name':'ABC'})

item = persistence.get_by_name('123', 'ABC')
print(item) # Result: { name: "ABC" }