A set of components to implement SQLServer persistence.
Packages
The module contains the following packages:
- Build - a standard factory for constructing components
- Connect - instruments for configuring connections to the database.
- Persistence - abstract classes for working with the database that can be used for connecting to collections and performing basic CRUD operations
Use
Install the Python package as
pip install pip-services4-sqlserver
As an example, lets create persistence for the following data object.
class MyObject(IStringIdentifiable):
def __init__(self, id: str = None, key: str = None, content: str = None):
self.id = id
self.key = key
self.content = content
The persistence component shall implement the following interface with a basic set of CRUD operations.
from abc import ABC
from typing import Union, List
from pip_services3_commons.data import IIdentifiable, PagingParams, FilterParams, DataPage
class IMyPersistence(ABC):
def get_page_by_filter(self, correlation_id: Optional[str], filter: Any,
paging: Any) -> DataPage:
raise NotImplemented()
def get_one_by_id(self, correlation_id: Optional[str], id: str) -> MyObject:
raise NotImplemented()
def get_one_by_key(self, correlation_id: Optional[str], key: List[str]) -> MyObject:
raise NotImplemented()
def create(self, correlation_id: Optional[str], item: MyObject) -> MyObject:
raise NotImplemented()
def update(self, correlation_id: Optional[str], item: MyObject) -> MyObject:
raise NotImplemented()
def delete_by_id(self, correlation_id: Optional[str], id: str):
raise NotImplemented()
To implement sql server persistence component you shall inherit IdentifiableSqlServerPersistence.
Most CRUD operations will come from the base class. You only need to override get_page_by_filter method with a custom filter function.
And implement a get_one_by_key custom persistence method that doesn’t exist in the base class.
class MySqlServerPersistence(IdentifiableSqlServerPersistence):
def __init__(self):
super(MySqlServerPersistence, self).__init__('myobjects')
self._ensure_schema("CREATE TABLE [myobjects] ([id] VARCHAR(32) PRIMARY KEY, [key] VARCHAR(50), [value] NVARCHAR(255)")
self._ensure_index("myobjects_key", { '[key]': 1 }, { 'unique': True })
def __compose_filter(self, filter):
filter = filter or FilterParams()
criteria = []
id = filter.get_as_nullable_string('id')
if id is not None:
criteria.append("[id]='" + id + "'")
temp_ids = filter.get_as_nullable_string('ids')
if temp_ids is not None:
ids = temp_ids.split(',')
criteria.append("[id] IN ('" + "','".join(ids) + "')")
key = filter.get_as_nullable_string('key')
if key is not None:
criteria.append("[key]='" + key + "'")
return " AND ".join(criteria) if len(criteria) > 0 else None
def get_page_by_filter(self, correlation_id, filter, paging, sort, select):
return super().get_page_by_filter(correlation_id, self.__compose_filter(filter), paging, 'id', None)
def get_one_by_key(self, correlation_id, key):
query = "SELECT * FROM " + self._quoted_table_name() + " WHERE [key]=?"
params = [key]
result = self._request(query, params)
item = result[0] or None if result and result[0] else None
if item is None:
self._logger.trace(correlation_id, "Nothing found from %s with key = %s", self._table_name, key)
else:
self._logger.trace(correlation_id, "Retrieved from %s with key = %s", self._table_name, key)
item = self._convert_to_public(item)
return item
Alternatively you can store data in non-relational format using IdentificableJsonSqlServerPersistence.
It stores data in tables with two columns - id with unique object id and data with object data serialized as JSON.
To access data fields you shall use JSON_VALUE([data],'$.field') expression.
from pip_services3_sqlserver.persistence.IdentifiableJsonSqlServerPersistence import IdentifiableJsonSqlServerPersistence
class MySqlServerPersistence(IdentifiableJsonSqlServerPersistence):
def __init__(self):
super(MySqlServerPersistence, self).__init__('myobjects')
self._ensure_table()
self._auto_create_object("ALTER TABLE [myobjects] ADD [data_key] AS JSON_VALUE([data],'$.key')")
self._ensure_index("myobjects_key", { 'data_key': 1 }, { 'unique': True })
def __compose_filter(self, filter):
filter = filter or FilterParams()
criteria = []
id = filter.get_as_nullable_string('id')
if id is not None:
criteria.append("JSON_VALUE([data],'$.id')='" + id + "'")
temp_ids = filter.get_as_nullable_string('ids')
if temp_ids is not None:
ids = temp_ids.split(',')
criteria.append("JSON_VALUE([data],'$.id') IN ('" + "','".join(ids) + "')")
key = filter.get_as_nullable_string('key')
if key is not None:
criteria.append("JSON_VALUE([data],'$.key')='" + key + "'")
return " AND ".join(criteria) if len(criteria) > 0 else None
def get_page_by_filter(self, correlation_id, filter, paging, sort, select):
return super().get_page_by_filter(correlation_id, self.__compose_filter(filter), paging, 'id', None)
def get_one_by_key(self, correlation_id, key):
query = "SELECT * FROM " + self._quoted_table_name() + " WHERE JSON_VALUE([data],'$.key')=?"
params = [key]
result = self._request(query, params)
item = result[0] or None if result and result[0] else None
if item is None:
self._logger.trace(correlation_id, "Nothing found from %s with key = %s", self._table_name, key)
else:
self._logger.trace(correlation_id, "Retrieved from %s with key = %s", self._table_name, key)
item = self._convert_to_public(item)
return item
Configuration for your microservice that includes sqlserver persistence may look the following way.
...
{{#if SQLSERVER_ENABLED}}
- descriptor: pip-services:connection:sqlserver:con1:1.0
table: {{SQLSERVER_TABLE}}{{#unless SQLSERVER_TABLE}}myobjects{{/unless}}
connection:
uri: {{{SQLSERVER_SERVICE_URI}}}
host: {{{SQLSERVER_SERVICE_HOST}}}{{#unless SQLSERVER_SERVICE_HOST}}localhost{{/unless}}
port: {{SQLSERVER_SERVICE_PORT}}{{#unless SQLSERVER_SERVICE_PORT}}1433{{/unless}}
database: {{SQLSERVER_DB}}{{#unless SQLSERVER_DB}}app{{/unless}}
credential:
username: {{SQLSERVER_USER}}
password: {{SQLSERVER_PASS}}
- descriptor: myservice:persistence:sqlserver:default:1.0
dependencies:
connection: pip-services:connection:sqlserver:con1:1.0
{{/if}}
...