MongoDB module

A set of components used to implement MongoDB persistence.

Packages

The module contains the following packages:

Build - Factory to create MongoDB persistence components.
Connect - Connection component to configure MongoDB connection to database.
Persistence - abstract persistence components to perform basic CRUD operations.

Use

Install the Python package as

pip install pip-services4-mongodb

As an example, lets create persistence for the following data object.

class Dummy(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 pip_services3_commons.data import DataPage, PagingParams, FilterParams


class IMyPersistence:

    def get_page_by_filter(self, correlation_id: str, filter: FilterParams, paging: PagingParams) -> DataPage:
        pass

    def get_one_by_id(self, correlation_id: Optional[str], id: str) -> T:
        pass

    def get_one_by_key(self, correlation_id: Optional[str], key: str) -> T:
        pass

    def create(self, correlation_id: Optional[str], item: T)-> T:
        pass

    def update(self, correlation_id: Optional[str], item: T)-> T:
        pass

    def delete_by_id(self, correlation_id: Optional[str], id: str) -> T:
        pass

To implement mongodb persistence component you shall inherit IdentifiableMongoDbPersistence. 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.

from pip_services3_commons.data import FilterParams
from pip_services3_mongodb.persistence import IdentifiableMongoDbPersistence


class MyMongoDbPersistence(IdentifiableMongoDbPersistence):
    def __init__(self):
        super(MyMongoDbPersistence, self).__init__('myobjects')

    def __composeFilter(self, filterr):
        filterr = filterr or FilterParams()
        id = filterr.get_as_nullable_string("id")
        if id:
            filterr.update({'_id': id})
        temp_ids = filterr.get_as_nullable_string("ids")
        if temp_ids:
            ids = temp_ids.split(",")
            filterr.update({'_id': {'$in': ids}})
        ids = temp_ids.split(",") if temp_ids is not None else None
        if ids:
            filterr.update({'_id': {'$in': ids}})
        key = filterr.get_as_nullable_string("key")

        if key:
            filterr.update({'key': key})

        if len(filterr) > 0:
            return {'$and': filterr}
        else:
            return None

    def get_page_by_filter(self, correlation_id, filter, paging, sort=None, select=None):
        return super().get_page_by_filter(correlation_id, filter, paging, '_id', select)

    def get_one_by_key(self, correlation_id, key):

        filterr = {'key': key}
        item = self._collection.find_one(filterr)
        if item:
            self._logger.trace(correlation_id, "Retrieved from {} with key = {}", self._collection_name, key)
            item = self._convert_to_public(item)
            return item
        else:
            self._logger.trace(correlation_id, "Nothing found from {} with key = {}", self._collection_name, key)

Configuration for your microservice that includes mongodb persistence may look the following way:

...
{{#if MONGODB_ENABLED}}
- descriptor: pip-services:connection:mongodb:con1:1.0
  collection: {{MONGO_COLLECTION}}{{#unless MONGO_COLLECTION}}myobjects{{/unless}}
  connection:
    uri: {{{MONGO_SERVICE_URI}}}
    host: {{{MONGO_SERVICE_HOST}}}{{#unless MONGO_SERVICE_HOST}}localhost{{/unless}}
    port: {{MONGO_SERVICE_PORT}}{{#unless MONGO_SERVICE_PORT}}27017{{/unless}}
    database: {{MONGO_DB}}{{#unless MONGO_DB}}app{{/unless}}
  credential:
    username: {{MONGO_USER}}
    password: {{MONGO_PASS}}
    
- descriptor: myservice:persistence:mongodb:default:1.0
  dependencies:
    connection: pip-services:connection:mongodb:con1:1.0
{{/if}}
...