fastiot_core_services.object_storage package¶
FastIoT Service to save “Object” into mongodb,
see fastiot.db.mongodb_helper_fn.get_mongodb_client_from_env()
This Service is intended for saving “Object” inheriting the fastiot.core.data_models.FastIoTData,
and requesting of historical object data. This Service is also designed to save one data type, for demanding saving
multiple data types, you can instance multiple Services, using config file.
Your Object will be saved in Dictionary in such format, ‘yyy’ stands for the unpacked Attributes of Object:
{'_id': 'xxx', '_subject': 'xxx', '_timestamp': 'xxx', 'yyy': 'xxx', 'yyy': 'xxx}
In Order to use this Service, you must set a config file named ObjectStorageService.yaml or
ObjectStorageService_1.yaml in my_deployment/config_dir, for reading ObjectStorageService_1.yaml
FASTIOT_SERVICE_ID must be set.
search_index:
- "_subject"
- "_timestamp"
collection: 'thing'
subject_name: 'thing.*'
“_subject” and “_timestamp” is the basic index for MongoDB, collection is the Mongodb Collection, which you want to
store your data in, subject_name is the subject, where you send your data.
or the subject can be your own Data Model, which inherits fastiot.core.data_models.FastIoTData, e.g.:
class MyDataType(FastIoTData)
You can assign the subject like following ‘MyDataType’ or ‘my_data_type’, both will return you a right subject name format: ‘v1.my_data_type’. CAUTION!: Thing will be instanced with different names. So by subscribing thing please always with a *. For understanding you can reference this https://docs.nats.io/nats-concepts/subjects.
For quick query data in mongodb, search_index must be set. Through collection, the collection will be defined, where you save your data. Furthermore, the subject must be set, it indicates, which topic the nats client function subscripts.
The other functionality for Object Storage Service is, you can make a request of the historical data,
which are saved in Mongodb.
To request the historical data, you need to instantiate fastiot.msg.hist.HistObjectReq,
with subject_name ‘reply_object’.
The code will look like:
hist_req_msg = HistObjectReq(dt_start=datetime(), dt_end=datetime(), limit=10, subject_name='my_data_type')
subject = hist_req_msg.get_reply_subject(name='my_data_type')
CAUTION! This subject_name should be the same as, which you have defined in ObjectStorageService.yaml.
This request will reply to you a List of Dictionary.
Then you can convert it to your own data type using fastiot.util.object_helper.parse_object_list().