If you have SAP HANA, you can quickly build OData endpoints to back the data needed for your application.
Given that, this post shows how you can use Python 3 to get data from a SAP Hana OData endpoint.
A sample RFID labelling use case
Through SAP HANA XS Advanced, I was able to
expose my database table as an OData endpoint.
Table definition:
SampleProject.data::tag.TagType
COLUMN TABLE "SAMPLE_DB"."SampleProject.data::tag.TagType"(
"id" NVARCHAR(20) NOT NULL,
"tag_id" NVARCHAR(20),
"label" NVARCHAR(10),
PRIMARY KEY (
"id"
)
);
Service definition:
SampleProject/service/dataservice.xsodata
service {
"SampleProject.data::tag.TagType" as "TagType";
}
Given the table definition and service definitions, suppose that my OData service is available at
https://sampleusecaseserver.jp1.hana.ondemand.com/SampleProject/service/dataservice.xsodata/TagType that enables me to perform basic CRUD on the TagType table. In addition to that, we can also use a user, with
my_project_user and
ABcD1234, as the credentials that has privileges to perform CRUD on the table.
After figuring out
how to read RFID tags from my SparkFun RFID reader with Python 3, I was able to populate the TagType table with some tag ids from my RFID cards:
id tag_id label
1577437534275 041A49B920CE can
1577437536208 041A4A6F5368 can
1577437538381 041A49AA6499 can
1577437540602 041A49A93CC2 can
1577437542248 041A49927EBB can
1577437544069 041A49A2D520 can
1577437545970 041A498FD40C can
1577437548111 041A4979341A can
1577437549613 041A49B8907F can
1577437551626 041A49721F3A can
1577437613746 041A498D4F95 paper
1577437616957 041A49A5B446 paper
1577437618826 041A497AF1DC paper
1577437620584 041A49A5DA28 paper
1577437622997 041A4993CD09 paper
1577437625153 041A49B27491 paper
1577437626895 041A49730226 paper
1577437628717 041A49C20297 paper
1577437630187 041A4994EB28 paper
1577437632503 041A49B58664 paper
1577437668285 041A497788A8 plastic
1577437670458 041A49B851BE plastic
1577437672263 041A49A18076 plastic
1577437674324 041A49942BE8 plastic
1577437676305 041A4985EA38 plastic
1577437677919 041A49714066 plastic
1577437679725 041A49999B55 plastic
1577437685061 041A499317D3 plastic
1577437686851 041A498C914A plastic
1577437689088 041A4974E4C7 plastic
1577437721370 041A49777F5F general
1577437723543 041A497E0821 general
1577437725748 041A496E83BA general
1577437727729 041A49A54FBD general
1577437729790 041A49874494 general
1577437732139 041A49A558AA general
1577437734328 041A49869948 general
1577437736357 041A49B3AC48 general
1577437738466 041A4971AA8C general
1577437741150 041A4969EED0 general
Writing the Python 3 codes to get data from a SAP HANA OData endpoint with column matching a particular value
Now that we have a clear picture of what kind of data the table contains, we can then look at some Python 3 codes to get data from a SAP HANA OData endpoint with column matching a particular value.
Typically in order to interact with SAP HANA OData endpoint, we will
construct a HTTP request to the endpoint with HTTP Basic Authentication. Luckily, we can
use requests library to send an HTTP request to a HTTP Basic Authentication endpoint in Python 3 easily.
Since it is easier to deal with JSON data, we will also want to include the
"Accept: application/json" HTTP header to tell our OData endpoint to return JSON data.
In order to find data with column matching a particular value, we will need to
use Filter Expressions in OData URIs.
When there is a record matching our query, we should expect something like the following in the HTTP response:
{
d: {
results: [
{
__metadata: {
type: "SampleProject.service.dataservice.TagTypeType",
uri: "https://sampleusecaseserver.jp1.hana.ondemand.com:443/SampleProject/service/dataservice.xsodata/TagType('1577437534275')"
},
id: "1577437534275",
tag_id: "041A49B920CE",
label: "can"
}
]
}
}
Given all these points, the following Python 3 codes define a function that will return us the label for a particular tag id:
TAG_TYPE_ENDPOINT='https://sampleusecaseserver.jp1.hana.ondemand.com/SampleProject/service/dataservice.xsodata/TagType'
USERNAME='my_project_user'
PASSWORD='ABcD1234'
REQUEST_HEADERS = {
'Accept': 'application/json'
}
def get_tag_type(tag_id=''):
url = "{}?$filter=tag_id eq '{}'".format(TAG_TYPE_ENDPOINT, tag_id)
response = requests.get(url=url
,auth=(USERNAME,PASSWORD)
,headers=REQUEST_HEADERS
)
if response.status_code == 200:
tag_type_d = response.json().get('d', {})
tag_type_results = tag_type_d.get('results', {})
if len(tag_type_results):
tag_type = tag_type_results[0]
return tag_type.get('label', 'unknown')
return 'unknown'
