Introduction:
In my last blog post (Business Central API -1 ) on Creating API in Business Central, we discussed all the commonly used properties of the page, query, and controls like field and data-item.
In today's blog, we will be diving deeply into the validation of the data passed through the API endpoint, how it enters into the source tables and is manipulated to be inserted/modified into single or multiple tables.
Also, I will be demonstrating how APIs are to be used.

Pre-requisites:

Books & References:
  • API V1 from Business Central On-Premise DVD
  • API(V1.0) for Business Central (Click Here)
  • API(Beta) for Business Central (Click Here)

Theory:
Understanding API in Business Central
1. BINDSUBSCRIPTIONS: Use to trigger IntegrationEvent for the Codeunit stated in parameters whenever the function calling BINDSUBSCRIPTION is invoked.

2. Actions through OData API: Actions in API is basically a function called through to API to call some actions passing the current record as parameter

3. Parsing JSON strings to actual records: Parsing  JSON string is used generally where EDM is used. For Eg: While passing payment method on Customer, we pass one or more JSON arrays thus this value is passed as a parameter on the field. To convert JSON array to actual field values on the table, we parse the JSON string.

4. General functions on Validate Trigger: Whenever a data is passed on the field on any page, you can use OnValidate trigger on the field to invoke a code to perform a set of procedures. This can ideally used in creation of No. in a Number Series. Whenever we pass a record, we don't know the next No. in Number Series. Thus NAV/ BC should automatically insert the record with appropriate No.

5. Using Codeunits for achieving the functionality:
There are few Codeunits present in C/AL  which can be used to Install/Uninstall extensions through API. In Business Central Extensions you are not allowed to use such functions but are accessible through C/AL Development Environment.

Demonstration:
How to use APIs in Business Central

1. Viewing List of APIs:

List of Companies:

2. Filtering Records in API:
Text Filtering 


DateTime Filtering

3. Selecting Records in API:






Conclusion:
I think everyone agrees that to write an APIs, you've to be creative while adding or modifying the data. Thus, to sum up, we've seen the key components in  implementation of APIs in Business Central.Also, I have demonstrated how to use APIs. In my next blog, I'll be giving an example which consists of scenarios for API creation and explain the details of all the code used in this blog.