Publishing APIs That Support Queries of Null Values- FineDataLink Help Document

Last update: July 04, 2025

Note:

This document applies to FineDataLink of V4.2.6.2 and later versions.

Application Scenario

You want to publish an API that enables fetching NULL data in the published API and querying other data in the meantime.

FineDataLink supports passing a NULL value through a parameter in an API.

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Procedure

This document uses the SORDER table as an example to illustrate how to publish the table data as an API that enables fetching data where the value of SHIPPED_DATE is NULL and querying other data in the meantime.

Creating an API

Click Data Service, choose New > API Service, enter the name of the API service, and click OK, as shown in the following figure.

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Configuring API Information

Service Content (Data Query)

The following figure shows the setting page.

SELECT * FROM `demotest`.`SORDER` where IF ('$Shipped_Date'='NULL', SHIPPED_DATE IS NULL,SHIPPED_DATE='$Shipped_Date')

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The following table describes the setting items.

For details about each setting item, see Overview of API Release.

Setting Item	Description
SQL Statement	Enter the statement. This example uses MySQL syntax. Adjust the statements accordingly if you use other databases.
Pagination Query	Disable Pagination Query. The API to be generated will return data without pagination after being called.
Custom Parameter	Disable Mandatory in Custom Parameter, which means that the parameter value can be empty, and the default value is NULL. After publishing the API, you can perform data filtering with the parameter set in the SQL statement during data fetching through the API.

Setting Item

Description

SQL Statement

Enter the statement. This example uses MySQL syntax. Adjust the statements accordingly if you use other databases.

Pagination Query

Disable Pagination Query. The API to be generated will return data without pagination after being called.

Custom Parameter

Disable Mandatory in Custom Parameter, which means that the parameter value can be empty, and the default value is NULL.

After publishing the API, you can perform data filtering with the parameter set in the SQL statement during data fetching through the API.

API Configuration

1. Select POST as Request Method and set the path to Doc_490. Custom path is supported.

Add an App. If no App has been created, you can skip this step and bind the API to an App in App List after completing the API creation. For details, see Binding an API to an Application. The binding step is mandatory, otherwise the API cannot be called later.

Set Request Body Format to application/json, as shown in the following figure.

For details about each setting item, see Overview of API Release.

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2. Click Test Call in the lower right corner to debug the API. The parameter value of area is NULL. Data where the value of Shipped_Date is NULL is returned, as shown in the following figure.

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3. Click Save and Activate.

Subsequent Operations

If you do not bind the API to a specified App when publishing the API, you can still manage the published API by binding it to an App in App List to ensure that the API can be called.

For details about using published APIs, see Using APIs Released in Data Service (POST application/json Request).

You can view the data where the parameter value is NULL, as shown in the following figure.

For details about managing published APIs, see Data Service O&M.

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Publishing APIs That Support Queries of Null Values