How to fill custom field value while creating a issue through REST API

[Anshul Mittal]

"customfield_123": {
  "required": true,
  "schema": {
    "type": "option",
    "custom": "com.atlassian.jira.plugin.system.customfieldtypes:select",
    "customId": 123
  },
  "name": "Field_123",
  "key": "customfield_123",
  "hasDefaultValue": false,
  "operations": [
    "set"
  ],
  "allowedValues": [
    {
      "self": "https://xyz.atlassian.net/rest/api/2/customFieldOption/1",
      "value": "abc",
      "id": "1"
    },
    {
      "self": "https://xyz.atlassian.net/rest/api/2/customFieldOption/2",
      "value": "pqr",
      "id": "2"
    }
  ]
}

I want to fill above field while creating issue using REST API in spring.

IssueInputBuilder issueBuilder = new IssueInputBuilder(projectKey, issueType, issueSummary);

issueBuilder.setFieldValue("customfield_123", 1L);

issueBuilder.setFieldValue("customfield_123", "1");

issueBuilder.setFieldValue("customfield_123", "abc");

I have used above variations and all giving the same error below.

Caused by: RestClientException{statusCode=Optional.of(400), errorCollections=[ErrorCollection{status=400, errors={customfield_123=Specify a valid 'id' or 'name' for Field_123}, errorMessages=[]}]}

What should be approach here? 

[Bill Sheboy]

Hi @Anshul Mittal -- Welcome to the Atlassian Community!

First thing, you might also want to look in the developer community for questions like this one: https://community.developer.atlassian.com/

Back to your question...and I have not tried this to verify...

That second parameter to setFieldValue() can be a ComplexIssueInputFieldValue, and so you would need to compose it as needed.  Your custom field appears to be a single select field and so you would need to provide either the id or name attribute for selection.

Kind regards,
Bill