How do determine the custom field number for epic name

[Quest Henkart]

Hello, I am creating a Jira Connect app that involves me creating an issue via the v2 API. When trying to create an epic, I get the error that the epic name must be set. However it turns out that the epic name field is an arbitrary custom field that is different on every environment.

I can hard code the custom field to get it to work (10011 for me), but I need to be able to do this programmatically so that it works for anyone. Is there a way to use a static key to set the epic name field? If not, how do I get the custom field id for the epic name?

The epic field name is 100% unnecessary for my uses as it will just be a duplicate of the summary field. So if there is a way to skip setting this field that would be optimal. 

There is a frustratingly lack of information about this interaction in the docs

[José León _Sistel_]

You must not use field id hard coded, you must get the field object by name first:

customFieldManager.getCustomFieldObjectByName("custom-field-name");

[Quest Henkart]

Thank you for the response. How would this be done using the REST api. i am creating a Jira epic from a 3rd party app so I do not have access to these methods 

[Daniel_Mitchell]

https://yourserver.atlassian.net/rest/api/2/field

Parse the result, find 'epic name' in there. (Not sure how it works in non-English environments, sorry)

[Sanjeev Deshpande]

Thanks Daniel. This really is a helpful answer and solved lot of trouble for me