---
title: Fields and custom fields
description: Read an entity's fields and dropdown options from the Fields endpoint, create custom fields, and update dropdown options without deleting the ones you leave out.
canonical: https://developers.coevera.com/concepts/fields-and-custom-fields/
section: concepts
verification: schema
lastVerified: 2026-10-15
publisher: Coevera
---

# Fields and custom fields

**Answer:** GET /entities/Fields with filter[entity_name]=Account lists an entity's fields with their api_name, type and options. Create a custom field with POST /entities/Fields and change it with PATCH /entities/Fields/{id}. A data_set you send replaces the whole option list: an option you leave out is deleted. Key integrations on api_name, never on the label.

Fields are records too. The `Fields` entity describes every field of every entity in your space,
the standard ones and your custom ones, so an integration can find a field's API name and its
dropdown options at run time instead of hard-coding them.

## Find a field's API name

List an entity's fields with [`GET /entities/Fields`](/reference/rest/fields/#list) and these parameters:

| Parameter             | Value                                                       | Why                                                                                                                                                                                                                                 |
| --------------------- | ----------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `filter[entity_name]` | `Account`                                                   | The singular entity name, such as `Account`, `Opportunity`, `OpptyProductRelation` or `Quote`. The shared parents `LeadOppty` and `Activity` have no fields of their own: ask for `Lead` or `Opportunity`, `Task` or `Appointment`. |
| `expand`              | `data_set`                                                  | Returns a dropdown's options with their `id` and `option_name`                                                                                                                                                                      |
| `load-only`           | `id,name,api_name,type_id,data_set.id,data_set.option_name` | Keeps the response small                                                                                                                                                                                                            |
| `first`               | `100`                                                       | An entity can have more fields than the default page of 30                                                                                                                                                                          |

Each field has a `name`, the label the app shows, and an `api_name`, the key in the entity's
records. Custom fields have API names that start with `cf_`; a dropdown's ends with `_id`, because
the record stores the option's ID.

The API name is made from the field's name when the field is created, and then it stays:

- Renaming a field changes `name`, not `api_name`.
- A field deleted and created again under the same name gets a new API name with a number added:
  `cf_customer_tier` becomes `cf_customer_tier1`. An integration keyed on the old name stops
  finding the field.

So store `api_name`, never the label, and do not recreate a field an integration uses.

## Create a custom field

[`POST /entities/Fields`](/reference/rest/fields/#create) creates a field. The body names the entity
in `entity_name`, the label in `name` and the type in `type_id`:

| `type_id`                                          | Field                                                                  |
| -------------------------------------------------- | ---------------------------------------------------------------------- |
| `input`, `text_area`                               | Single-line and long text                                              |
| `integer`, `float`, `currency`, `currency_foreign` | Numbers and money                                                      |
| `date`, `datetime`                                 | A date, a date and time                                                |
| `checkbox`                                         | True or false                                                          |
| `dropdown`, `radio`, `multiselect_checkbox`        | Options from `data_set`: an array of `{ "option_name", "calc_value" }` |
| `email`, `phone`, `url`                            | Validated text                                                         |
| `sequence`                                         | An auto-number                                                         |

Give every option a `calc_value`, the number it counts as in calculated fields.

## Update dropdown options

Update a field with [`PATCH /entities/Fields/{id}`](/reference/rest/fields/#update). A PATCH sent to `/entities/{id}` without
`Fields` in the path answers HTTP 405.

> **data_set replaces every option:** The `data_set` you send becomes the field's whole option list. Send every option you keep, each
> existing one with its `id`, and new ones without an `id`. An option you leave out is deleted.

For example, a dropdown with the options Gold, Silver and Bronze, updated with a `data_set` of
Gold (by its `id`) and a new Platinum, reads back with `expand=data_set` as Gold and Platinum:
Silver and Bronze are deleted.

## Limits

| Limit         | Details                                                                         |
| ------------- | ------------------------------------------------------------------------------- |
| `entity_name` | Concrete entities only; `LeadOppty` and `Activity` have no fields               |
| `data_set`    | Replaces the whole list on every write                                          |
| API names     | Fixed at creation; a re-created field gets a new one                            |
| GraphQL       | This page covers REST; the public GraphQL schema has its own `field` repository |