Compare two form field definitions

When to use this endpoint

Use as CRM1’s compatibility check before merging duplicate tables. All stored field properties matter; form-level names, settings and existing job answers remain outside this field comparison.

Authentication and permissions

The request must authenticate with signed API-key fields or a logged-in CRM session and is scoped to the authenticated tenant.

The handler performs no form, department, owner, or page-permission check unless the page below says otherwise. CRM navigation may impose additional UI-only access rules.

Parameters

Parameter	Type	Required	Description
`form_a / form_b`	Integer-compatible form IDs	Both	Both IDs must integer-convert above zero. Both forms must exist, including when the supplied IDs are identical.

Example request

$comparison = FM_api('Form_areFieldsEqual', ['form_a'=>'1042','form_b'=>'1088']);

Example response

{"ok":1,"is_equal":1}

On a difference, the reply is an error with decoded full fields arrays under form_a and form_b, not {is_equal:0}. Missing records have a separate error.

Errors and unusual responses

Response	Condition
`{"error":"not logged in"}`	No authenticated tenant context is available. Invalid signed credentials can be rejected by the dispatcher before the handler runs.
`{"error":"missing or invalid parameters: form_a, form_b"}`	Either ID converts below 1.
`{"error":"one of the forms does not exist"}`	At least one form row is absent. Database failures return Unable to compare form fields.
`{"error":"fields are not equal","form_a":[...],"form_b":[...]}`	Complete canonical field definitions differ. The actual response contains decoded stored arrays; ellipses here denote their contents.
`{"error":"Form fields are invalid; comparison was not performed."}`	A fields value is not a valid ordered list of named, typed field objects.
`{"error":"Field metadata is invalid; comparison was not performed."}`	A field meta value is malformed or not a JSON object/array.
`{"error":"Unable to compare form fields"}`	Database lookup or another comparison operation failed.

Legacy application errors may be returned with HTTP 200. Check the decoded response for error, not only the HTTP status.

Behaviour and edge cases

Authenticated lookup verifies both forms, including for equal IDs. Archived definitions and every form type are eligible; equality is about fields, not form-level type/name/settings.
Compares all stored field properties, including extras, validation/options and stable IDs inside meta. Different table references or options therefore prevent equality. Field order and ordered option arrays remain significant.
Object property order is canonicalized recursively. Valid JSON in each field’s meta is decoded before canonical comparison, so whitespace/key order inside equivalent metadata objects does not create a false difference. Object/array and scalar types remain significant; a missing meta defaults to an empty array.
Malformed fields or metadata return explicit errors rather than equality. A difference still returns error plus the decoded original fields arrays under form_a/form_b; it does not mutate or normalize stored definitions.
No direct mobile app/m-service caller was found. This check is read-only and does not move job answers, replace parent references or archive a table.

Side effects

Read-only; no history, cache invalidation, file write, URL fetch or report rendering.

See it in Fieldmotion

CRM1

Forms duplicate-table merge (widgetMergeTables) compares each selected table against the first with Form_areFieldsEqual, then performs separate reads, retargeting and archive calls.

CRM2

No direct production caller found. Current Forms editing does not use this legacy table-merge check.

Related endpoints

Form_listFormsWithTable finds parent forms for the merge workflow.
Form_get returns the enclosing form settings, which this comparison does not compare.