Some times, you want to hide a field in frontend or backend item edit form or in both.

-- Of course when the field is hidden in the form it will maintain it's existing value.

Method 1:
(For end-user / web-designers:)

In v1.5.6 + there is a new field property in field configuration, that allows to select to hide the field in frontend / backend or both item forms

Also new in v1.5.6+ there is also a new parameter to FORCE a default value in a text field (and a few other fields) without ever needing to save any field value in the database.

-- The above can be useful if you want to add a field to all your (thousands) items without need to re-edit them.

-- This becomes really useful for triggering specific plugins inside the text field, that donot require per item value !!!

(For Developers:)

To define a field as being ALWAYS hidden in the edit form for e.g. field myfield:

Edit the file myfield.xml

To hide in backend, add a hidden parameter called backend_hidden:

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<param name="backend_hidden" default="1" type="hidden" label="Hide in backend form" description="" />

To hide in frontend, add a hidden parameter called frontend_hidden:

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<param name="frontend_hidden" default="1" type="hidden" value="1" label="Hide in frontent form" description="" />

NOTE: to hide in both frontend and backend, add both parameter.

NOTE: for J1.6/J1.7/J2.5 use field instead of param