---
title: "form_block"
description: "Ordered blocks within a form."
---

Ordered blocks within a form.

## Source

| Model | Leg | Role |
|---|---|---|
| `form_block` | openEHR | defines this table |

A form is a sequence of blocks. Narrative blocks hold their text in `content`; every other block type is backed by an entry row that points at it, which is what the check constraint enforces — `content` is present exactly when `block_type` is `text`.

Entry tables reference `(form_id, id)` rather than `id` alone, so an entry cannot be attached to a block belonging to a different form.

## Columns

| Column | Type | Null | Description | Source |
|---|---|---|---|---|
| `id` | `uuid primary key` | no | Primary key. | — |
| `form_id` | `uuid` | no | The form this block belongs to. | — |
| `position` | `integer` | no | Order of the block within the form, from zero. | — |
| `block_type` | `text` | no | What kind of block this is; `text` blocks hold narrative, the rest are backed by an entry. | — |
| `content` | `text` | yes | Narrative text, present only for `text` blocks. | — |
| `content_metadata` | `json` | yes | Free-form metadata for the block's renderer. | — |

## Constraints

```sql
check ((block_type = 'text' and content is not null) or (block_type <> 'text' and content is null))
```

## Unique

- `form_id, position`
- `form_id, id`

## References

| Columns | Target | On delete |
|---|---|---|
| `form_id` | [`form`](/docs/tables/form) | cascade |

## Referenced by

155 tables reference `form_block`, via `form_id, form_block_id`. The first 15 alphabetically:

- [`absence`](/docs/tables/absence) via `form_id, form_block_id`
- [`acvpu`](/docs/tables/acvpu) via `form_id, form_block_id`
- [`advance_care_directive`](/docs/tables/advance_care_directive) via `form_id, form_block_id`
- [`advance_intervention_decisions`](/docs/tables/advance_intervention_decisions) via `form_id, form_block_id`
- [`adverse_reaction_monitoring`](/docs/tables/adverse_reaction_monitoring) via `form_id, form_block_id`
- [`adverse_reaction_risk`](/docs/tables/adverse_reaction_risk) via `form_id, form_block_id`
- [`adverse_reaction_screening`](/docs/tables/adverse_reaction_screening) via `form_id, form_block_id`
- [`age_assertion`](/docs/tables/age_assertion) via `form_id, form_block_id`
- [`alcohol_consumption_summary`](/docs/tables/alcohol_consumption_summary) via `form_id, form_block_id`
- [`apgar`](/docs/tables/apgar) via `form_id, form_block_id`
- [`art_cycle_summary`](/docs/tables/art_cycle_summary) via `form_id, form_block_id`
- [`asa_status`](/docs/tables/asa_status) via `form_id, form_block_id`
- [`berg_balance_scale`](/docs/tables/berg_balance_scale) via `form_id, form_block_id`
- [`blood_pressure`](/docs/tables/blood_pressure) via `form_id, form_block_id`
- [`body_mass_index`](/docs/tables/body_mass_index) via `form_id, form_block_id`

## Definition

```sql
create table form_block (
    id uuid primary key default uuid_generate_v4(),
    form_id uuid not null references form (id) on delete cascade,
    position integer not null check (position >= 0),
    block_type text not null,
    content text,
    content_metadata json,
    check (
        (block_type = 'text' and content is not null)
        or
        (block_type <> 'text' and content is null)
    ),
    unique (form_id, position),
    unique (form_id, id)
);
```