Field types

A collection's schema is { fields: [ … ] }. Each field has a name (the key stored in entry data), a type, and optional properties. All field definitions share a common base:

{
  "name": "string", // required — key in entry.data (1–100 chars)
  "type": "…", // required — one of the types below
  "label": "Display label", // optional — display label (max 200 chars)
  "help": "Helper text", // optional — helper text under the field (max 500 chars)
  "required": true
}

Type-specific options are: min / max (text length, number range, or group item count), pattern (regex, for text), options (for select/multiselect), relationCollectionId + multiple (for relation), and fields (for group).

Text family

text, textarea, url, email, date, richtext store a string. text supports a pattern regex constraint:

{ "name": "phone", "type": "text", "pattern": "^[+0-9 ]+$" }

Number & boolean

{ "name": "price", "type": "number", "min": 0, "max": 100000 }

boolean accepts true/false, or a string/number that coerces.

Select types

select stores one value; multiselect stores an array — both constrained to the owner-defined options list once provided:

{
  "name": "role",
  "type": "select",
  "options": ["Engineer", "Designer", "Sales"]
}

tags is deliberately different: free-form values the publisher types in, so it has no options.

Images & files

image and file fields store a FileRef object, not a string:

{
  "__file": true,
  "mediaId": "media_…",
  "name": "ada.jpg",
  "size": 204123,
  "type": "image/jpeg",
  "url": "https://cdn.vlozi.app/…/ada.jpg"
}

The value is produced by the upload endpoint before the entry is saved. When required, the field must be present and non-empty.

Relations

A relation field links an entry to the entries of another collection (self-reference allowed). It stores an entry id (or an array of ids when multiple is true):

{
  "name": "featuredProduct",
  "type": "relation",
  "relationCollectionId": "col_products",
  "multiple": false
}

At save time the service verifies each referenced entry exists and belongs to the declared target collection — a row from the wrong collection is a 422. The target does not need to be published yet (you can wire a relation while still drafting the target).

At public read time, set ?populate=true to resolve each relation into the referenced entry's public shape: { id, label, data, publishedAt }. See Embed & relations for the exact shape and rules.

Groups

A group field holds a repeating list of sub-fields — useful for complex, nested content:

{
  "name": "awards",
  "type": "group",
  "fields": [
    { "name": "year", "type": "number" },
    { "name": "title", "type": "text" }
  ]
}

• Groups can nest (a sub-field can itself be a group), up to 3 levels deep.
• A group field can have at most 30 sub-fields defined in its schema.
• Each level may cap its item count with min / max.
• There is a global safety cap of 1000 group items total across every nested level in one entry — beyond that, excess items are silently dropped. Per-level max (default 200) also applies.
• A group needs at least one sub-field.