logseq/libs/development-notes/db_properties_guide.md

Logseq DB Properties (Developer Guide)

This note explains how properties work in Logseq when using a DB graph (database mode), how that differs from a file graph (Markdown/Org), and how to use the plugin SDK APIs defined in libs/src/LSPlugin.ts.

Scope: This is written for plugin developers. It focuses on logseq.Editor.* property APIs and tag/class modeling.

---

1) Two worlds: File graph vs DB graph

File graph (Markdown / Org)

• “Properties” are primarily text syntax stored in the file:
  • Markdown frontmatter (---)
  • Org property drawers (:PROPERTIES:)
  • Inline props (key:: value)
• When you update a property, you’re often ultimately editing text.
• SDK calls like Editor.insertBlock/updateBlock have opts.properties, but note this warning in the typings:
  • IBatchBlock.properties is not supported for DB graph.

DB graph (Database mode)

DB mode treats properties as first-class DB entities.

Think of it as a 2-layer model:

1) Property definitions (schema)

• A property key (e.g. rating, authors, zotero_key) exists as an entity.
• It may have a schema: type, cardinality, visibility.

2) Property values (data)

• Blocks/pages can store values for property keys.
• Persisted structurally in the DB (not by emitting key:: value text).

In DB graphs, prefer the dedicated APIs:

• Property schema: Editor.getProperty / upsertProperty / removeProperty
• Values on blocks: Editor.upsertBlockProperty / removeBlockProperty / getBlockProperties

---

2) Important types (from LSPlugin.ts)

PropertySchema

export type PropertySchema = {
  type: 'default' | 'number' | 'node' | 'date' | 'checkbox' | 'url' | string,
  cardinality: 'many' | 'one',
  hide: boolean
  public: boolean
}

Practical meaning:

• type
  • Controls editor/UI behavior and (in DB graphs) how values are interpreted.
  • Common: default, number, date, checkbox, url, node.
• cardinality
  • 'one': a single value
  • 'many': multiple values (typically passed as an array)
• hide
  • Hide in UI property panels.
• public
  • Expose property in UI (and typically configure discoverability).

Entities you’ll see

• BlockEntity: blocks, but also used for some “special blocks” such as property entities.
• PageEntity: pages, tags (classes), property pages (type: 'property'), etc.
• BlockIdentity: a block uuid string OR { uuid }.

---

3) DB-only vs graph-agnostic checks

Before doing DB-only work, check graph type:

const isDbGraph = await logseq.App.checkCurrentIsDbGraph()
if (!isDbGraph) {
  await logseq.UI.showMsg('This feature requires a DB graph.', 'warning')
  return
}

// Also check app-level capability:
const { supportDb } = await logseq.App.getInfo()

---

4) Property schema APIs (DB only)

Get a property definition

const propEntity = await logseq.Editor.getProperty('zotero_key')
// -> BlockEntity | null

Create or update a property definition (idempotent)

Use upsertProperty to ensure the property exists and has the schema you expect.

await logseq.Editor.upsertProperty(
  'zotero_key',
  {
    type: 'default',
    cardinality: 'one',
    hide: false,
    public: true,
  },
  { name: 'Zotero Key' }
)

Notes:

• key is your stable identifier (recommend snake_case).
• opts.name can be used as a display name for users.

Remove a property definition

await logseq.Editor.removeProperty('zotero_key')

---

5) Block/page property value APIs

Set (upsert) a property value on a block

const block = await logseq.Editor.getCurrentBlock()
if (!block) return

await logseq.Editor.upsertBlockProperty(block.uuid, 'zotero_key', 'ABCD1234')

Set multi-value properties (cardinality: 'many')

For many, pass an array. Use { reset: true } when you want to overwrite vs merge.

await logseq.Editor.upsertBlockProperty(
  block.uuid,
  'authors',
  ['Ada Lovelace', 'Alan Turing'],
  { reset: true }
)

Remove a value

await logseq.Editor.removeBlockProperty(block.uuid, 'zotero_key')

Read properties

const props = await logseq.Editor.getBlockProperties(block.uuid)
// -> Record<string, any> | null

const pageProps = await logseq.Editor.getPageProperties('My Page')

Read a single property (returns a BlockEntity | null)

getBlockProperty is useful when you want the DB entity wrapper for a key.

const v = await logseq.Editor.getBlockProperty(block.uuid, 'zotero_key')

---

6) Tags as “classes” + attaching properties (DB modeling)

In DB graphs, tags can behave like classes.

Relevant APIs:

• Editor.createTag(tagName, opts)
• Editor.addTagProperty(tagId, propertyIdOrName) / removeTagProperty
• Editor.addTagExtends(tagId, parentTagIdOrName) / removeTagExtends
• Editor.addBlockTag(blockId, tagId) / removeBlockTag

Create a tag with tagProperties

This is the most developer-friendly way to ship a “schema bundle”:

const tag = await logseq.Editor.createTag('ZoteroItem', {
  tagProperties: [
    {
      name: 'zotero_key',
      schema: { type: 'default', cardinality: 'one', public: true, hide: false },
    },
    {
      name: 'authors',
      schema: { type: 'node', cardinality: 'many', public: true, hide: false },
    },
    {
      name: 'published_at',
      schema: { type: 'date', cardinality: 'one', public: true, hide: false },
    },
  ],
})

if (tag) {
  const block = await logseq.Editor.getCurrentBlock()
  if (block) await logseq.Editor.addBlockTag(block.uuid, tag.uuid)
}

Why this pattern is popular:

• Users see a consistent “record type” (ZoteroItem) with fields.
• Plugins can be idempotent: create if missing, otherwise just reuse.

Add properties to an existing tag later

const tag = await logseq.Editor.getTag('ZoteroItem')
if (tag) {
  await logseq.Editor.addTagProperty(tag.uuid, 'zotero_key')
  await logseq.Editor.addTagProperty(tag.uuid, 'authors')
}

Tag inheritance

await logseq.Editor.addTagExtends('ZoteroItem', 'Reference')

---

7) Recommended conventions for plugin authors

Prefer DB APIs over text editing in DB graphs

• Don’t generate key:: value strings as your “source of truth” in DB mode.
• Use upsertProperty + upsertBlockProperty.

Keep keys stable; use display names for UX

• Use safe keys (snake_case, ASCII) for key.
• Use upsertProperty(key, schema, { name }) to show a nice label.

Be explicit about cardinality

• If you intend a list, set cardinality: 'many' and always write arrays.
• Use { reset: true } when you want to overwrite.

Guard DB-only APIs

• Always check App.checkCurrentIsDbGraph().

---

8) A tiny helper wrapper (optional)

If you’re building a small internal “DB properties SDK” for your plugin, a minimal shape looks like:

export async function ensureDbGraph() {
  if (!(await logseq.App.checkCurrentIsDbGraph())) {
    throw new Error('DB graph required')
  }
}

export async function ensureProperty(
  key: string,
  schema: Partial<import('../src/LSPlugin').PropertySchema>,
  name?: string
) {
  return logseq.Editor.upsertProperty(key, schema, name ? { name } : undefined)
}

export async function setProp(
  block: string,
  key: string,
  value: any,
  reset = false
) {
  return logseq.Editor.upsertBlockProperty(block, key, value, reset ? { reset: true } : undefined)
}

---

Appendix: API quick reference (from LSPlugin.ts)

Property schema (DB only)

• Editor.getProperty(key)
• Editor.upsertProperty(key, schema?, opts?)
• Editor.removeProperty(key)

Block/page values

• Editor.upsertBlockProperty(block, key, value, { reset? })
• Editor.removeBlockProperty(block, key)
• Editor.getBlockProperty(block, key)
• Editor.getBlockProperties(block)
• Editor.getPageProperties(page)

Tags / Classes

• Editor.createTag(tagName, { tagProperties? })
• Editor.getTag(nameOrIdent) / Editor.getAllTags()
• Editor.addTagProperty(tagId, propertyIdOrName) / removeTagProperty
• Editor.addTagExtends(tagId, parentTagIdOrName) / removeTagExtends
• Editor.addBlockTag(blockId, tagId) / removeBlockTag