Obsidian Bases Agent Skill

Obsidian Bases Skill

This skill enables skills-compatible agents to create and edit valid Obsidian Bases (.base files) including views, filters, formulas, and all related configurations.

Overview

Obsidian Bases are YAML-based files that define dynamic views of notes in an Obsidian vault. A Base file can contain multiple views, global filters, formulas, property configurations, and custom summaries.

File Format

Base files use the .base extension and contain valid YAML. They can also be embedded in Markdown code blocks.

Complete Schema

# Global filters apply to ALL views in the base
filters:
  # Can be a single filter string
  # OR a recursive filter object with and/or/not
  and: []
  or: []
  not: []

# Define formula properties that can be used across all views
formulas:
  formula_name: 'expression'

# Configure display names and settings for properties
properties:
  property_name:
    displayName: "Display Name"
  formula.formula_name:
    displayName: "Formula Display Name"
  file.ext:
    displayName: "Extension"

# Define custom summary formulas
summaries:
  custom_summary_name: 'values.mean().round(3)'

# Define one or more views
views:
  - type: table | cards | list | map
    name: "View Name"
    limit: 10                    # Optional: limit results
    groupBy:                     # Optional: group results
      property: property_name
      direction: ASC | DESC
    filters:                     # View-specific filters
      and: []
    order:                       # Properties to display in order
      - file.name
      - property_name
      - formula.formula_name
    summaries:                   # Map properties to summary formulas
      property_name: Average

Filter Syntax

Filters narrow down results. They can be applied globally or per-view.

Filter Structure

# Single filter
filters: 'status == "done"'

# AND - all conditions must be true
filters:
  and:
    - 'status == "done"'
    - 'priority > 3'

# OR - any condition can be true
filters:
  or:
    - 'file.hasTag("book")'
    - 'file.hasTag("article")'

# NOT - exclude matching items
filters:
  not:
    - 'file.hasTag("archived")'

# Nested filters
filters:
  or:
    - file.hasTag("tag")
    - and:
        - file.hasTag("book")
        - file.hasLink("Textbook")
    - not:
        - file.hasTag("book")
        - file.inFolder("Required Reading")

Filter Operators

| Operator | Description |

|----------|-------------|

| == | equals |

| != | not equal |

| > | greater than |

| < | less than |

| >= | greater than or equal |

| <= | less than or equal |

| && | logical and |

| \|\| | logical or |

| <code>!</code> | logical not |

Properties

Three Types of Properties

• Note properties - From frontmatter: note.author or just author
• File properties - File metadata: file.name, file.mtime, etc.
• Formula properties - Computed values: formula.my_formula

File Properties Reference

| Property | Type | Description |

|----------|------|-------------|

| file.name | String | File name |

| file.basename | String | File name without extension |

| file.path | String | Full path to file |

| file.folder | String | Parent folder path |

| file.ext | String | File extension |

| file.size | Number | File size in bytes |

| file.ctime | Date | Created time |

| file.mtime | Date | Modified time |

| file.tags | List | All tags in file |

| file.links | List | Internal links in file |

| file.backlinks | List | Files linking to this file |

| file.embeds | List | Embeds in the note |

| file.properties | Object | All frontmatter properties |

The this Keyword

• In main content area: refers to the base file itself
• When embedded: refers to the embedding file
• In sidebar: refers to the active file in main content

Formula Syntax

Formulas compute values from properties. Defined in the formulas section.

formulas:
  # Simple arithmetic
  total: "price * quantity"

  # Conditional logic
  status_icon: 'if(done, "✅", "⏳")'

  # String formatting
  formatted_price: 'if(price, price.toFixed(2) + " dollars")'

  # Date formatting
  created: 'file.ctime.format("YYYY-MM-DD")'

  # Calculate days since created (use .days for Duration)
  days_old: '(now() - file.ctime).days'

  # Calculate days until due date
  days_until_due: 'if(due_date, (date(due_date) - today()).days, "")'

Functions Reference

Global Functions

| Function | Signature | Description |

|----------|-----------|-------------|

| date() | date(string): date | Parse string to date. Format: YYYY-MM-DD HH:mm:ss |

| duration() | duration(string): duration | Parse duration string |

| now() | now(): date | Current date and time |

| today() | today(): date | Current date (time = 00:00:00) |

| if() | if(condition, trueResult, falseResult?) | Conditional |

| min() | min(n1, n2, ...): number | Smallest number |

| max() | max(n1, n2, ...): number | Largest number |

| number() | number(any): number | Convert to number |

| link() | link(path, display?): Link | Create a link |

| list() | list(element): List | Wrap in list if not already |

| file() | file(path): file | Get file object |

| image() | image(path): image | Create image for rendering |

| icon() | icon(name): icon | Lucide icon by name |

| html() | html(string): html | Render as HTML |

| escapeHTML() | escapeHTML(string): string | Escape HTML characters |

Any Type Functions

| Function | Signature | Description |

|----------|-----------|-------------|

| isTruthy() | any.isTruthy(): boolean | Coerce to boolean |

| isType() | any.isType(type): boolean | Check type |

| toString() | any.toString(): string | Convert to string |

Date Functions & Fields

Fields: date.year, date.month, date.day, date.hour, date.minute, date.second, date.millisecond

| Function | Signature | Description |

|----------|-----------|-------------|

| date() | date.date(): date | Remove time portion |

| format() | date.format(string): string | Format with Moment.js pattern |

| time() | date.time(): string | Get time as string |

| relative() | date.relative(): string | Human-readable relative time |

| isEmpty() | date.isEmpty(): boolean | Always false for dates |

Duration Type

When subtracting two dates, the result is a Duration type (not a number). Duration has its own properties and methods.

Duration Fields:

| Field | Type | Description |

|-------|------|-------------|

| duration.days | Number | Total days in duration |

| duration.hours | Number | Total hours in duration |

| duration.minutes | Number | Total minutes in duration |

| duration.seconds | Number | Total seconds in duration |

| duration.milliseconds | Number | Total milliseconds in duration |

IMPORTANT: Duration does NOT support .round(), .floor(), .ceil() directly. You must access a numeric field first (like .days), then apply number functions.

# CORRECT: Calculate days between dates
"(date(due_date) - today()).days"                    # Returns number of days
"(now() - file.ctime).days"                          # Days since created

# CORRECT: Round the numeric result if needed
"(date(due_date) - today()).days.round(0)"           # Rounded days
"(now() - file.ctime).hours.round(0)"                # Rounded hours

# WRONG - will cause error:
# "((date(due) - today()) / 86400000).round(0)"      # Duration doesn't support division then round

Date Arithmetic

# Duration units: y/year/years, M/month/months, d/day/days,
#                 w/week/weeks, h/hour/hours, m/minute/minutes, s/second/seconds

# Add/subtract durations
"date + \"1M\""           # Add 1 month
"date - \"2h\""           # Subtract 2 hours
"now() + \"1 day\""       # Tomorrow
"today() + \"7d\""        # A week from today

# Subtract dates returns Duration type
"now() - file.ctime"                    # Returns Duration
"(now() - file.ctime).days"             # Get days as number
"(now() - file.ctime).hours"            # Get hours as number

# Complex duration arithmetic
"now() + (duration('1d') * 2)"

String Functions

Field: string.length

| Function | Signature | Description |

|----------|-----------|-------------|

| contains() | string.contains(value): boolean | Check substring |

| containsAll() | string.containsAll(...values): boolean | All substrings present |

| containsAny() | string.containsAny(...values): boolean | Any substring present |

| startsWith() | string.startsWith(query): boolean | Starts with query |

| endsWith() | string.endsWith(query): boolean | Ends with query |

| isEmpty() | string.isEmpty(): boolean | Empty or not present |

| lower() | string.lower(): string | To lowercase |

| title() | string.title(): string | To Title Case |

| trim() | string.trim(): string | Remove whitespace |

| replace() | string.replace(pattern, replacement): string | Replace pattern |

| repeat() | string.repeat(count): string | Repeat string |

| reverse() | string.reverse(): string | Reverse string |

| slice() | string.slice(start, end?): string | Substring |

| split() | string.split(separator, n?): list | Split to list |

Number Functions

| Function | Signature | Description |

|----------|-----------|-------------|

| abs() | number.abs(): number | Absolute value |

| ceil() | number.ceil(): number | Round up |

| floor() | number.floor(): number | Round down |

| round() | number.round(digits?): number | Round to digits |

| toFixed() | number.toFixed(precision): string | Fixed-point notation |

| isEmpty() | number.isEmpty(): boolean | Not present |

List Functions

Field: list.length

| Function | Signature | Description |

|----------|-----------|-------------|

| contains() | list.contains(value): boolean | Element exists |

| containsAll() | list.containsAll(...values): boolean | All elements exist |

| containsAny() | list.containsAny(...values): boolean | Any element exists |

| filter() | list.filter(expression): list | Filter by condition (uses value, index) |

| map() | list.map(expression): list | Transform elements (uses value, index) |

| reduce() | list.reduce(expression, initial): any | Reduce to single value (uses value, index, acc) |

| flat() | list.flat(): list | Flatten nested lists |

| join() | list.join(separator): string | Join to string |

| reverse() | list.reverse(): list | Reverse order |

| slice() | list.slice(start, end?): list | Sublist |

| sort() | list.sort(): list | Sort ascending |

| unique() | list.unique(): list | Remove duplicates |

| isEmpty() | list.isEmpty(): boolean | No elements |

File Functions

| Function | Signature | Description |

|----------|-----------|-------------|

| asLink() | file.asLink(display?): Link | Convert to link |

| hasLink() | file.hasLink(otherFile): boolean | Has link to file |

| hasTag() | file.hasTag(...tags): boolean | Has any of the tags |

| hasProperty() | file.hasProperty(name): boolean | Has property |

| inFolder() | file.inFolder(folder): boolean | In folder or subfolder |

Link Functions

| Function | Signature | Description |

|----------|-----------|-------------|

| asFile() | link.asFile(): file | Get file object |

| linksTo() | link.linksTo(file): boolean | Links to file |

Object Functions

| Function | Signature | Description |

|----------|-----------|-------------|

| isEmpty() | object.isEmpty(): boolean | No properties |

| keys() | object.keys(): list | List of keys |

| values() | object.values(): list | List of values |

Regular Expression Functions

| Function | Signature | Description |

|----------|-----------|-------------|

| matches() | regexp.matches(string): boolean | Test if matches |

View Types

Table View

views:
  - type: table
    name: "My Table"
    order:
      - file.name
      - status
      - due_date
    summaries:
      price: Sum
      count: Average

Cards View

views:
  - type: cards
    name: "Gallery"
    order:
      - file.name
      - cover_image
      - description

List View

views:
  - type: list
    name: "Simple List"
    order:
      - file.name
      - status

Map View

Requires latitude/longitude properties and the Maps community plugin.

views:
  - type: map
    name: "Locations"
    # Map-specific settings for lat/lng properties

Default Summary Formulas

| Name | Input Type | Description |

|------|------------|-------------|

| Average | Number | Mathematical mean |

| Min | Number | Smallest number |

| Max | Number | Largest number |

| Sum | Number | Sum of all numbers |

| Range | Number | Max - Min |

| Median | Number | Mathematical median |

| Stddev | Number | Standard deviation |

| Earliest | Date | Earliest date |

| Latest | Date | Latest date |

| Range | Date | Latest - Earliest |

| Checked | Boolean | Count of true values |

| Unchecked | Boolean | Count of false values |

| Empty | Any | Count of empty values |

| Filled | Any | Count of non-empty values |

| Unique | Any | Count of unique values |

Complete Examples

Task Tracker Base

filters:
  and:
    - file.hasTag("task")
    - 'file.ext == "md"'

formulas:
  days_until_due: 'if(due, (date(due) - today()).days, "")'
  is_overdue: 'if(due, date(due) < today() && status != "done", false)'
  priority_label: 'if(priority == 1, "🔴 High", if(priority == 2, "🟡 Medium", "🟢 Low"))'

properties:
  status:
    displayName: Status
  formula.days_until_due:
    displayName: "Days Until Due"
  formula.priority_label:
    displayName: Priority

views:
  - type: table
    name: "Active Tasks"
    filters:
      and:
        - 'status != "done"'
    order:
      - file.name
      - status
      - formula.priority_label
      - due
      - formula.days_until_due
    groupBy:
      property: status
      direction: ASC
    summaries:
      formula.days_until_due: Average

  - type: table
    name: "Completed"
    filters:
      and:
        - 'status == "done"'
    order:
      - file.name
      - completed_date

Reading List Base

filters:
  or:
    - file.hasTag("book")
    - file.hasTag("article")

formulas:
  reading_time: 'if(pages, (pages * 2).toString() + " min", "")'
  status_icon: 'if(status == "reading", "📖", if(status == "done", "✅", "📚"))'
  year_read: 'if(finished_date, date(finished_date).year, "")'

properties:
  author:
    displayName: Author
  formula.status_icon:
    displayName: ""
  formula.reading_time:
    displayName: "Est. Time"

views:
  - type: cards
    name: "Library"
    order:
      - cover
      - file.name
      - author
      - formula.status_icon
    filters:
      not:
        - 'status == "dropped"'

  - type: table
    name: "Reading List"
    filters:
      and:
        - 'status == "to-read"'
    order:
      - file.name
      - author
      - pages
      - formula.reading_time

Project Notes Base

filters:
  and:
    - file.inFolder("Projects")
    - 'file.ext == "md"'

formulas:
  last_updated: 'file.mtime.relative()'
  link_count: 'file.links.length'

summaries:
  avgLinks: 'values.filter(value.isType("number")).mean().round(1)'

properties:
  formula.last_updated:
    displayName: "Updated"
  formula.link_count:
    displayName: "Links"

views:
  - type: table
    name: "All Projects"
    order:
      - file.name
      - status
      - formula.last_updated
      - formula.link_count
    summaries:
      formula.link_count: avgLinks
    groupBy:
      property: status
      direction: ASC

  - type: list
    name: "Quick List"
    order:
      - file.name
      - status

Daily Notes Index

filters:
  and:
    - file.inFolder("Daily Notes")
    - '/^\d{4}-\d{2}-\d{2}$/.matches(file.basename)'

formulas:
  word_estimate: '(file.size / 5).round(0)'
  day_of_week: 'date(file.basename).format("dddd")'

properties:
  formula.day_of_week:
    displayName: "Day"
  formula.word_estimate:
    displayName: "~Words"

views:
  - type: table
    name: "Recent Notes"
    limit: 30
    order:
      - file.name
      - formula.day_of_week
      - formula.word_estimate
      - file.mtime

Embedding Bases

Embed in Markdown files:

![[MyBase.base]]

<!-- Specific view -->
![[MyBase.base#View Name]]

YAML Quoting Rules

• Use single quotes for formulas containing double quotes: 'if(done, "Yes", "No")'
• Use double quotes for simple strings: "My View Name"
• Escape nested quotes properly in complex expressions

Common Patterns

Filter by Tag

filters:
  and:
    - file.hasTag("project")

Filter by Folder

filters:
  and:
    - file.inFolder("Notes")

Filter by Date Range

filters:
  and:
    - 'file.mtime > now() - "7d"'

Filter by Property Value

filters:
  and:
    - 'status == "active"'
    - 'priority >= 3'

Combine Multiple Conditions

filters:
  or:
    - and:
        - file.hasTag("important")
        - 'status != "done"'
    - and:
        - 'priority == 1'
        - 'due != ""'

References

• Bases Syntax
• Functions
• Views
• Formulas