Agent-Skills.md

Agent Skills: Obsidian Bases Skill

Create and edit Obsidian Bases (.base files) with views, filters, formulas, and summaries. Use when working with .base files, creating database-like views of notes, or when the user mentions Bases, table views, card views, filters, or formulas in Obsidian.

UncategorizedID: kepano/obsidian-skills/obsidian-bases

Repository

kepano/obsidian-skills
kepano

Install this agent skill to your local

pnpm dlx add-skill https://github.com/kepano/obsidian-skills/tree/HEAD/skills/obsidian-bases

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skills/obsidian-bases/SKILL.md

Skill Metadata

Name
obsidian-bases
Description
Create and edit Obsidian Bases (.base files) with views, filters, formulas, and summaries. Use when working with .base files, creating database-like views of notes, or when the user mentions Bases, table views, card views, filters, or formulas in Obsidian.

Obsidian Bases Skill

Workflow

  1. Create the file: Create a .base file in the vault with valid YAML content
  2. Define scope: Add filters to select which notes appear (by tag, folder, property, or date)
  3. Add formulas (optional): Define computed properties in the formulas section
  4. Configure views: Add one or more views (table, cards, list, or map) with order specifying which properties to display
  5. Validate: Verify the file is valid YAML with no syntax errors. Check that all referenced properties and formulas exist. Common issues: unquoted strings containing special YAML characters, mismatched quotes in formula expressions, referencing formula.X without defining X in formulas
  6. Test in Obsidian: Open the .base file in Obsidian to confirm the view renders correctly. If it shows a YAML error, check quoting rules below

Schema

Base files use the .base extension and contain valid YAML.

# 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

  1. Note properties - From frontmatter: note.author or just author
  2. File properties - File metadata: file.name, file.mtime, etc.
  3. 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, "")'

Key Functions

Most commonly used functions. For the complete reference of all types (Date, String, Number, List, File, Link, Object, RegExp), see FUNCTIONS_REFERENCE.md.

| Function | Signature | Description | |----------|-----------|-------------| | date() | date(string): date | Parse string to date (YYYY-MM-DD HH:mm:ss) | | now() | now(): date | Current date and time | | today() | today(): date | Current date (time = 00:00:00) | | if() | if(condition, trueResult, falseResult?) | Conditional | | duration() | duration(string): duration | Parse duration string | | file() | file(path): file | Get file object | | link() | link(path, display?): Link | Create a link |

Duration Type

When subtracting two dates, the result is a Duration type (not a number).

Duration Fields: duration.days, duration.hours, duration.minutes, duration.seconds, duration.milliseconds

IMPORTANT: Duration does NOT support .round(), .floor(), .ceil() directly. 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
"(date(due_date) - today()).days.round(0)"           # Rounded days

# 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
"now() + \"1 day\""       # Tomorrow
"today() + \"7d\""        # A week from today
"now() - file.ctime"      # Returns Duration
"(now() - file.ctime).days"  # Get days as number

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

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

Troubleshooting

YAML Syntax Errors

Unquoted special characters: Strings containing :, {, }, [, ], ,, &, *, #, ?, |, -, <, >, =, !, %, @, ` must be quoted.

# WRONG - colon in unquoted string
displayName: Status: Active

# CORRECT
displayName: "Status: Active"

Mismatched quotes in formulas: When a formula contains double quotes, wrap the entire formula in single quotes.

# WRONG - double quotes inside double quotes
formulas:
  label: "if(done, "Yes", "No")"

# CORRECT - single quotes wrapping double quotes
formulas:
  label: 'if(done, "Yes", "No")'

Common Formula Errors

Duration math without field access: Subtracting dates returns a Duration, not a number. Always access .days, .hours, etc.

# WRONG - Duration is not a number
"(now() - file.ctime).round(0)"

# CORRECT - access .days first, then round
"(now() - file.ctime).days.round(0)"

Missing null checks: Properties may not exist on all notes. Use if() to guard.

# WRONG - crashes if due_date is empty
"(date(due_date) - today()).days"

# CORRECT - guard with if()
'if(due_date, (date(due_date) - today()).days, "")'

Referencing undefined formulas: Ensure every formula.X in order or properties has a matching entry in formulas.

# This will fail silently if 'total' is not defined in formulas
order:
  - formula.total

# Fix: define it
formulas:
  total: "price * quantity"

References