Bases syntax

Reference for the .base file format. Learn the structure of filters, formulas, properties, summaries, and views in a base configuration file.

When you create a base in Obsidian, it is saved as a .base file. Bases are typically edited through the app interface, but you can also edit the underlying syntax directly or write it in a base code block embedded in a Markdown note.

Bases syntax is YAML-based. Filters and formulas share the same expression language.

Complete example

Here is a fully configured .base file:

filters:
  or:
    - file.hasTag("tag")
    - and:
        - file.hasTag("book")
        - file.hasLink("Textbook")
    - not:
        - file.hasTag("book")
        - file.inFolder("Required Reading")
formulas:
  formatted_price: 'if(price, price.toFixed(2) + " dollars")'
  ppu: "(price / age).toFixed(2)"
properties:
  status:
    displayName: Status
  formula.formatted_price:
    displayName: "Price"
  file.ext:
    displayName: Extension
summaries:
  customAverage: 'values.mean().round(3)'
views:
  - type: table
    name: "My table"
    limit: 10
    groupBy:
      property: note.age
      direction: DESC
    filters:
      and:
        - 'status != "done"'
        - or:
            - "formula.ppu > 5"
            - "price > 2.1"
    order:
      - file.name
      - file.ext
      - note.age
      - formula.ppu
      - formula.formatted_price
    summaries:
      formula.ppu: Average

Sections

filters

The filters section narrows which files the base includes. Without filters, a base shows every file in your vault.

Filters can be applied at two levels:

1. Global — under the top-level filters key. Applies to all views.
2. Per-view — inside an individual view’s filters key. Applies only to that view.

Both levels are combined with AND when evaluating a view.

# Simple filter
filters:
  and:
    - file.hasTag("tag")

# Complex filter with nested logic
filters:
  or:
    - file.hasTag("tag")
    - and:
        - file.hasTag("book")
        - file.hasLink("Textbook")
    - not:
        - file.hasTag("book")
        - file.inFolder("Required Reading")

A filter statement is any expression that evaluates to truthy or falsey for a given file. This includes comparisons and function calls.

formulas

The formulas section defines computed properties available across all views:

formulas:
  formatted_price: 'if(price, price.toFixed(2) + " dollars")'
  ppu: "(price / age).toFixed(2)"

Formulas are stored as strings in YAML. Use nested quotes for text literals. A formula’s output type is determined by the data and functions used — formulas are not constrained to strings at runtime.

Reference property types in formulas:

Type	Syntax	Example
Note property	property or note.property	price
File property	file.name, file.size	file.mtime
Another formula	formula.name	formula.ppu

properties

The properties section stores display configuration for properties:

properties:
  status:
    displayName: Status
  formula.formatted_price:
    displayName: "Price"
  file.ext:
    displayName: Extension

Display names are used in column headers and UI labels. They are not used in filters or formulas.

summaries

The summaries section defines custom summary formulas. In the values expression, values is a list of all values for that property across every row in the result set:

summaries:
  customAverage: 'values.mean().round(3)'

Default summary formulas are also available without defining them here:

Name	Input type	Description
Average	Number	Mean of all values
Min	Number	Smallest value
Max	Number	Largest value
Sum	Number	Total of all values
Range	Number	Difference between max and min
Median	Number	Median value
Stddev	Number	Standard deviation
Earliest	Date	Oldest date
Latest	Date	Most recent date
Range	Date	Difference between earliest and latest
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 distinct values

views

The views section is a list of view configurations:

views:
  - type: table
    name: "My table"
    limit: 10
    groupBy:
      property: note.age
      direction: DESC
    filters:
      and:
        - 'status != "done"'
    order:
      - file.name
      - note.age
    summaries:
      formula.ppu: Average

Key	Description
type	Layout type: table, list, cards, map
name	Display name for the view. Used to select a default view when embedding.
limit	Maximum number of rows to display.
filters	View-specific filters (same syntax as global filters).
groupBy	Property and direction to group results.
order	List of property names defining column order.
summaries	Map of property names to summary formula names.

Properties in bases

Bases work with three types of properties:

Note properties

Stored in the YAML frontmatter of Markdown files. Access with property_name or note.property_name:

author == "Ursula Le Guin"
note.status == "Done"

File properties

Built-in properties available for all file types:

Property	Type	Description
file.name	String	File name including extension
file.basename	String	File name without extension
file.path	String	Full path relative to vault root
file.folder	String	Path to the parent folder
file.ext	String	File extension
file.size	Number	File size in bytes
file.tags	List	Tags including inline tags
file.links	List	Internal links within the file
file.ctime	Date	Creation timestamp
file.mtime	Date	Last-modified timestamp
file.properties	Object	All frontmatter properties

this — context-aware file reference

Use this to reference the file where the base is displayed:

• Opened as a file: this refers to the .base file itself.
• Embedded in a note: this refers to the embedding note.
• In a sidebar: this refers to the active file in the main content area.

Example — replicate the backlinks panel:

filters:
  and:
    - file.hasLink(this.file)

Operators

Arithmetic

Operator	Description
+	Add
-	Subtract
*	Multiply
/	Divide
%	Modulo
( )	Parentheses (grouping)

Comparison

Operator	Description
==	Equals
!=	Not equal
>	Greater than
<	Less than
>=	Greater than or equal to
<=	Less than or equal to

Boolean

Operator	Description
!	Logical not
&&	Logical and
||	Logical or

Date arithmetic

Add or subtract durations from dates using string suffixes:

now() + "1 day"
file.mtime > now() - "1 week"
date("2024-12-01") + "1M" + "4h" + "3m"

Unit	Accepted formats
Year	y, year, years
Month	M, month, months
Day	d, day, days
Week	w, week, weeks
Hour	h, hour, hours
Minute	m, minute, minutes
Second	s, second, seconds

Subtracting two dates returns the difference in milliseconds.

Types

Type	Notes
String	Enclosed in single or double quotes: "hello", 'world'
Number	Written as digits, optionally in parentheses: 1, (2.5)
Boolean	true or false (no quotes)
Date	Created with date(), today(), or now()
List	Access elements with property[0] (0-based index)
Object	Access values with property.key or property["key"]
Link	Wikilinks in frontmatter are automatically recognized; construct with link("path")