---
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.

```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

```yaml
# 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 |
| `!` | 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.

```yaml
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](references/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.

```yaml
# 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
```

## View Types

### Table View

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

### Cards View

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

### List View

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

## 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 |
| `Median` | Number | Mathematical median |
| `Earliest` | Date | Earliest date |
| `Latest` | Date | Latest date |
| `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 |

## 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

## References

- [Bases Syntax](https://help.obsidian.md/bases/syntax)
- [Functions](https://help.obsidian.md/bases/functions)
- [Views](https://help.obsidian.md/bases/views)
- [Complete Functions Reference](references/FUNCTIONS_REFERENCE.md)