---
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, kanban boards, 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`, `map`, or `kanban`) 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. If it doesn't open as a base at all, check that Bases is turned on in Settings → Core plugins

## 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 exactly ONE key: and, or, or not
  and:
    - 'status == "active"'
    - not:
        - 'file.hasTag("archived")'

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

# Configure display names and settings for properties.
# Note properties need the `note.` prefix here, or the setting is ignored.
properties:
  note.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 | kanban
    name: "View Name"
    limit: 10                    # Optional: limit results
    groupBy:                     # Optional: group results
      property: property_name
      direction: ASC | DESC
    groupOrder:                  # Optional: only these groups, in this order
      - value_one
      - null                     # Files with no value for the groupBy property
    sort:                        # Optional: sort results (supports multiple properties)
      - property: property_name
        direction: ASC | DESC
    filters:                     # View-specific filters follow the same rules
      and:
        - 'status == "active"'
    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 |
| <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`

In `order`, `filters`, `groupBy`, and `sort`, a note property can be written bare (`author`) or prefixed (`note.author`). In the top-level `properties:` section, always write `note.author`, because Obsidian ignores a bare key there and shows the raw name as the column header.

### 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. Slow in large vaults and doesn't refresh when the vault changes; prefer reversing the lookup with `file.links` |
| `file.embeds` | List | Embeds in the note |
| `file.properties` | Object | All frontmatter properties. Doesn't refresh when the vault changes |
| `file.file` | File | File object, only usable in specific functions |

### 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

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

### Date Arithmetic

```yaml
# 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

```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
```

### Kanban View

Requires Obsidian 1.14+. Cards are grouped into columns by the `groupBy` property, which a kanban view needs. `groupOrder` sets which columns show and in what order; use `null` to include files with no value. Without `groupOrder`, every value gets a column. Dragging a card to another column updates that property in the note. Only Markdown notes can be moved, except when grouping by `file.folder`, where moving a card moves the file to that folder. When grouping by a formula or by a file property other than `file.folder`, cards and columns can't be moved and notes can't be created from a column.

```yaml
views:
  - type: kanban
    name: "Projects"
    groupBy:
      property: note.status
      direction: ASC
    groupOrder:
      - Planned
      - In progress
      - Done
    order:
      - file.name
      - due_date
```

### Map View

Requires latitude/longitude properties and the Maps community plugin.

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

## Sorting

Sort results by one or more properties. Each sort entry specifies a `property` and `direction`, which must be uppercase `ASC` or `DESC`; an entry with any other value, or a sort written as a string, is silently ignored. Multiple sort entries are applied in order — the first entry is the primary sort key, subsequent entries break ties.

```yaml
views:
  - type: table
    name: "Sorted Tasks"
    sort:
      - property: due
        direction: ASC
      - property: file.name
        direction: ASC
    order:
      - file.name
      - due
      - status
```

Sort options depend on the property type:

| Property Type | ASC | DESC |
|---------------|-----|------|
| Text | A→Z | Z→A |
| Number | 0→9 | 9→0 |
| Date | Old→New | New→Old |

You can sort by any property including formulas (`formula.my_formula`), file properties (`file.mtime`), and note 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

```yaml
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:
  note.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
    sort:
      - property: due
        direction: ASC
      - property: file.name
        direction: ASC
    summaries:
      formula.days_until_due: Average

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

### Reading List Base

```yaml
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:
  note.author:
    displayName: Author
  formula.status_icon:
    displayName: "Status"
  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

```yaml
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 a `.base` file

Embed an external `.base` file in any Markdown note:

```markdown
![[MyBase.base]]

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

### Embed inline with a code block

Bases can also be embedded **inline** directly inside a note using a `base` fenced code block. This is useful for note-level filters (e.g. using `this.file.links`) and avoids creating a separate `.base` file:

````markdown
```base
filters:
  and:
    - file.hasTag("example")
views:
  - type: table
    name: Table
    order:
      - file.name
      - status
```
````

When embedded inline this way, the `this` keyword refers to the containing note, so you can build per-note views such as showing all notes linked from the current file.

## 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.

```yaml
# 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.

```yaml
# 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.

```yaml
# 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.

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

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

**`displayName` ignored, column shows the raw name**: prefix note properties with `note.` in the `properties:` section.

```yaml
# WRONG - displayName ignored, column header shows "status"
properties:
  status:
    displayName: Status

# CORRECT - column header shows "Status"
properties:
  note.status:
    displayName: Status
```

**Empty `displayName` doesn't hide a header**: `displayName: ""` falls back to the property name, the same as leaving it out, so `formula.status_icon` shows `status_icon`. Use a non-empty name such as `displayName: "Status"`.

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

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

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

## References

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