1---
2name: obsidian-bases
3description: 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.
4---
5 
6# Obsidian Bases Skill
7 
8## Workflow
9 
101. **Create the file**: Create a `.base` file in the vault with valid YAML content
112. **Define scope**: Add `filters` to select which notes appear (by tag, folder, property, or date)
123. **Add formulas** (optional): Define computed properties in the `formulas` section
134. **Configure views**: Add one or more views (`table`, `cards`, `list`, or `map`) with `order` specifying which properties to display
145. **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`
156. **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
16 
17## Schema
18 
19Base files use the `.base` extension and contain valid YAML.
20 
21```yaml
22# Global filters apply to ALL views in the base
23filters:
24  # Can be a single filter string
25  # OR a recursive filter object with and/or/not
26  and: []
27  or: []
28  not: []
29 
30# Define formula properties that can be used across all views
31formulas:
32  formula_name: 'expression'
33 
34# Configure display names and settings for properties
35properties:
36  property_name:
37    displayName: "Display Name"
38  formula.formula_name:
39    displayName: "Formula Display Name"
40  file.ext:
41    displayName: "Extension"
42 
43# Define custom summary formulas
44summaries:
45  custom_summary_name: 'values.mean().round(3)'
46 
47# Define one or more views
48views:
49  - type: table | cards | list | map
50    name: "View Name"
51    limit: 10                    # Optional: limit results
52    groupBy:                     # Optional: group results
53      property: property_name
54      direction: ASC | DESC
55    filters:                     # View-specific filters
56      and: []
57    order:                       # Properties to display in order
58      - file.name
59      - property_name
60      - formula.formula_name
61    summaries:                   # Map properties to summary formulas
62      property_name: Average
63```
64 
65## Filter Syntax
66 
67Filters narrow down results. They can be applied globally or per-view.
68 
69### Filter Structure
70 
71```yaml
72# Single filter
73filters: 'status == "done"'
74 
75# AND - all conditions must be true
76filters:
77  and:
78    - 'status == "done"'
79    - 'priority > 3'
80 
81# OR - any condition can be true
82filters:
83  or:
84    - 'file.hasTag("book")'
85    - 'file.hasTag("article")'
86 
87# NOT - exclude matching items
88filters:
89  not:
90    - 'file.hasTag("archived")'
91 
92# Nested filters
93filters:
94  or:
95    - file.hasTag("tag")
96    - and:
97        - file.hasTag("book")
98        - file.hasLink("Textbook")
99    - not:
100        - file.hasTag("book")
101        - file.inFolder("Required Reading")
102```
103 
104### Filter Operators
105 
106| Operator | Description |
107|----------|-------------|
108| `==` | equals |
109| `!=` | not equal |
110| `>` | greater than |
111| `<` | less than |
112| `>=` | greater than or equal |
113| `<=` | less than or equal |
114| `&&` | logical and |
115| `\|\|` | logical or |
116| <code>!</code> | logical not |
117 
118## Properties
119 
120### Three Types of Properties
121 
1221. **Note properties** - From frontmatter: `note.author` or just `author`
1232. **File properties** - File metadata: `file.name`, `file.mtime`, etc.
1243. **Formula properties** - Computed values: `formula.my_formula`
125 
126### File Properties Reference
127 
128| Property | Type | Description |
129|----------|------|-------------|
130| `file.name` | String | File name |
131| `file.basename` | String | File name without extension |
132| `file.path` | String | Full path to file |
133| `file.folder` | String | Parent folder path |
134| `file.ext` | String | File extension |
135| `file.size` | Number | File size in bytes |
136| `file.ctime` | Date | Created time |
137| `file.mtime` | Date | Modified time |
138| `file.tags` | List | All tags in file |
139| `file.links` | List | Internal links in file |
140| `file.backlinks` | List | Files linking to this file |
141| `file.embeds` | List | Embeds in the note |
142| `file.properties` | Object | All frontmatter properties |
143 
144### The `this` Keyword
145 
146- In main content area: refers to the base file itself
147- When embedded: refers to the embedding file
148- In sidebar: refers to the active file in main content
149 
150## Formula Syntax
151 
152Formulas compute values from properties. Defined in the `formulas` section.
153 
154```yaml
155formulas:
156  # Simple arithmetic
157  total: "price * quantity"
158 
159  # Conditional logic
160  status_icon: 'if(done, "✅", "⏳")'
161 
162  # String formatting
163  formatted_price: 'if(price, price.toFixed(2) + " dollars")'
164 
165  # Date formatting
166  created: 'file.ctime.format("YYYY-MM-DD")'
167 
168  # Calculate days since created (use .days for Duration)
169  days_old: '(now() - file.ctime).days'
170 
171  # Calculate days until due date
172  days_until_due: 'if(due_date, (date(due_date) - today()).days, "")'
173```
174 
175## Key Functions
176 
177Most 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).
178 
179| Function | Signature | Description |
180|----------|-----------|-------------|
181| `date()` | `date(string): date` | Parse string to date (`YYYY-MM-DD HH:mm:ss`) |
182| `now()` | `now(): date` | Current date and time |
183| `today()` | `today(): date` | Current date (time = 00:00:00) |
184| `if()` | `if(condition, trueResult, falseResult?)` | Conditional |
185| `duration()` | `duration(string): duration` | Parse duration string |
186| `file()` | `file(path): file` | Get file object |
187| `link()` | `link(path, display?): Link` | Create a link |
188 
189### Duration Type
190 
191When subtracting two dates, the result is a **Duration** type (not a number).
192 
193**Duration Fields:** `duration.days`, `duration.hours`, `duration.minutes`, `duration.seconds`, `duration.milliseconds`
194 
195**IMPORTANT:** Duration does NOT support `.round()`, `.floor()`, `.ceil()` directly. Access a numeric field first (like `.days`), then apply number functions.
196 
197```yaml
198# CORRECT: Calculate days between dates
199"(date(due_date) - today()).days"                    # Returns number of days
200"(now() - file.ctime).days"                          # Days since created
201"(date(due_date) - today()).days.round(0)"           # Rounded days
202 
203# WRONG - will cause error:
204# "((date(due) - today()) / 86400000).round(0)"      # Duration doesn't support division then round
205```
206 
207### Date Arithmetic
208 
209```yaml
210# Duration units: y/year/years, M/month/months, d/day/days,
211#                 w/week/weeks, h/hour/hours, m/minute/minutes, s/second/seconds
212"now() + \"1 day\""       # Tomorrow
213"today() + \"7d\""        # A week from today
214"now() - file.ctime"      # Returns Duration
215"(now() - file.ctime).days"  # Get days as number
216```
217 
218## View Types
219 
220### Table View
221 
222```yaml
223views:
224  - type: table
225    name: "My Table"
226    order:
227      - file.name
228      - status
229      - due_date
230    summaries:
231      price: Sum
232      count: Average
233```
234 
235### Cards View
236 
237```yaml
238views:
239  - type: cards
240    name: "Gallery"
241    order:
242      - file.name
243      - cover_image
244      - description
245```
246 
247### List View
248 
249```yaml
250views:
251  - type: list
252    name: "Simple List"
253    order:
254      - file.name
255      - status
256```
257 
258### Map View
259 
260Requires latitude/longitude properties and the Maps community plugin.
261 
262```yaml
263views:
264  - type: map
265    name: "Locations"
266    # Map-specific settings for lat/lng properties
267```
268 
269## Default Summary Formulas
270 
271| Name | Input Type | Description |
272|------|------------|-------------|
273| `Average` | Number | Mathematical mean |
274| `Min` | Number | Smallest number |
275| `Max` | Number | Largest number |
276| `Sum` | Number | Sum of all numbers |
277| `Range` | Number | Max - Min |
278| `Median` | Number | Mathematical median |
279| `Stddev` | Number | Standard deviation |
280| `Earliest` | Date | Earliest date |
281| `Latest` | Date | Latest date |
282| `Range` | Date | Latest - Earliest |
283| `Checked` | Boolean | Count of true values |
284| `Unchecked` | Boolean | Count of false values |
285| `Empty` | Any | Count of empty values |
286| `Filled` | Any | Count of non-empty values |
287| `Unique` | Any | Count of unique values |
288 
289## Complete Examples
290 
291### Task Tracker Base
292 
293```yaml
294filters:
295  and:
296    - file.hasTag("task")
297    - 'file.ext == "md"'
298 
299formulas:
300  days_until_due: 'if(due, (date(due) - today()).days, "")'
301  is_overdue: 'if(due, date(due) < today() && status != "done", false)'
302  priority_label: 'if(priority == 1, "🔴 High", if(priority == 2, "🟡 Medium", "🟢 Low"))'
303 
304properties:
305  status:
306    displayName: Status
307  formula.days_until_due:
308    displayName: "Days Until Due"
309  formula.priority_label:
310    displayName: Priority
311 
312views:
313  - type: table
314    name: "Active Tasks"
315    filters:
316      and:
317        - 'status != "done"'
318    order:
319      - file.name
320      - status
321      - formula.priority_label
322      - due
323      - formula.days_until_due
324    groupBy:
325      property: status
326      direction: ASC
327    summaries:
328      formula.days_until_due: Average
329 
330  - type: table
331    name: "Completed"
332    filters:
333      and:
334        - 'status == "done"'
335    order:
336      - file.name
337      - completed_date
338```
339 
340### Reading List Base
341 
342```yaml
343filters:
344  or:
345    - file.hasTag("book")
346    - file.hasTag("article")
347 
348formulas:
349  reading_time: 'if(pages, (pages * 2).toString() + " min", "")'
350  status_icon: 'if(status == "reading", "📖", if(status == "done", "✅", "📚"))'
351  year_read: 'if(finished_date, date(finished_date).year, "")'
352 
353properties:
354  author:
355    displayName: Author
356  formula.status_icon:
357    displayName: ""
358  formula.reading_time:
359    displayName: "Est. Time"
360 
361views:
362  - type: cards
363    name: "Library"
364    order:
365      - cover
366      - file.name
367      - author
368      - formula.status_icon
369    filters:
370      not:
371        - 'status == "dropped"'
372 
373  - type: table
374    name: "Reading List"
375    filters:
376      and:
377        - 'status == "to-read"'
378    order:
379      - file.name
380      - author
381      - pages
382      - formula.reading_time
383```
384 
385### Daily Notes Index
386 
387```yaml
388filters:
389  and:
390    - file.inFolder("Daily Notes")
391    - '/^\d{4}-\d{2}-\d{2}$/.matches(file.basename)'
392 
393formulas:
394  word_estimate: '(file.size / 5).round(0)'
395  day_of_week: 'date(file.basename).format("dddd")'
396 
397properties:
398  formula.day_of_week:
399    displayName: "Day"
400  formula.word_estimate:
401    displayName: "~Words"
402 
403views:
404  - type: table
405    name: "Recent Notes"
406    limit: 30
407    order:
408      - file.name
409      - formula.day_of_week
410      - formula.word_estimate
411      - file.mtime
412```
413 
414## Embedding Bases
415 
416Embed in Markdown files:
417 
418```markdown
419![[MyBase.base]]
420 
421<!-- Specific view -->
422![[MyBase.base#View Name]]
423```
424 
425## YAML Quoting Rules
426 
427- Use single quotes for formulas containing double quotes: `'if(done, "Yes", "No")'`
428- Use double quotes for simple strings: `"My View Name"`
429- Escape nested quotes properly in complex expressions
430 
431## Troubleshooting
432 
433### YAML Syntax Errors
434 
435**Unquoted special characters**: Strings containing `:`, `{`, `}`, `[`, `]`, `,`, `&`, `*`, `#`, `?`, `|`, `-`, `<`, `>`, `=`, `!`, `%`, `@`, `` ` `` must be quoted.
436 
437```yaml
438# WRONG - colon in unquoted string
439displayName: Status: Active
440 
441# CORRECT
442displayName: "Status: Active"
443```
444 
445**Mismatched quotes in formulas**: When a formula contains double quotes, wrap the entire formula in single quotes.
446 
447```yaml
448# WRONG - double quotes inside double quotes
449formulas:
450  label: "if(done, "Yes", "No")"
451 
452# CORRECT - single quotes wrapping double quotes
453formulas:
454  label: 'if(done, "Yes", "No")'
455```
456 
457### Common Formula Errors
458 
459**Duration math without field access**: Subtracting dates returns a Duration, not a number. Always access `.days`, `.hours`, etc.
460 
461```yaml
462# WRONG - Duration is not a number
463"(now() - file.ctime).round(0)"
464 
465# CORRECT - access .days first, then round
466"(now() - file.ctime).days.round(0)"
467```
468 
469**Missing null checks**: Properties may not exist on all notes. Use `if()` to guard.
470 
471```yaml
472# WRONG - crashes if due_date is empty
473"(date(due_date) - today()).days"
474 
475# CORRECT - guard with if()
476'if(due_date, (date(due_date) - today()).days, "")'
477```
478 
479**Referencing undefined formulas**: Ensure every `formula.X` in `order` or `properties` has a matching entry in `formulas`.
480 
481```yaml
482# This will fail silently if 'total' is not defined in formulas
483order:
484  - formula.total
485 
486# Fix: define it
487formulas:
488  total: "price * quantity"
489```
490 
491## References
492 
493- [Bases Syntax](https://help.obsidian.md/bases/syntax)
494- [Functions](https://help.obsidian.md/bases/functions)
495- [Views](https://help.obsidian.md/bases/views)
496- [Formulas](https://help.obsidian.md/formulas)
497- [Complete Functions Reference](references/FUNCTIONS_REFERENCE.md)
498