obsidian-bases

Obsidian Bases

Overview

Obsidian Bases is a native database/spreadsheet feature introduced in Obsidian 1.x. A .base file is a YAML document that defines filtered, formula-enriched, grouped views over vault notes. This skill provides authoritative Bases syntax — filters, formulas, property namespaces, view types, and summaries — so edits to .base files produce valid, working queries.

When to Use

Invoke when the user mentions .base files, Bases views, filter formulas, vault-level databases, or asks to build a query that lists/groups/summarizes notes across the vault.

When NOT to use

• Dataview queries (DQL, TABLE, LIST, WHERE syntax, or JavaScript views) — different query language, not Bases.
• Standard frontmatter edits on a single note — no Bases file involved.
• Obsidian plugin development or community plugin config — Bases is a core feature, not a plugin.

Core Process

1. Read vault CLAUDE.md (if present) for custom property naming conventions before writing any formula. Property names in formulas must match the vault's frontmatter keys exactly.
2. Determine filter criteria — which notes the view should include. Translate the user's intent into file.hasTag, file.inFolder, frontmatter property comparisons, or compound and/or/not blocks.
3. Define properties, formulas, and view type — pick table, cards, list, or map; list the columns/fields; add formulas for any computed values.
4. Watch for Duration pitfalls — subtracting two dates returns a Duration, not a Number. Always chain .days / .hours / .minutes before feeding into numeric functions or display.

Techniques

File structure. A .base file is valid YAML with these optional top-level keys: filters, formulas, properties, summaries, views.

Filters.

filters: "file.hasTag('project')"

filters:
  and:
    - "file.hasTag('project')"
    - "file.inFolder('02 - Areas')"

filters:
  not: "file.hasTag('archived')"

Filter functions: file.hasTag(tag), file.hasLink(note), file.inFolder(path), .matches(regex). Logical operators inside strings: &&, ||, !.

Property namespaces.

• Note frontmatter: propertyName (direct, unqualified).
• File metadata: file.name, file.basename, file.path, file.folder, file.ext, file.size, file.ctime, file.mtime, file.tags, file.links, file.backlinks, file.embeds, file.properties.
• Computed: formula.formulaName.
• this resolves to the current note in main content, the embed host inside an embed, and the sidebar target when viewed in the sidebar.

Formulas.

formulas:
  age: "date.now() - file.ctime"
  daysSinceModified: "(date.now() - file.mtime).days"

Duration pitfall: date.now() - file.mtime returns a Duration. Access .days, .hours, .minutes, etc., before passing to numeric functions, rounding, or comparisons against numbers.

Views.

views:
  - type: table
    name: "All Notes"
    properties: [file.name, status, file.mtime]
    sort: [{property: file.mtime, direction: desc}]
    groupBy: status

View types: table, cards, list, map.

Summaries.

summaries:
  status:
    formula: count

Built-in summary formulas: Average, Min, Max, Sum, Range, Median, Stddev, Earliest, Latest, Checked, Unchecked, Empty, Filled, Unique, Count.

Embedding.

• ![[MyBase.base]] embeds the full base.
• ![[MyBase.base#View Name]] embeds a specific named view.

YAML quoting. When a formula string contains double quotes, wrap the string in single quotes:

formulas:
  label: 'if(status == "done", "done", "open")'

Reference: grep references/functions-reference.md for formula function signatures by return type (Date, Duration, String, Number, Boolean, List, File). Do not load the full file — grep for the function name or category you need.

Common Rationalizations

N/A — reference skill, not discipline.

Red Flags

• Using (date.now() - file.mtime) directly as a number — must access .days / .hours / etc. Duration is not a Number.
• Using DQL keywords (TABLE, FROM, WHERE, SORT) — that is Dataview, not Bases. Bases uses YAML with filter functions.
• Wrapping a formula string in double quotes when the formula itself contains double quotes — YAML parse error. Use single quotes around the outer string.
• Using tag: (singular frontmatter-style) inside a filter expression instead of file.hasTag() — filter context needs the function call form.
• Referencing a frontmatter property with the file. prefix (e.g., file.status) — frontmatter properties are unqualified. file. is reserved for file metadata.

Verification

To confirm the skill was applied correctly, output a sample .base snippet that lists all notes with tag project, sorted by file.mtime descending, showing name and status columns. The snippet should parse as valid YAML and use only the namespaces and functions documented above.