Data Annotation

Dataview is a data index first and foremost, so it supports relatively rich ways of adding metadata to your knowledge base. Dataview tracks information at the markdown page and markdown task levels, where each page/task can have an arbitrary amount of complex (numbers, objects, lists) fields associated with it. Each field is a named value with a certain type (like "number" or "text").

Pages

You can add fields to a markdown page in three different ways:

Frontmatter: Frontmatter is a common Markdown extension which allows for YAML metadata to be added to the top of a page. All YAML fields will be available as Dataview fields:
```
---
alias: "document"
last-reviewed: 2021-08-17
thoughts:
  rating: 8
  reviewable: false
---
```
Inline Fields: For those wanting a more natural-looking annotation, Dataview supports "inline" fields, which offer a simple Key:: Value syntax that you can embed directly in your file:
```
# Markdown Page

Basic Field:: Value
**Bold Field**:: Nice!
```
If you want to embed metadata inside sentences, or multiple fields on the same line, you can use the bracket syntax:
```
I would rate this a [rating:: 9]! It was [mood:: acceptable].
```
Implicit: Dataview annotates pages with a large amount of metadata automatically, like the day the file was created (file.cday), any associated dates (file.day), links in the file (file.outlinks), tags (file.tags), and so on.

A simple Markdown page which includes both user-defined ways to add metadata:

---
duration: 4 hours
reviewed: false
---
# Movie X

**Thoughts**:: It was decent.
**Rating**:: 6

Implicit Fields

Dataview automatically adds a large amount of metadata to each page:

file.name: The file title (a string).
file.folder: The path of the folder this file belongs to.
file.path: The full file path (a string).
file.link: A link to the file (a link).
file.size: The size (in bytes) of the file (a number).
file.ctime: The date that the file was created (a date + time).
file.cday: The date that the file was created (just a date).
file.mtime: The date that the file was last modified (a date + time).
file.mday: The date that the file was last modified (just a date).
file.tags: An array of all unique tags in the note. Subtags are broken down by each level, so #Tag/1/A will be stored in the array as [#Tag, #Tag/1, #Tag/1/A].
file.etags: An array of all explicit tags in the note; unlike file.tags, does not include subtags.
file.inlinks: An array of all incoming links to this file.
file.outlinks: An array of all outgoing links from this file.
file.aliases: An array of all aliases for the note.
file.tasks: An array of all tasks (I.e., - [ ] blah blah blah) in this file.

If the file has a date inside its title (of form yyyy-mm-dd or yyyymmdd), or has a Date field/inline field, it also has the following attributes:

file.day: An explicit date associated with the file.

Tasks

You can also annotate your tasks (I.e., lines of the form - [ ] blah blah blah) with metadata using inline field syntax:

- [ ] Hello, this is some [metadata:: value]!
- [X] I finished this on [completion::2021-08-15].

Field Shorthands

For supporting "common use cases", Dataview understands a few shorthands for common data you may want to annotate task with:

Syntax

Due Date: 🗓️YYYY-MM-DD
Completed Date: ✅YYYY-MM-DD
Created Date: ➕YYYY-MM-DD

Example

Do this saturday 🗓️2021-08-29.
Completed last saturday ✅2021-08-22.
I made this on ➕1990-06-14.

Note that, if you do not like emojis, you can still annotate these fields textually ([due:: ], [created:: ], [completion:: ]).

Implicit Fields

As with pages, Dataview adds a number of implicit fields to each task:

Tasks inherit all fields from their parent page - so if you have a rating field in your page, you can also access it on your task.
completed: Whether or not this specific task has been completed; this does not consider the completion/non-completion of any child tasks.
fullyCompleted: Whether or not this task and all of its subtasks are completed.
text: The text of this task.
line: The line this task shows up on.
path: The full path of the file this task is in.
section: A link to the section this task is contained in.
link: A link to the closest linkable block near this task; useful for making links which go to the task.
subtasks: Any subtasks of this task.
real: If true, this is a real task; otherwise, it is a list element above/below a task.
completion: The date a task was completed. If not annotated, will default to file modified time.
due: The date a task is due, if it has one.
created: The date a task was created. If not annotated, defaults to file creation time.
annotated: True if the task has any custom annotations, and false otherwise.

Field Types

All fields in dataview have a type, which determines how dataview will render, sort, and operate on that field. Dataview understands several distinct field types to cover common use cases:

Text: The default catch-all. If a field doesn't match a more specific type, it is just plain text.
```
Example:: This is some normal text.
```

Number: Numbers like '6' and '3.6'.

Example:: 6
Example:: 2.4
Example:: -80

Boolean: true/false, as the programming concept.
```
Example:: true
Example:: false
```
Date: ISO8601 dates of the general form YYYY-MM[-DDTHH:mm:ss.nnn+ZZ]. Everything after the month is optional.
```
Example:: 2021-04-18
Example:: 2021-04-18T04:19:35.000
Example:: 2021-04-18T04:19:35.000+06:30
```
Duration: Durations of the form <time> <unit>, like 6 hours or 4 minutes. Common english abbreviations like 6hrs or 2m are accepted. You can specify multiple units using an optional comma separator: 6 hours, 4 minutes or 6hr4min.
```
Example:: 7 hours
Example:: 4min
Example:: 16 days
Example:: 9 years, 8 months, 4 days, 16 hours, 2 minutes
Example:: 9 yrs 8 min
```
Link: Plain Obsidian links like [[Page]] or [[Page|Page Display]].
- If you reference a link in frontmatter, you need to quote it, as so: key: "[[Link]]". This is default Obsidian-supported behavior.
```
Example:: [[A Page]]
Example:: [[Some Other Page|Render Text]]
```
List: Lists of other dataview fields. In YAML, these are defined as normal YAML lists; for inline fields, they are just comma-separated lists.
```
Example:: 1, 2, 3
Example:: "yes", "or", "no"
```
Object: A map of name to dataview field. These can only be defined in YAML frontmatter, using the normal YAML object syntax:
```
field:
  value1: 1
  value2: 2
  ...
```