Define Frontmatter Schema

Schemas define the structure of your content's frontmatter—the YAML metadata at the top of each markdown file. With md0 CMS, you can create schemas using a visual interface instead of editing raw YAML.

What is a Schema?

A schema is a set of fields that define:

• What information each content file should have
• The type of each field (string, date, boolean, etc.)
• Which fields are required vs optional
• Default values for fields
• Validation rules

Creating a Schema

Access Schema Editor

1. Navigate to your collection
2. Click "Schema" or "Edit Schema"
3. You'll see the schema configuration interface

Adding Fields

Click "Add Field" and configure:

Field Name: title
Field Type: string
Required: true
Description: The post title
Default Value: (empty)

Field Types

String

Short single-line text input.

name: title
type: string
required: true
placeholder: "Enter post title"

Use for:

• Titles
• Names
• Short descriptions
• URLs
• Tags (single)

Frontmatter output:

title: "Getting Started with md0 CMS"

Text

Multi-line text area for longer content.

name: excerpt
type: text
required: false
maxLength: 300
placeholder: "Brief summary of the post"

Use for:

• Descriptions
• Excerpts
• Meta descriptions
• Summaries

Frontmatter output:

excerpt: |
  This guide will walk you through
  the basics of setting up md0 CMS.

Number

Numeric input with optional min/max validation.

name: order
type: number
required: false
min: 0
max: 100
default: 0

Use for:

• Sort order
• Reading time
• View counts
• Numeric IDs

Frontmatter output:

order: 1

Boolean

True/false toggle switch.

name: published
type: boolean
required: true
default: false

Use for:

• Published status
• Featured flags
• Enable/disable options
• Visibility toggles

Frontmatter output:

published: true
featured: false

Date

Date picker with optional time.

name: date
type: date
required: true
default: now
format: "YYYY-MM-DD"

Use for:

• Publication dates
• Last updated timestamps
• Event dates
• Scheduling

Frontmatter output:

date: 2024-01-15

DateTime

Date and time picker.

name: publishedAt
type: datetime
required: true
default: now
format: "YYYY-MM-DD HH:mm:ss"

Frontmatter output:

publishedAt: 2024-01-15 14:30:00

Array

List of items (strings, numbers, etc.).

name: tags
type: array
items: string
required: false

Use for:

• Tags
• Categories
• Authors (multiple)
• Keywords

Frontmatter output:

tags:
  - markdown
  - cms
  - github

Select

Dropdown with predefined options.

name: category
type: select
required: true
options:
  - Tutorial
  - Guide
  - News
  - Case Study

Use for:

• Categories
• Status (draft, published, archived)
• Type selection
• Priority levels

Frontmatter output:

category: Tutorial

Image

Image upload with URL storage.

name: featured_image
type: image
required: false
folder: /public/images/posts

Use for:

• Featured images
• Author avatars
• Cover photos
• Thumbnails

Frontmatter output:

featured_image: /images/posts/hero-image.jpg

Object

Nested fields for complex data.

name: author
type: object
fields:
  - name: name
    type: string
  - name: email
    type: string
  - name: avatar
    type: image

Frontmatter output:

author:
  name: "Jane Doe"
  email: "jane@example.com"
  avatar: "/images/authors/jane.jpg"

Field Options

Required Fields

Mark fields as required to ensure they're always filled:

name: title
type: string
required: true # Content cannot be saved without this field

Default Values

Set default values for new content:

name: published
type: boolean
default: false # New posts start as drafts

name: author
type: string
default: "Admin"

Field Validation

String Validation

name: slug
type: string
pattern: "^[a-z0-9-]+$" # Only lowercase letters, numbers, hyphens
minLength: 3
maxLength: 100

Number Validation

name: rating
type: number
min: 1
max: 5

Array Validation

name: tags
type: array
minItems: 1
maxItems: 5

Field Descriptions

Add helpful hints for content editors:

name: excerpt
type: text
description: "A brief summary shown in post listings. Aim for 2-3 sentences."

Schema Examples

Blog Post Schema

fields:
  - name: title
    type: string
    required: true

  - name: date
    type: date
    required: true
    default: now

  - name: excerpt
    type: text
    required: true
    maxLength: 200

  - name: author
    type: string
    required: true
    default: "Admin"

  - name: tags
    type: array
    items: string

  - name: category
    type: select
    options:
      - Tutorial
      - Guide
      - News

  - name: featured_image
    type: image

  - name: published
    type: boolean
    default: false

Documentation Schema

fields:
  - name: title
    type: string
    required: true

  - name: description
    type: text
    required: true

  - name: order
    type: number
    default: 0
    description: "Order in sidebar navigation"

  - name: category
    type: select
    options:
      - Getting Started
      - Guides
      - API Reference

  - name: last_updated
    type: date
    default: now

Product Schema

fields:
  - name: name
    type: string
    required: true

  - name: description
    type: text
    required: true

  - name: price
    type: number
    required: true
    min: 0

  - name: images
    type: array
    items: image

  - name: in_stock
    type: boolean
    default: true

  - name: category
    type: select
    options:
      - Electronics
      - Clothing
      - Books

Advanced Schema Features

Conditional Fields

Show fields based on other field values:

- name: post_type
  type: select
  options:
    - Article
    - Video

- name: video_url
  type: string
  condition:
    field: post_type
    equals: Video

Field Groups

Organize related fields:

- name: seo
  type: object
  fields:
    - name: meta_title
      type: string
    - name: meta_description
      type: text
    - name: keywords
      type: array
      items: string

Schema Best Practices

Keep It Simple

• Start with essential fields only
• Add fields as needed
• Avoid over-complicating schemas
• Consider editor experience

Use Appropriate Types

• Use select for limited options
• Use boolean instead of yes/no strings
• Use date for dates, not strings
• Use number for numeric values

Provide Clear Labels

# Good
name: featured_image
label: "Featured Image"
description: "Main image shown at the top of the post"

# Bad
name: img1
label: "img1"

Set Sensible Defaults

# For blog posts
published: false # Draft by default
date: now # Current date
author: "Admin" # Default author

Validate Input

Use validation to prevent errors:

# Slug validation
pattern: "^[a-z0-9-]+$"

# Email validation
pattern: "^[^@]+@[^@]+\.[^@]+$"

# URL validation
pattern: "^https?://"

Editing Schemas

Modifying Existing Schemas

1. Go to Collection > Schema
2. Edit, add, or remove fields
3. Save changes

Note: Changing schemas doesn't automatically update existing content—only new or edited content will use the new schema.

Migrating Content

When you change schemas significantly:

1. Export existing content
2. Update schema
3. Batch update content if needed
4. Test with sample content

Schema Validation

md0 CMS validates content against your schema:

• Required fields: Must be filled
• Type validation: Values must match field type
• Pattern validation: Strings must match regex
• Range validation: Numbers must be within min/max

Validation errors appear in the editor before saving.

Troubleshooting

Frontmatter Not Parsing

Check:

• YAML syntax is correct
• Indentation is consistent
• Quotes are balanced
• Special characters are escaped

Fields Not Appearing

Check:

• Schema is saved
• Field name matches frontmatter key
• Field type is appropriate
• Cache is cleared

Validation Errors

Check:

• Required fields are filled
• Values match field types
• Pattern matches regex
• Numbers are within range

Next Steps

After defining your schema:

1. Create Content using your schema
2. Configure Collections for advanced patterns
3. Integrate with Your Site to use the content

Related Documentation

• Collection Patterns - Advanced collection configuration
• Schema Configuration - Detailed schema options
• Markdown Editing - Using the editor