# Core concepts

# Schemas

Schemas are the core building blocks within the content field. A schema is identified by a qualifier and consists of multiple fields. The field ships with two built-in schema types:

• Template schemas are defined by a twig template.
• Structure schemas are defined by a yaml file.

# Qualifiers

A qualifier is the internal name of a schema. It consits of the schema type and schema name separated by a colon like this:

{SCHEMA_TYPE}:{SCHEMA_NAME}

The schema type can be omitted. When no type is specified the content field tries to find:

1. A local schema / structure with the given schema name.
2. A template schema with the given schema name.

# Qualifier matching

On multiple occasions qualifiers will be matched against a pattern, e.g.

• When specifying qualifiers as field attributes like the schemas attribute on the instance and instances fields.
• When using certain utility functions like matchesQualifier on schemas or findInstances, hasNextSibling, hasParentInstance or hasPreviousSibling on instances.

In all those instances you might specify your pattern in one of the following ways:

• As a complete, absolute qualifier with type and name:

  {% if instance.schema.matchesQualifier('template:path/to/template') %}
    ...
  {% endif %}
  

• A partial qualifier, will be resolved to a local or template schema:

  {% if instance.schema.matchesQualifier('path/to/template') %}
    ...
  {% endif %}
  

• A wildcard qualifier:

  {% if instance.schema.matchesQualifier('template:path/to/*') %}
    ...
  {% endif %}
  

• An array of patterns:

  {% if instance.schema.matchesQualifier([
    'template:path/to/template-a',
    'template:path/to/template-b',
    'template:path/other/*',
  ]) %}
    ...
  {% endif %}
  

# Fields

Fields define the properties a schema consists of, they are used to generate the interface when editing instances in the control panel. For a complete list of available fields types, see fields.

# Instances

A populated model that contains the actual values defiend by the fields of a schema is called an instance. Instances are JSON documents that are stored to your database.