Data Model XML Format

This document provides a detailed specification for the XML syntax used to define a Data Model in JourneyApps.

Example Data Model

<?xml version="1.0" encoding="UTF-8"?>
<schema>
    <object name="asset" label="Asset">
        <attribute name="make" label="Make" type="string" spec="text.name"/>
        <attribute name="model" label="Model" type="string" spec="text.name"/>
        <attribute name="serial_number" label="Serial Number" type="string" spec="number"/>
        <attribute name="description" label="Description" type="string" />
        <attribute name="picture" label="Picture" type="attachment" media="image/jpeg"/>
        <attribute name="condition" label="Condition" type="enum">
            <option>Good</option>
            <option>Ok</option>
            <option>Bad</option>
        </attribute>

        <belongs_to type="building" />

        <display format="{make} {model} {serial_number}"/>
    </object>

    <object name="building" label="Building">
        <attribute name="name" label="Name" type="string" spec="text.name"/>

        <has_many type="asset" name="assets" />

        <display format="{name}"/>
    </object>
</schema>

object

Defines a single object type.

The following options can be specified for an object tag:

Name	Required?	Details
`name`	required	Unique identifier for this object type. Used anywhere that code needs to reference the object.
`label`	required	Human-readable label for the object. Used wherever it is displayed to an user.

Nested Tags

The following can be placed inside an object tag:

Nested Element	Details
`attribute`	An attribute (property) of the object.
`belongs_to`	Defines relationships between objects. If you are specifying a one-to-many relationship between objects, and this object type is one of the "many" objects that belongs to another object type, you need to specify a `belongs_to` for this object in the Data Model.
`has_many`	Defines relationships between objects. If you are specifying a one-to-many relationship between objects, and this object type has many objects of another object type that belong to it, you need to specify a `has_many` for this object in the Data Model.
`display`	Defines how an object should be displayed to the user by default (for example, in a list). See Format String for details on the `format` attribute.

attribute

The following options can be specified for an attribute tag:

Name	Required?	Details
`name`	required	Identifier for this attribute, unique per object type. Used anywhere that code needs to reference the object.
`label`	required	Human-readable label for this attribute. Used wherever it is displayed to an user.
`type`	required	The type of this attribute. See Attribute & Variable Types for the possible types.
`spec`	optional	Only applicable to `string` types. See Attribute & Variable Types for possible values.
`media`	optional	Only applicable to `attachment` types. See Attribute & Variable Types for possible values.
`minValue`	optional	Only applicable to `int` types. Specifies the minimum value that this attribute may have.
`maxValue`	optional	Only applicable to `int` types. Specifies the maximum value that this attribute may have.

Nested Tags

The following can be placed inside an attribute tag:

Nested Element	Details
`option`	Applicable to `enum` and `enum_set` types. Specifies a single option value.

belongs_to

Specifies that the object "belongs to" another object.

The following options can be specified for a belongs_to tag:

Name	Required?	Details
`type`	required	The name of the object type that this object belongs to.
`name`	optional	Name for the relationship. Used in code whenever this relationship needs to be accessed. Defaults to what you specified at `type`.

has_many

Specifies that the object "has many" of another object. This is the inverse of "belongs_to".

The following options can be specified for a has_many tag:

Name	Required?	Details
`type`	required	The name of the object type of which this object has many.
`name`	required	Name for the relationship. Used in code whenever this relationship needs to be accessed. Recommended value is the pluralised form of the object type name on the other side of the relationship, for example "assets".
`inverse_of`	optional	The name of the "belongs_to" reference on the other object. This is required when there are multiple relationships between the same two object types.