Generating MOLGENIS from scratch

We will generate a new MOLGENIS by the example of a simple Address Book application:

a simple database having “Contacts” entities that each can have zero or more “Addresses”:

1. Create the data model XML

Create a new xml file ‘addressbook_db.xml’ in the root of you application. This file will contain the MOLGENIS model. Use the following template:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE molgenis PUBLIC "MOLGENIS 1.0" "http://molgenis.sourceforge.net/dtd/molgenis_v_1_0.dtd">
<molgenis name="addressbook">

</molgenis>

2. Add a “Contact” data type.

<molgenis name="addressbook">
  <entity name="Contact">
                
  </entity>
</molgenis>

3. Add properties to the “Contact” data type.

• A unique, automatic numeric identifier field that MOLGENIS will use to refer contacts.

  <field name="contact_id" type="autoid"/>
  

• A required and unique string field ‘displayname’ to have a unique label to find Contacts by. Note that if you provide no ‘type’ then type=”string” is implied.

  <field name="displayname" unique="true"/>
  

• Optional (‘nillable’) string fields for firstname, lastname and midinitials:

  <field name="firstname" nillable="true"/>
  <field name="midinitials" nillable="true"/>
  <field name="lastname" nillable="true"/>
  

• An optional field of type date for birthday:

  <field name="birthday" type="date" nillable="true"/>
  

4. Similarly create a “Address” data type (to keep it simple we only do phone numbers):

• Entity address

  !xml
  <entity name="Address">
  

• A unique, automatic numeric identifier field that MOLGENIS will use to refer addresses.

  !xml
  <field name="address_id" type="autoid"/>
  

• Add the phone number field:

  <field name="phone"/>
  

• Add a field where the user can choose from an enumeration of options whether the address is ‘home’,’work’,or ‘mobile’:

  <field name="address_type" type="enum" enum_options="[home,work,mobile]"/>
  

5. Finally we need to link the Addresses to each Contact.

• In the Address entity create a ForeignKey? reference to Contact

  <field name="contact" type="xref"     
           xref_field="Contact.contact_id"       
           xref_label="displayname"/>
  </entity>
  

Note that the xref_field refers to unique field ‘contact_id’ in entity ‘Contact’. The xref_label attribute indicates that we want to view references to Contact by ‘displayname’ name instead of the numeric id.

Use of a meaningless numeric ‘id’ next to a meaningful ‘label’ enables us to change the ‘displayname’ name on Contact without the problem of also having to change this on each Address that refers to this contact.