Following is an example of unidirectional one-to-many relationship:<\/p>\n
\r\nclass Employee {\r\n String name\r\n static hasMany = [roles: Role]\r\n}\r\n\r\nclass Role {\r\n String name\r\n}\r\n<\/pre>\nHow can we find all the employees with a particular role – “Grails Developer”?<\/p>\n
\r\nRole role = Role.findByName(\"Grails Developer\")\r\n<\/pre>\nOne way of doing this can be: <\/p>\n
\r\nEmployee.list().findAll{role in it.roles}\r\n<\/pre>\nThis is an inefficient way since, we are fetching all the records from the database every time. Also, in case we are showing paginated view of results, we will need to manage pagination ourself. <\/p>\n
A better way of this will be using createCriteria() query:<\/p>\n
\r\nList employees = Employee.createCriteria().list{\r\n roles{\r\n eq('id', role.id)\r\n }\t\r\n firstResult(20)\r\n maxResults(20)\t\r\n}\t\r\n<\/pre>\nI am wondering what will be the query in case Role.groovy is an enum.<\/p>\n
\u2013
\n~Aman Aggarwal
\naman@intelligrape.com<\/p>\n