Grails - CRUD

8/3/2019 Grails - CRUD

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Grails

Creating CRUD applications


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Example Application:

Books Wish List Book is added to the wish list

Book from the wish list can be bought or

refused Simple CRUD application with only one

domain object


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What will be presented

Domain object

Controller

View (gsp groovy server pages)


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What is Domain Object?

Represents part of the domain problem

Mapped to database

Database is automatically generated Groovy class extended with useful methods

GORM Grails Object Relations Mapping


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Book as Domain Object


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What to Notice?

Domain object is mapped to database table

Properties are mapped to table columns

Constraints are used to validate input(minSize, maxSize, inList, blank,)

Error messages due the constraints areconfigurable according to convention

Domain class is by convention created indirectory domain


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How to Create Domain Class?

Generate Grails application with:grails create-app

Create domain class with:grails create-domain-class

Code the domain class


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What is Controller?

Controller handle requests and createsresponses

Controller is request based

Each request is mapped with closure

If not specified differently, closure incontroller is mapped to view (gsp)


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Book Controller

Following closures are automatically generated fordomain class controller:

y index displays list of all domain objects

y list displays list of all domain objectsy show shows details of the domain object

y delete deletes the domain object

y edit opens page for editing of domain object

y update updates changes made to domain objecty create opens page for domain object creation

y save saves the domain object


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What to Notice?

Generated closures are for CRUD operations

Use of dynamic methods on domain objects(save, hasErrors, get, list)

Renderingand redirecting

Name of the controller by convention is:Controller

Controller is by convention created indirectory controllers


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How to Generate Controller for

Domain Class? Generate controller using script:grails generate-controller

Make changes to controller if necessary (forsimple CRUD applications you can leave itas is)


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What is View (gsp)?

In Grails views are gsp groovy serverpages

gsp is similar to jsp orasp but much more

flexible

Data models provide data to view

gsp page consists of markup (html) andgsp

tags (e.g.g:remoteLink,g:paginate,)


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Book Views

Following views are automatically generatedfor domain class:

y create

y edit

y list

y show


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What to Notice?

Generated views are for CRUD operations

Accessing to model data with ${..} construct

Views are by convention generated in thedirectory views/

Actually functionality and layout of page isgood out of the box and for internalapplication can be reused withoutmodifications


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How to Generate Views for Domain

Class Generate views using script:

grails generate-views

Make changes to views if necessary (forsimple CRUD applications you can leave itas is)


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And for the end

Questions?

Oh, yes you can run the application withgrails run-app

And access application onhttp://localhost:8080/

Grails - CRUD

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