Kotlin DSL
Kotlin DSL based usage of the ShapeShift library.
Basic Mapping
We start by defining two classes, our source class SimpleEntity
and our destination class SimpleEntityDisplay
.
We can now create a simple mapper. In this example, we want to map the name
and description
fields of SimpleEntity
to the name
and description
fields of the SimpleEntityDisplay
class, but not the privateData
field.
To instantiate ShapeShift
we use the ShapeShiftBuilder
and register our mapper:
All that's left is to map the SimpleEntity
instance to the SimpleEntityDisplay
class.
Mapping Fields
In the example above we did basic mapping between fields. But what if we want to map from/to deep fields of child classes?
In order to access child classes we can use the ..
operator. Let's look at the following example:
We want to map the value
field in Child
class inside the From
class to the childValue
field in the To
class. We will create a mapper with the ..
operator.
The ..
operator is supported in both source and destination fields, it also supports multi level depth.
To access the grand child field we just use the ..
operator twice.
Transformers
Field transformers are a way to transform a field from one type to another when mapping it to a destination class. More about the ins-and-outs of transformers is available here:
The withTransformer
function has 2 options to use transformers. Let's look at the following classes.
We want to map the commaDelimitedString
field to the stringList
field and change the field type from String
to List<String>
while doing so. To accomplish that we will use a transformer.
Class Transformer
Our first option is to create a transformer class, StringToListMappingTransformer
;
All we need to do to use our transformer is to pass it to the withTransformer
function.
Transformers must be registered to the ShapeShift
instance in order to be used. More info about registering transformers is available in the transformers page.
Inline Transformer
Our second option is to use an inline transformer. When we don't need to reuse a transformer we can just add its logic to the DSL.
Auto Mapping
Auto mapping is used to reduce the amount of boiler-place code required to configure mapping between two classes. More info about auto mapping is available here:
Auto mapping can be added using the autoMap
function.
autoMap
function receives the desired auto mapping strategy. It is possible to add any manual mapping to add/change mapping behavior.
Mapping Condition
Conditions are used to determine wether a field should be mapped according to certain logic. More info about conditions is available here:
Let's look at the following classes.
We want to map the name
field only if it's not null or blank. The withCondition
function has 2 options to add conditions.
Class Condition
Our first option is to create a condition class. The condition receives context with the original value of the field and checks that it is not null or blank.
We will create our mapper and add the condition.
Inline Condition
Our second option is to use an inline condition. When we don't need to reuse a condition we can just add its logic to the DSL.
Decorators
Decorators allow to add additional logic to the mapping operation. More info about conditions is available here:
Let's look at the following classes.
We want to merge the firstName
and lastName
fields to the fullName
field in addition to mapping them to their respectable fields.
Decorators can be added inline or as a separate class.
Class Decorators
To create a decorator class implement the MappingDecorator
interface.
And register it to the ShapeShift
instance.
Inline Decorators
It is also possible to add the decorator logic inline.
Object Suppliers
Due to the fact that ShapeShift uses reflection behind the scenes, destination classes need a no arg constructor. But in some cases you have no control over the destination classes and cannot modify them to add a no arg constructor. This is where Object Suppliers comes into play, you can register object suppliers to the ShapeShift instance to add your own logic for instance generation.
More info about Object Suppliers is available here:
Override Mapping Strategy
The overrideStrategy
function allows you to override the default mapping strategy configured on the ShapeShift
instance.
More info about mapping strategy is available here:
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