0
# Factory Functions
1

2
Convenient factory functions for creating Jackson ObjectMappers and JsonMappers with Kotlin support enabled by default.
3

4
## Capabilities
5

6
### Jackson ObjectMapper Factory
7

8
Create ObjectMapper instances with Kotlin module pre-registered for immediate use with Kotlin classes.
9

10
```kotlin { .api }
11
/**
12
 * Create an ObjectMapper with Kotlin module registered
13
 * @return ObjectMapper configured for Kotlin support
14
 */
15
fun jacksonObjectMapper(): ObjectMapper
16

17
/**
18
 * Create an ObjectMapper with custom Kotlin module configuration
19
 * @param initializer Lambda for configuring KotlinModule.Builder
20
 * @return ObjectMapper configured with custom Kotlin settings
21
 */
22
fun jacksonObjectMapper(initializer: KotlinModule.Builder.() -> Unit): ObjectMapper
23
```
24

25
**Usage Examples:**
26

27
```kotlin
28
import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
29
import com.fasterxml.jackson.module.kotlin.KotlinFeature
30

31
// Simple mapper with default Kotlin support
32
val mapper = jacksonObjectMapper()
33

34
// Mapper with custom Kotlin configuration
35
val customMapper = jacksonObjectMapper {
36
    enable(KotlinFeature.NullToEmptyCollection)
37
    enable(KotlinFeature.SingletonSupport)
38
    withReflectionCacheSize(1024)
39
}
40

41
data class User(val name: String, val age: Int)
42
val user = User("Alice", 30)
43
val json = mapper.writeValueAsString(user)
44
```
45

46
### JsonMapper Builder Factory
47

48
Create JsonMapper.Builder instances with Kotlin module pre-added for fluent configuration.
49

50
```kotlin { .api }
51
/**
52
 * Create a JsonMapper.Builder with Kotlin module added
53
 * @return JsonMapper.Builder configured for Kotlin support
54
 */
55
fun jacksonMapperBuilder(): JsonMapper.Builder
56

57
/**
58
 * Create a JsonMapper.Builder with custom Kotlin module configuration
59
 * @param initializer Lambda for configuring KotlinModule.Builder
60
 * @return JsonMapper.Builder configured with custom Kotlin settings
61
 */
62
fun jacksonMapperBuilder(initializer: KotlinModule.Builder.() -> Unit): JsonMapper.Builder
63
```
64

65
**Usage Examples:**
66

67
```kotlin
68
import com.fasterxml.jackson.module.kotlin.jacksonMapperBuilder
69
import com.fasterxml.jackson.module.kotlin.KotlinFeature
70

71
// Simple builder with default Kotlin support
72
val mapper = jacksonMapperBuilder().build()
73

74
// Builder with custom Kotlin configuration and other Jackson features
75
val customMapper = jacksonMapperBuilder {
76
    enable(KotlinFeature.StrictNullChecks)
77
    enable(KotlinFeature.NullIsSameAsDefault)
78
}
79
    .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
80
    .build()
81
```
82

83
### JsonMapper Factory
84

85
Create JsonMapper instances directly with optional configuration.
86

87
```kotlin { .api }
88
/**
89
 * Create a JsonMapper with optional configuration
90
 * @param initializer Lambda for configuring JsonMapper.Builder
91
 * @return JsonMapper instance
92
 */
93
fun jsonMapper(initializer: JsonMapper.Builder.() -> Unit = {}): JsonMapper
94
```
95

96
**Usage Examples:**
97

98
```kotlin
99
import com.fasterxml.jackson.module.kotlin.jsonMapper
100
import com.fasterxml.jackson.module.kotlin.kotlinModule
101
import com.fasterxml.jackson.module.kotlin.KotlinFeature
102

103
// Simple JsonMapper
104
val mapper = jsonMapper {
105
    addModule(kotlinModule())
106
}
107

108
// JsonMapper with custom Kotlin and Jackson configuration
109
val advancedMapper = jsonMapper {
110
    addModule(kotlinModule {
111
        enable(KotlinFeature.SingletonSupport)
112
        enable(KotlinFeature.UseJavaDurationConversion)
113
    })
114
    configure(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL, true)
115
}
116
```
117

118
### KotlinModule Factory
119

120
Create KotlinModule instances with optional configuration for manual registration.
121

122
```kotlin { .api }
123
/**
124
 * Create a KotlinModule with optional configuration
125
 * @param initializer Lambda for configuring KotlinModule.Builder
126
 * @return KotlinModule instance
127
 */
128
fun kotlinModule(initializer: KotlinModule.Builder.() -> Unit = {}): KotlinModule
129
```
130

131
**Usage Examples:**
132

133
```kotlin
134
import com.fasterxml.jackson.module.kotlin.kotlinModule
135
import com.fasterxml.jackson.module.kotlin.KotlinFeature
136
import com.fasterxml.jackson.databind.ObjectMapper
137

138
// Create module for manual registration
139
val module = kotlinModule {
140
    enable(KotlinFeature.NullToEmptyCollection)
141
    enable(KotlinFeature.NullToEmptyMap)
142
    withReflectionCacheSize(2048)
143
}
144

145
val mapper = ObjectMapper().registerModule(module)
146
```
147

148
### Registration Extensions
149

150
Extension functions for adding Kotlin support to existing ObjectMapper instances.
151

152
```kotlin { .api }
153
/**
154
 * Register KotlinModule with an existing ObjectMapper
155
 * @return The same ObjectMapper instance for method chaining
156
 */
157
fun ObjectMapper.registerKotlinModule(): ObjectMapper
158

159
/**
160
 * Register KotlinModule with custom configuration to an existing ObjectMapper
161
 * @param initializer Lambda for configuring KotlinModule.Builder
162
 * @return The same ObjectMapper instance for method chaining
163
 */
164
fun ObjectMapper.registerKotlinModule(initializer: KotlinModule.Builder.() -> Unit): ObjectMapper
165
```
166

167
**Usage Examples:**
168

169
```kotlin
170
import com.fasterxml.jackson.databind.ObjectMapper
171
import com.fasterxml.jackson.module.kotlin.registerKotlinModule
172
import com.fasterxml.jackson.module.kotlin.KotlinFeature
173

174
// Add Kotlin support to existing mapper
175
val existingMapper = ObjectMapper()
176
existingMapper.registerKotlinModule()
177

178
// Add Kotlin support with custom configuration
179
val customMapper = ObjectMapper()
180
    .registerKotlinModule {
181
        enable(KotlinFeature.SingletonSupport)
182
        enable(KotlinFeature.NewStrictNullChecks)
183
    }
184
    .configure(DeserializationFeature.FAIL_ON_NULL_FOR_PRIMITIVES, true)
185
```
186

187
## Integration Patterns
188

189
### Spring Boot Integration
190

191
```kotlin
192
import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
193
import com.fasterxml.jackson.module.kotlin.KotlinFeature
194
import org.springframework.context.annotation.Bean
195
import org.springframework.context.annotation.Configuration
196

197
@Configuration
198
class JacksonConfig {
199
    
200
    @Bean
201
    fun objectMapper() = jacksonObjectMapper {
202
        enable(KotlinFeature.NullToEmptyCollection)
203
        enable(KotlinFeature.SingletonSupport)
204
    }
205
}
206
```
207

208
### Ktor Integration
209

210
```kotlin
211
import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
212
import io.ktor.serialization.jackson.*
213
import io.ktor.server.application.*
214
import io.ktor.server.plugins.contentnegotiation.*
215

216
fun Application.configureSerialization() {
217
    install(ContentNegotiation) {
218
        jackson {
219
            registerKotlinModule()
220
        }
221
    }
222
}
223
```