Implement $set stage dsl

core/src/main/kotlin/com/github/inflab/spring/data/mongodb/core/aggregation/AggregationDsl.kt

@@ -298,6 +298,16 @@ class AggregationDsl {
         operations += AddFieldsStageDsl().apply(configuration).get()
     }
 
+    /**
+     * Configures a stage that set in documents.
+     *
+     * @param configuration The configuration block for the [SetStageDsl].
+     * @see <a href="https://docs.mongodb.com/manual/reference/operator/aggregation/set">$set (aggregation)</a>
+     */
+    fun set(configuration: SetStageDsl.() -> Unit) {
+        operations += SetStageDsl().apply(configuration).get()
+    }
+
     /**
      * Builds the [Aggregation] using the configured [AggregationOperation]s.
      *

core/src/main/kotlin/com/github/inflab/spring/data/mongodb/core/aggregation/SetStageDsl.kt

@@ -0,0 +1,96 @@
+package com.github.inflab.spring.data.mongodb.core.aggregation
+
+import com.github.inflab.spring.data.mongodb.core.aggregation.expression.AggregationExpressionDsl
+import com.github.inflab.spring.data.mongodb.core.annotation.AggregationMarker
+import com.github.inflab.spring.data.mongodb.core.extension.toDotPath
+import org.springframework.data.mongodb.core.aggregation.AggregationExpression
+import org.springframework.data.mongodb.core.aggregation.SetOperation
+import kotlin.reflect.KProperty
+
+/**
+ * A Kotlin DSL to configure $set stage using idiomatic Kotlin code.
+ *
+ * @author username1103
+ * @since 1.0
+ * @see <a href="https://www.mongodb.com/docs/manual/reference/operator/aggregation/set">$set (aggregation)</a>
+ */
+@AggregationMarker
+class SetStageDsl {
+    private val builder = SetOperation.builder()
+
+    private var operation: SetOperation? = null
+
+    /**
+     * Adds new fields to documents with aggregation expression.
+     *
+     * @param configuration The configuration block where you can use DSL to define aggregation expression.
+     */
+    infix fun String.set(configuration: AggregationExpressionDsl.() -> AggregationExpression) {
+        operation = builder.set(this).toValue(AggregationExpressionDsl().configuration())
+    }
+
+    /**
+     * Adds new fields to documents from a field.
+     *
+     * @param path The path of the field to contain value to be added.
+     */
+    infix fun String.set(path: KProperty<Any?>) {
+        operation = builder.set(this).toValue("${'$'}${path.toDotPath()}")
+    }
+
+    /**
+     * Adds new fields to documents with a value.
+     *
+     * @param value The value of the field to add.
+     */
+    infix fun String.set(value: Any?) {
+        operation = builder.set(this).toValue(value)
+    }
+
+    /**
+     * Adds new fields to documents from a field.
+     *
+     * @param fieldPath The path of the field to contain value to be added.
+     */
+    infix fun String.setByField(fieldPath: String) {
+        operation = builder.set(this).toValue("$$fieldPath")
+    }
+
+    /**
+     * Adds new fields to documents with aggregation expression.
+     *
+     * @param configuration The configuration block where you can use DSL to define aggregation expression.
+     */
+    infix fun KProperty<Any?>.set(configuration: AggregationExpressionDsl.() -> AggregationExpression) {
+        operation = builder.set(this.toDotPath()).toValue(AggregationExpressionDsl().configuration())
+    }
+
+    /**
+     * Adds new fields to documents from a field.
+     *
+     * @param path The path of the field to contain value to be added.
+     */
+    infix fun KProperty<Any?>.set(path: KProperty<Any?>) {
+        operation = builder.set(this.toDotPath()).toValue("${'$'}${path.toDotPath()}")
+    }
+
+    /**
+     * Adds new fields to documents with a value.
+     *
+     * @param value The value of the field to add.
+     */
+    infix fun KProperty<Any?>.set(value: Any?) {
+        operation = builder.set(this.toDotPath()).toValue(value)
+    }
+
+    /**
+     * Adds new fields to documents from a field.
+     *
+     * @param fieldPath The path of the field to contain value to be added.
+     */
+    infix fun KProperty<Any?>.setByField(fieldPath: String) {
+        operation = builder.set(this.toDotPath()).toValue("$$fieldPath")
+    }
+
+    internal fun get() = checkNotNull(operation) { "Set operation must not be null!" }
+}

core/src/test/kotlin/com/github/inflab/spring/data/mongodb/core/aggregation/SetStageDslTest.kt

@@ -0,0 +1,203 @@
+package com.github.inflab.spring.data.mongodb.core.aggregation
+
+import com.github.inflab.spring.data.mongodb.core.util.shouldBeJson
+import io.kotest.core.spec.style.FreeSpec
+
+class SetStageDslTest : FreeSpec({
+    fun set(configuration: SetStageDsl.() -> Unit): SetStageDsl =
+        SetStageDsl().apply(configuration)
+
+    "set" - {
+        "should set field with path" {
+            // given
+            data class Test(val targetPath: Int)
+            val stage = set {
+                "a" set Test::targetPath
+            }
+
+            // when
+            val result = stage.get()
+
+            // then
+            result.shouldBeJson(
+                """
+                {
+                  "${'$'}set": {
+                    "a": "${'$'}targetPath"
+                  }
+                }
+                """.trimIndent(),
+            )
+        }
+
+        "should set field path with path" {
+            // given
+            data class Test(val sourcePath: Int, val targetPath: Int)
+            val stage = set {
+                Test::targetPath set Test::sourcePath
+            }
+
+            // when
+            val result = stage.get()
+
+            // then
+            result.shouldBeJson(
+                """
+                {
+                  "${'$'}set": {
+                    "targetPath": "${'$'}sourcePath"
+                  }
+                }
+                """.trimIndent(),
+            )
+        }
+
+        "should set field with aggregation expression" {
+            // given
+            data class Test(val targetPath: Int)
+            val stage = set {
+                "a" set {
+                    add { of(1) and 2 and Test::targetPath }
+                }
+            }
+
+            // when
+            val result = stage.get()
+
+            // then
+            result.shouldBeJson(
+                """
+                {
+                  "${'$'}set": {
+                    "a": {
+                      "${'$'}add": [
+                        1,
+                        2,
+                        "${'$'}targetPath"
+                      ]
+                    }
+                  }
+                }
+                """.trimIndent(),
+            )
+        }
+
+        "should set field path with aggregation expression" {
+            // given
+            data class Test(val sourcePath: Int, val targetPath: Int)
+            val stage = set {
+                Test::targetPath set {
+                    add { of(1) and 2 and Test::sourcePath }
+                }
+            }
+
+            // when
+            val result = stage.get()
+
+            // then
+            result.shouldBeJson(
+                """
+                {
+                  "${'$'}set": {
+                    "targetPath": {
+                      "${'$'}add": [
+                        1,
+                        2,
+                        "${'$'}sourcePath"
+                      ]
+                    }
+                  }
+                }
+                """.trimIndent(),
+            )
+        }
+
+        "should set field with value" {
+            // given
+            val stage = set {
+                "a" set 1
+            }
+
+            // when
+            val result = stage.get()
+
+            // then
+            result.shouldBeJson(
+                """
+                {
+                  "${'$'}set": {
+                    "a": 1
+                  }
+                }
+                """.trimIndent(),
+            )
+        }
+
+        "should set field path with value" {
+            // given
+            data class Test(val targetPath: Int)
+            val stage = set {
+                Test::targetPath set 1
+            }
+
+            // when
+            val result = stage.get()
+
+            // then
+            result.shouldBeJson(
+                """
+                {
+                  "${'$'}set": {
+                    "targetPath": 1
+                  }
+                }
+                """.trimIndent(),
+            )
+        }
+    }
+
+    "setByField" - {
+        "should set field with value of other field" {
+            // given
+            val stage = set {
+                "a" setByField "b"
+            }
+
+            // when
+            val result = stage.get()
+
+            // then
+            result.shouldBeJson(
+                """
+                {
+                  "${'$'}set": {
+                    "a": "${'$'}b"
+                  }
+                }
+                """.trimIndent(),
+            )
+        }
+
+        "should set field path with value of other field" {
+            // given
+            data class Test(val targetPath: Int)
+            val stage = set {
+                Test::targetPath setByField "b"
+            }
+
+            // when
+            val result = stage.get()
+
+            // then
+            result.shouldBeJson(
+                """
+                {
+                  "${'$'}set": {
+                    "targetPath": "${'$'}b"
+                  }
+                }
+                """.trimIndent(),
+            )
+        }
+    }
+})