add toDataFrame pojo-like class check

core/generated-sources/src/main/kotlin/org/jetbrains/kotlinx/dataframe/impl/api/toDataFrame.kt

@@ -75,11 +75,13 @@ internal val KClass<*>.isValueType: Boolean
             this.isArray
 
 /**
- * Checks if `KClass` has properties.
+ * Checks if `KClass` has public properties / getter functions (for pojo-like classes).
  */
 @PublishedApi
 internal val KClass<*>.hasProperties: Boolean
-    get() = this.memberProperties.isNotEmpty()
+    get() = this.memberProperties.any { it.visibility == KVisibility.PUBLIC } ||
+        // check pojo-like classes
+        this.memberFunctions.any { it.visibility == KVisibility.PUBLIC && it.isGetterLike() }
 
 internal class CreateDataFrameDslImpl<T>(
     override val source: Iterable<T>,

core/generated-sources/src/test/kotlin/org/jetbrains/kotlinx/dataframe/api/toDataFrame.kt

@@ -398,6 +398,14 @@ class CreateDataFrameTests {
         enums.toDataFrame() shouldBe dataFrameOf("value")(*enums.toTypedArray())
     }
 
+    class NoPublicPropsClass(private val a: Int, private val b: String)
+
+    @Test
+    fun `should convert class with no public properties to DataFrame with value column`() {
+        val objs: List<NoPublicPropsClass> = listOf(NoPublicPropsClass(1, "a"), NoPublicPropsClass(2, "b"))
+        objs.toDataFrame() shouldBe dataFrameOf("value")(*objs.toTypedArray())
+    }
+
     interface Animal {
         fun say(): String
     }

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/impl/api/toDataFrame.kt

@@ -75,11 +75,13 @@ internal val KClass<*>.isValueType: Boolean
             this.isArray
 
 /**
- * Checks if `KClass` has properties.
+ * Checks if `KClass` has public properties / getter functions (for pojo-like classes).
  */
 @PublishedApi
 internal val KClass<*>.hasProperties: Boolean
-    get() = this.memberProperties.isNotEmpty()
+    get() = this.memberProperties.any { it.visibility == KVisibility.PUBLIC } ||
+        // check pojo-like classes
+        this.memberFunctions.any { it.visibility == KVisibility.PUBLIC && it.isGetterLike() }
 
 internal class CreateDataFrameDslImpl<T>(
     override val source: Iterable<T>,

core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/api/toDataFrame.kt

@@ -398,6 +398,14 @@ class CreateDataFrameTests {
         enums.toDataFrame() shouldBe dataFrameOf("value")(*enums.toTypedArray())
     }
 
+    class NoPublicPropsClass(private val a: Int, private val b: String)
+
+    @Test
+    fun `should convert class with no public properties to DataFrame with value column`() {
+        val objs: List<NoPublicPropsClass> = listOf(NoPublicPropsClass(1, "a"), NoPublicPropsClass(2, "b"))
+        objs.toDataFrame() shouldBe dataFrameOf("value")(*objs.toTypedArray())
+    }
+
     interface Animal {
         fun say(): String
     }

plugins/kotlin-dataframe/src/org/jetbrains/kotlinx/dataframe/plugin/impl/api/toDataFrame.kt

@@ -23,6 +23,7 @@ import org.jetbrains.kotlin.fir.scopes.collectAllProperties
 import org.jetbrains.kotlin.fir.scopes.unsubstitutedScope
 import org.jetbrains.kotlin.fir.symbols.SymbolInternals
 import org.jetbrains.kotlin.fir.symbols.impl.FirClassSymbol
+import org.jetbrains.kotlin.fir.symbols.impl.FirNamedFunctionSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirPropertySymbol
 import org.jetbrains.kotlin.fir.types.ConeClassLikeType
 import org.jetbrains.kotlin.fir.types.ConeFlexibleType
@@ -224,12 +225,27 @@ internal fun KotlinTypeFacade.toDataFrame(
                 Names.TEMPORAL_AMOUNT_CLASS_ID.constructClassLikeType(emptyArray(), isNullable = true), session
             )
 
+    fun FirNamedFunctionSymbol.isGetterLike(): Boolean {
+        val functionName = this.name.asString()
+        return (functionName.startsWith("get") || functionName.startsWith("is")) &&
+            this.valueParameterSymbols.isEmpty() &&
+            this.typeParameterSymbols.isEmpty()
+    }
+
     fun ConeKotlinType.hasProperties(): Boolean {
         val symbol = this.toRegularClassSymbol(session) as? FirClassSymbol<*> ?: return false
-        val scope = symbol.unsubstitutedScope(session, ScopeSession(), withForcedTypeCalculator = false, memberRequiredPhase = null)
-        return scope.collectAllProperties().isNotEmpty()
+        val scope = symbol.unsubstitutedScope(
+            session,
+            ScopeSession(),
+            withForcedTypeCalculator = false,
+            memberRequiredPhase = null
+        )
+
+        return scope.collectAllProperties().any { it.visibility == Visibilities.Public } ||
+            scope.collectAllFunctions().any { it.visibility == Visibilities.Public && it.isGetterLike() }
     }
 
+
     val excludes =
         traverseConfiguration.excludeProperties.mapNotNullTo(mutableSetOf()) { it.calleeReference.toResolvedPropertySymbol() }
     val excludedClasses = traverseConfiguration.excludeClasses.mapTo(mutableSetOf()) { it.argument.resolvedType }

plugins/kotlin-dataframe/testData/box/toDataFrameNoPublicPropertiesType.kt

@@ -0,0 +1,13 @@
+import org.jetbrains.kotlinx.dataframe.*
+import org.jetbrains.kotlinx.dataframe.api.*
+
+class NoPublicPropsClass(private val a: Int, private val b: String)
+
+fun box(): String {
+    val objs: List<NoPublicPropsClass> = listOf(NoPublicPropsClass(1, "a"), NoPublicPropsClass(2, "b"))
+    val df = objs.toDataFrame()
+
+    val objsCol: DataColumn<NoPublicPropsClass> = df.value
+
+    return "OK"
+}

plugins/kotlin-dataframe/tests-gen/org/jetbrains/kotlin/fir/dataframe/DataFrameBlackBoxCodegenTestGenerated.java

@@ -562,6 +562,12 @@ public void testToDataFrameNoPropertiesType() {
     runTest("testData/box/toDataFrameNoPropertiesType.kt");
   }
 
+  @Test
+  @TestMetadata("toDataFrameNoPublicPropertiesType.kt")
+  public void testToDataFrameNoPublicPropertiesType() {
+    runTest("testData/box/toDataFrameNoPublicPropertiesType.kt");
+  }
+
   @Test
   @TestMetadata("toDataFrameValueTypes.kt")
   public void testToDataFrameValueTypes() {