refactor: Reduce coupling with Type (#119)

The current implementation is heavily coupled to `Type` which itself is
heavily coupled to actual Kotlin classes. This tries to move away from
`Type` when it is not needed to simplify working with non-Kotlin schemas
(like schemas created from SDL or introspection queries).

kgraphql/src/main/kotlin/com/apurebase/kgraphql/schema/DefaultSchema.kt

@@ -71,4 +71,6 @@ class DefaultSchema(
     override fun typeByKClass(kClass: KClass<*>): Type? = model.queryTypes[kClass]
 
     override fun inputTypeByKClass(kClass: KClass<*>): Type? = model.inputTypes[kClass]
+
+    override fun findTypeByName(name: String): Type? = model.allTypesByName[name]
 }

kgraphql/src/main/kotlin/com/apurebase/kgraphql/schema/SchemaPrinter.kt

@@ -9,7 +9,6 @@ import com.apurebase.kgraphql.schema.introspection.__Directive
 import com.apurebase.kgraphql.schema.introspection.__InputValue
 import com.apurebase.kgraphql.schema.introspection.__Schema
 import com.apurebase.kgraphql.schema.introspection.__Type
-import com.apurebase.kgraphql.schema.introspection.typeReference
 import com.apurebase.kgraphql.schema.model.Depreciable
 
 data class SchemaPrinterConfig(

kgraphql/src/main/kotlin/com/apurebase/kgraphql/schema/execution/ArgumentTransformer.kt

@@ -5,7 +5,6 @@ import com.apurebase.kgraphql.InvalidInputValueException
 import com.apurebase.kgraphql.request.Variables
 import com.apurebase.kgraphql.schema.introspection.TypeKind
 import com.apurebase.kgraphql.schema.introspection.__Schema
-import com.apurebase.kgraphql.schema.introspection.typeReference
 import com.apurebase.kgraphql.schema.model.ast.ArgumentNodes
 import com.apurebase.kgraphql.schema.model.ast.ValueNode
 import com.apurebase.kgraphql.schema.model.ast.ValueNode.ObjectValueNode

kgraphql/src/main/kotlin/com/apurebase/kgraphql/schema/execution/DataLoaderPreparedRequestExecutor.kt

@@ -9,6 +9,8 @@ import com.apurebase.kgraphql.request.Variables
 import com.apurebase.kgraphql.request.VariablesJson
 import com.apurebase.kgraphql.schema.DefaultSchema
 import com.apurebase.kgraphql.schema.introspection.TypeKind
+import com.apurebase.kgraphql.schema.introspection.__Field
+import com.apurebase.kgraphql.schema.introspection.__Type
 import com.apurebase.kgraphql.schema.model.FunctionWrapper
 import com.apurebase.kgraphql.schema.model.ast.ArgumentNodes
 import com.apurebase.kgraphql.schema.scalar.serializeScalar
@@ -76,7 +78,7 @@ class DataLoaderPreparedRequestExecutor(val schema: DefaultSchema) : RequestExec
         applyKeyToElement(ctx, result, node, node.field.returnType, 1)
     }
 
-    private fun Any?.toPrimitive(node: Execution.Node, returnType: Type): JsonElement = when {
+    private fun Any?.toPrimitive(node: Execution.Node, returnType: __Type): JsonElement = when {
         this == null -> createNullNode(node, returnType.unwrapList())
         this is Collection<*> || this is Array<*> -> when (this) {
             is Array<*> -> toList()
@@ -97,7 +99,7 @@ class DataLoaderPreparedRequestExecutor(val schema: DefaultSchema) : RequestExec
         ctx: ExecutionContext,
         value: T?,
         node: Execution.Node,
-        returnType: Type,
+        returnType: __Type,
         parentCount: Long
     ) {
         return when {
@@ -162,22 +164,22 @@ class DataLoaderPreparedRequestExecutor(val schema: DefaultSchema) : RequestExec
         }
     }
 
-    private fun <T> createSimpleValueNode(returnType: Type, value: T, node: Execution.Node): JsonElement {
+    private fun <T> createSimpleValueNode(returnType: __Type, value: T, node: Execution.Node): JsonElement {
         return when (val unwrapped = returnType.unwrapped()) {
             is Type.Scalar<*> -> {
                 serializeScalar(unwrapped, value, node)
             }
 
             is Type.Enum<*> -> JsonPrimitive(value.toString())
-            else -> throw ExecutionException("Invalid Type:  ${returnType.name}", node)
+            else -> throw ExecutionException("Invalid Type: ${unwrapped.name}", node)
         }
     }
 
     private suspend fun <T> DeferredJsonMap.applyObjectProperties(
         ctx: ExecutionContext,
         value: T,
         node: Execution.Node,
-        type: Type,
+        type: __Type,
         parentCount: Long
     ) {
         node.children.map { child ->
@@ -197,7 +199,9 @@ class DataLoaderPreparedRequestExecutor(val schema: DefaultSchema) : RequestExec
             return
         }
 
-        val expectedType = container.condition.type
+        val expectedType = checkNotNull(schema.findTypeByName(container.condition.onType)) {
+            "Unable to find type ${container.condition.onType}"
+        }
 
         if (expectedType.kind == TypeKind.OBJECT || expectedType.kind == TypeKind.INTERFACE) {
             if (expectedType.isInstance(value)) {
@@ -223,7 +227,8 @@ class DataLoaderPreparedRequestExecutor(val schema: DefaultSchema) : RequestExec
     private suspend fun <T> DeferredJsonMap.applyProperty(
         ctx: ExecutionContext,
         value: T,
-        child: Execution, type: Type,
+        child: Execution,
+        type: __Type,
         parentCount: Long
     ) {
         when (child) {
@@ -286,7 +291,7 @@ class DataLoaderPreparedRequestExecutor(val schema: DefaultSchema) : RequestExec
         ctx: ExecutionContext,
         parentValue: T,
         node: Execution.Node,
-        field: Field,
+        field: __Field,
         parentCount: Long
     ) {
         node.field.checkAccess(parentValue, ctx.requestContext)
@@ -296,11 +301,7 @@ class DataLoaderPreparedRequestExecutor(val schema: DefaultSchema) : RequestExec
 
         when (field) {
             is Field.Kotlin<*, *> -> {
-                val rawValue = try {
-                    (field.kProperty as KProperty1<T, *>).get(parentValue)
-                } catch (e: NullPointerException) {
-                    throw e
-                }
+                val rawValue = (field.kProperty as KProperty1<T, *>).get(parentValue)
                 val value: Any? = field.transformation?.invoke(
                     funName = field.name,
                     receiver = rawValue,
@@ -322,7 +323,7 @@ class DataLoaderPreparedRequestExecutor(val schema: DefaultSchema) : RequestExec
                 handleDataPropertyAsync(ctx, parentValue, node, field, parentCount)
             }
 
-            else -> error("Only Kotlin Fields are supported!")
+            else -> error("Unexpected field type: $field, should be Field.Kotlin, Field.Function or Field.DataLoader")
         }
     }
 
@@ -395,11 +396,12 @@ class DataLoaderPreparedRequestExecutor(val schema: DefaultSchema) : RequestExec
             result.await().toString()
         }
 
-    private fun createNullNode(node: Execution.Node, returnType: Type): JsonNull = if (returnType !is Type.NonNull) {
-        JsonNull
-    } else {
-        throw ExecutionException("null result for non-nullable operation ${node.field}", node)
-    }
+    private fun createNullNode(node: Execution.Node, returnType: __Type): JsonNull =
+        if (returnType.kind != TypeKind.NON_NULL) {
+            JsonNull
+        } else {
+            throw ExecutionException("null result for non-nullable operation ${node.field}", node)
+        }
 
     private suspend fun shouldInclude(ctx: ExecutionContext, executionNode: Execution): Boolean {
         if (executionNode.directives?.isEmpty() == true) {

kgraphql/src/main/kotlin/com/apurebase/kgraphql/schema/execution/Execution.kt

@@ -2,8 +2,8 @@ package com.apurebase.kgraphql.schema.execution
 
 import com.apurebase.kgraphql.schema.directive.Directive
 import com.apurebase.kgraphql.schema.introspection.NotIntrospected
+import com.apurebase.kgraphql.schema.introspection.__Type
 import com.apurebase.kgraphql.schema.structure.Field
-import com.apurebase.kgraphql.schema.structure.Type
 import com.apurebase.kgraphql.schema.model.ast.ArgumentNodes
 import com.apurebase.kgraphql.schema.model.ast.SelectionNode
 import com.apurebase.kgraphql.schema.model.ast.VariableDefinitionNode
@@ -37,7 +37,7 @@ sealed class Execution {
     class Union(
         node: SelectionNode,
         val unionField: Field.Union<*>,
-        val memberChildren: Map<Type, Collection<Execution>>,
+        val memberChildren: Map<__Type, Collection<Execution>>,
         key: String,
         alias: String? = null,
         condition: TypeCondition? = null,
@@ -51,7 +51,7 @@ sealed class Execution {
         typeCondition = condition,
         directives = directives
     ) {
-        fun memberExecution(type: Type): Node {
+        fun memberExecution(type: __Type): Node {
             return Node(
                 selectionNode = selectionNode,
                 field = field,

kgraphql/src/main/kotlin/com/apurebase/kgraphql/schema/execution/ParallelRequestExecutor.kt

@@ -7,6 +7,8 @@ import com.apurebase.kgraphql.request.Variables
 import com.apurebase.kgraphql.request.VariablesJson
 import com.apurebase.kgraphql.schema.DefaultSchema
 import com.apurebase.kgraphql.schema.introspection.TypeKind
+import com.apurebase.kgraphql.schema.introspection.__Field
+import com.apurebase.kgraphql.schema.introspection.__Type
 import com.apurebase.kgraphql.schema.model.FunctionWrapper
 import com.apurebase.kgraphql.schema.model.ast.ArgumentNodes
 import com.apurebase.kgraphql.schema.scalar.serializeScalar
@@ -129,7 +131,7 @@ class ParallelRequestExecutor(val schema: DefaultSchema) : RequestExecutor {
         ctx: ExecutionContext,
         value: T?,
         node: Execution.Node,
-        returnType: Type
+        returnType: __Type
     ): JsonNode {
         if (value == null) {
             return createNullNode(node, returnType)
@@ -140,7 +142,7 @@ class ParallelRequestExecutor(val schema: DefaultSchema) : RequestExecutor {
         }
 
         return when {
-            //check value, not returnType, because this method can be invoked with element value
+            // Check value, not returnType, because this method can be invoked with element value
             value is Collection<*> || value is Array<*> -> {
                 val values: Collection<*> = when (value) {
                     is Array<*> -> value.toList()
@@ -178,7 +180,7 @@ class ParallelRequestExecutor(val schema: DefaultSchema) : RequestExecutor {
         }
     }
 
-    private fun <T> createSimpleValueNode(returnType: Type, value: T, node: Execution.Node): JsonNode =
+    private fun <T> createSimpleValueNode(returnType: __Type, value: T, node: Execution.Node): JsonNode =
         when (val unwrapped = returnType.unwrapped()) {
             is Type.Scalar<*> -> {
                 serializeScalar(jsonNodeFactory, unwrapped, value, node)
@@ -188,11 +190,11 @@ class ParallelRequestExecutor(val schema: DefaultSchema) : RequestExecutor {
                 jsonNodeFactory.textNode(value.toString())
             }
 
-            else -> throw ExecutionException("Invalid Type:  ${returnType.name}", node)
+            else -> throw ExecutionException("Invalid Type: ${unwrapped.name}", node)
         }
 
-    private fun createNullNode(node: Execution.Node, returnType: Type): NullNode {
-        if (returnType !is Type.NonNull) {
+    private fun createNullNode(node: Execution.Node, returnType: __Type): NullNode {
+        if (returnType.kind != TypeKind.NON_NULL) {
             return jsonNodeFactory.nullNode()
         } else {
             throw ExecutionException("null result for non-nullable operation ${node.field}", node)
@@ -203,7 +205,7 @@ class ParallelRequestExecutor(val schema: DefaultSchema) : RequestExecutor {
         ctx: ExecutionContext,
         value: T,
         node: Execution.Node,
-        type: Type
+        type: __Type
     ): ObjectNode {
         val objectNode = jsonNodeFactory.objectNode()
         for (child in node.children) {
@@ -222,7 +224,7 @@ class ParallelRequestExecutor(val schema: DefaultSchema) : RequestExecutor {
         ctx: ExecutionContext,
         value: T,
         child: Execution,
-        type: Type
+        type: __Type
     ): Pair<String, JsonNode?>? {
         when (child) {
             // Union is subclass of Node so check it first
@@ -255,7 +257,9 @@ class ParallelRequestExecutor(val schema: DefaultSchema) : RequestExecutor {
         value: T,
         container: Execution.Fragment
     ): Map<String, JsonNode?> {
-        val expectedType = container.condition.type
+        val expectedType = checkNotNull(schema.findTypeByName(container.condition.onType)) {
+            "Unable to find type ${container.condition.onType}"
+        }
         val include = shouldInclude(ctx, container)
 
         if (include) {
@@ -286,7 +290,7 @@ class ParallelRequestExecutor(val schema: DefaultSchema) : RequestExecutor {
         ctx: ExecutionContext,
         parentValue: T,
         node: Execution.Node,
-        field: Field
+        field: __Field
     ): JsonNode? {
         val include = shouldInclude(ctx, node)
         node.field.checkAccess(parentValue, ctx.requestContext)
@@ -322,9 +326,7 @@ class ParallelRequestExecutor(val schema: DefaultSchema) : RequestExecutor {
                     return handleDataProperty(ctx, parentValue, node, field)
                 }
 
-                else -> {
-                    throw Exception("Unexpected field type: $field, should be Field.Kotlin or Field.Function")
-                }
+                else -> error("Unexpected field type: $field, should be Field.Kotlin, Field.Function or Field.DataLoader")
             }
         } else {
             return null
@@ -406,6 +408,7 @@ class ParallelRequestExecutor(val schema: DefaultSchema) : RequestExecutor {
             executionNode,
             ctx.requestContext
         )
+
         // exceptions are not caught on purpose to pass up business logic errors
         return try {
             when {

kgraphql/src/main/kotlin/com/apurebase/kgraphql/schema/execution/TypeCondition.kt

@@ -1,8 +1,6 @@
 package com.apurebase.kgraphql.schema.execution
 
-import com.apurebase.kgraphql.schema.structure.Type
-
 /**
  * type conditions can be declared on fragments
  */
-class TypeCondition(val type: Type)
+class TypeCondition(val onType: String)

kgraphql/src/main/kotlin/com/apurebase/kgraphql/schema/introspection/SchemaProxy.kt

@@ -26,6 +26,4 @@ class SchemaProxy(
 
     override val directives: List<__Directive>
         get() = getProxied().directives
-
-    override fun findTypeByName(name: String): __Type? = getProxied().findTypeByName(name)
 }

kgraphql/src/main/kotlin/com/apurebase/kgraphql/schema/introspection/__Schema.kt

@@ -1,7 +1,6 @@
 package com.apurebase.kgraphql.schema.introspection
 
 interface __Schema {
-
     val types: List<__Type>
 
     val queryType: __Type
@@ -11,6 +10,4 @@ interface __Schema {
     val subscriptionType: __Type?
 
     val directives: List<__Directive>
-
-    fun findTypeByName(name: String): __Type?
 }

kgraphql/src/main/kotlin/com/apurebase/kgraphql/schema/introspection/__Type.kt

@@ -26,10 +26,28 @@ interface __Type {
 
     // NON_NULL and LIST only
     val ofType: __Type?
-}
 
-fun __Type.typeReference(): String = when (kind) {
-    TypeKind.NON_NULL -> "${ofType?.typeReference()}!"
-    TypeKind.LIST -> "[${ofType?.typeReference()}]"
-    else -> name ?: ""
+    operator fun get(name: String): __Field? = null
+
+    fun isList(): Boolean = when {
+        kind == TypeKind.LIST -> true
+        ofType == null -> false
+        else -> (ofType as __Type).isList()
+    }
+
+    fun typeReference(): String = when (kind) {
+        TypeKind.NON_NULL -> "${ofType?.typeReference()}!"
+        TypeKind.LIST -> "[${ofType?.typeReference()}]"
+        else -> name ?: ""
+    }
+
+    fun unwrapped(): __Type = when (kind) {
+        TypeKind.NON_NULL, TypeKind.LIST -> ofType!!.unwrapped()
+        else -> this
+    }
+
+    fun unwrapList(): __Type = when (kind) {
+        TypeKind.LIST -> ofType as __Type
+        else -> ofType?.unwrapList() ?: throw NoSuchElementException("this type does not wrap list element")
+    }
 }

kgraphql/src/main/kotlin/com/apurebase/kgraphql/schema/model/TypeDef.kt

@@ -47,7 +47,7 @@ interface TypeDef {
         fun toScalarType(): Type.Scalar<T> = Type.Scalar(this)
     }
 
-    //To avoid circular dependencies etc. union type members are resolved in runtime
+    // To avoid circular dependencies etc. union type members are resolved in runtime
     class Union(
         name: String,
         val members: Set<KClass<*>>,