Fix type name conflicts when using generic interfaces (#4)

Author: daniel-chambers

CHANGELOG.md

@@ -5,6 +5,7 @@ This changelog documents the changes between release versions.
 Changes to be included in the next upcoming release
 
 - Add support for JSDoc descriptions from object types ([#3](https://github.com/hasura/ndc-nodejs-lambda/pull/3))
+- Fix type name conflicts when using generic interfaces ([#4](https://github.com/hasura/ndc-nodejs-lambda/pull/4))
 
 ## v0.11.0
 - Add support for parallel execution of readonly functions ([#2](https://github.com/hasura/ndc-nodejs-lambda/pull/2))

ndc-lambda-sdk/src/inference.ts

@@ -518,18 +518,21 @@ function getObjectTypeInfo(tsType: ts.Type, typePath: TypePathSegment[], typeChe
   }
   // Interface type - this covers:
   // interface IThing { test: string }
+  // type AliasedIThing = IThing (the alias is erased by the compiler)
   else if (tsutils.isObjectType(tsType) && tsutils.isObjectFlagSet(tsType, ts.ObjectFlags.Interface)) {
     return {
-      generatedTypeName: tsType.getSymbol()?.name ?? generateTypeNameFromTypePath(typePath),
+      generatedTypeName: typeChecker.typeToString(tsType),
       properties: getMembers(tsType.getProperties(), typeChecker),
       description,
     }
   }
   // Generic interface type - this covers:
   // interface IGenericThing<T> { data: T }
+  // type AliasedIGenericThing<T> = IGenericThing<T>
+  // type AliasedClosedIGenericThing = IGenericThing<string>
   else if (tsutils.isTypeReference(tsType) && tsutils.isObjectFlagSet(tsType.target, ts.ObjectFlags.Interface) && typeChecker.isArrayType(tsType) === false && tsType.getSymbol()?.getName() !== "Promise") {
     return {
-      generatedTypeName: tsType.getSymbol()?.name ?? generateTypeNameFromTypePath(typePath),
+      generatedTypeName: typeChecker.typeToString(tsType),
       properties: getMembers(tsType.getProperties(), typeChecker),
       description,
     }

ndc-lambda-sdk/test/inference/basic-inference/basic-inference.test.ts

@@ -311,13 +311,40 @@ describe("basic inference", function() {
                   name: "IThing"
                 }
               },
+              {
+                argumentName: "aliasedInterface",
+                description: null,
+                type: {
+                  type: "named",
+                  kind: "object",
+                  name: "IThing"
+                }
+              },
               {
                 argumentName: "genericInterface",
                 description: null,
                 type: {
                   type: "named",
                   kind: "object",
-                  name: "IGenericThing"
+                  name: "IGenericThing<string>"
+                }
+              },
+              {
+                argumentName: "aliasedGenericInterface",
+                description: null,
+                type: {
+                  type: "named",
+                  kind: "object",
+                  name: "AliasedIGenericThing<number>"
+                }
+              },
+              {
+                argumentName: "aliasedClosedInterface",
+                description: null,
+                type: {
+                  type: "named",
+                  kind: "object",
+                  name: "AliasedClosedIGenericThing"
                 }
               },
               {
@@ -421,7 +448,7 @@ describe("basic inference", function() {
               },
             ],
           },
-          "IGenericThing": {
+          "IGenericThing<string>": {
             description: null,
             properties: [
               {
@@ -435,6 +462,34 @@ describe("basic inference", function() {
               },
             ],
           },
+          "AliasedIGenericThing<number>": {
+            description: null,
+            properties: [
+              {
+                propertyName: "data",
+                description: null,
+                type: {
+                  name: "Float",
+                  kind: "scalar",
+                  type: "named",
+                },
+              },
+            ],
+          },
+          "AliasedClosedIGenericThing": {
+            description: null,
+            properties: [
+              {
+                propertyName: "data",
+                description: null,
+                type: {
+                  name: "Float",
+                  kind: "scalar",
+                  type: "named",
+                },
+              },
+            ],
+          },
           "IThing": {
             description: null,
             properties: [

ndc-lambda-sdk/test/inference/basic-inference/complex-types.ts

@@ -10,16 +10,25 @@ interface IThing {
   prop: string
 }
 
+// This alias just gets erased by the TS compiler
+type AliasedIThing = IThing;
+
 interface IGenericThing<T> {
   data: T
 }
 
+type AliasedIGenericThing<T> = IGenericThing<T>
+
+type AliasedClosedIGenericThing = IGenericThing<number>
+
 type IntersectionObject = { wow: string } & Bar
 
 type GenericIntersectionObject<T> = { data: T } & Bar
 
+// This alias just gets erased by the TS compiler
 type AliasedString = string;
 
+// These aliases just get erased by the TS compiler
 type GenericScalar<T> = GenericScalar2<T>
 type GenericScalar2<T> = T
 
@@ -33,7 +42,10 @@ export function bar(
   genericAliasedObj: GenericBar<string>,
   genericAliasedObjWithComplexTypeParam: GenericBar<Bar>,
   interfce: IThing,
+  aliasedInterface: AliasedIThing,
   genericInterface: IGenericThing<string>,
+  aliasedGenericInterface: AliasedIGenericThing<number>,
+  aliasedClosedInterface: AliasedClosedIGenericThing,
   aliasedIntersectionObj: IntersectionObject,
   anonIntersectionObj: {num:number} & Bar,
   genericIntersectionObj: GenericIntersectionObject<string>,

ndc-lambda-sdk/test/inference/type-descriptions/type-descriptions.test.ts

@@ -77,7 +77,7 @@ describe("type descriptions", function() {
                 argumentName: "genericInterface",
                 description: null,
                 type: {
-                  name: "IGenericInterface",
+                  name: "IGenericInterface<string>",
                   kind: "object",
                   type: "named",
                 }
@@ -131,7 +131,7 @@ describe("type descriptions", function() {
               }
             ]
           },
-          "IGenericInterface": {
+          "IGenericInterface<string>": {
             description: "The most generic of interfaces",
             properties: [
               {