Solvedtype graphql Getting "Schema must contain uniquely named types but contains multiple types named" for a single type

Hello, I have the following schema:

class Action {
  @Field(type => Skill, { nullable: true })
  skill?: Skill;

export class ActionResult {
  @Field(type => [Action])
  actions!: Action[];
  @Field({ nullable: true })
  count?: number

export class Skill {}

export class ActionResolver  extends BaseResolver {
  @Query(returns => ActionResult)
  async actions (@Args() args: ActionArgs, @Info() info){


  async skill(@Root() action: Action) {

export class SkillResolver extends BaseResolver {
  @Query(returns => [Skill])
  async allSkills (){


From this I generate a schema like this:

  return buildSchema({
    resolvers: [ActionResolver, SkillResolver],
    emitSchemaFile: { path: 'schema.graphql' },

And I get the error:

UnhandledPromiseRejectionWarning: Error: Schema must contain uniquely named types but contains multiple types named "Skill".
42 Answers

βœ”οΈAccepted Answer

This was a hard one to track down, with an annoying fix (Nest specific, not the fault of type-graphql). For anyone experiencing the same issue make sure to delete dist/ directory and run the app again.

Other Answers:

I found one way to produce this bug. Took me a long time to figure out! If you import a file from 2 other files but you type its path with 2 different casings, the TypeScript compiler will include 2 copies of the module in the transpiled JS. This causes any types to be registered multiple times. For example:

// recipe.ts
export class Recipe {
// ...
// file1.ts
import { Recipe } from './recipe';
console.log(Recipe); // Use it so the import doesn't get optimized away.
// file2.ts
import { Recipe } from './Recipe'; // Notice the capital R
console.log(Recipe); // Use it again.

Error: Schema must contain uniquely named types but contains multiple types named "Recipe".

Of course, the import statements should match the casing of the actual file. But the macOS filesystem is not case sensitive so it recognizes the file even when the import statement has the wrong casing. There is the compiler option forceConsistentCasingInFileNames that detects bugs like this. Strangely it's turned off by default.

@gotenxds Was this also the cause in your case?

For anyone who is struggling with this issue and tried above recipes with no luck: try to implicitly give a name to your types. My issue was solved with following

export class User {

Note an arg that was passed to ObjectType

Complete solution in case if class is used as input and output:

export class DataStruct { ... }

@christopher-avila Your ormconfig.js is referencing the TS file for your entity:

You should either configure typeorm from a TS file or use the "dist/" path to the JS files:

entities: ["dist/entities/*.js"]

This fixes the problem. πŸ™‚

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