feat (core): Add finishReason field to NoObjectGeneratedError (#5541)

BramMeerten · bramm-4200 · web-flow · commit 772a2d719022 · 2025-04-04T16:15:00.000+02:00
Co-authored-by: Bram Meerten &lt;bram.meerten@acagroup.be&gt;
diff --git a/.changeset/flat-plums-bake.md b/.changeset/flat-plums-bake.md
@@ -0,0 +1,5 @@
+---
+'ai': minor
+---
+
+feat (core): Add finishReason field to NoObjectGeneratedError
diff --git a/content/docs/07-reference/05-ai-sdk-errors/ai-no-object-generated-error.mdx b/content/docs/07-reference/05-ai-sdk-errors/ai-no-object-generated-error.mdx
@@ -18,6 +18,7 @@ It can arise due to the following reasons:
 - `text`: The text that was generated by the model. This can be the raw text or the tool call text, depending on the object generation mode.
 - `response`: Metadata about the language model response, including response id, timestamp, and model.
 - `usage`: Request token usage.
+- `finishReason`: Request finish reason. For example 'length' if model generated maximum number of tokens, this could result in a JSON parsing error.
 - `cause`: The cause of the error (e.g. a JSON parsing error). You can use this for more detailed error handling.
 
 ## Checking for this Error
@@ -36,6 +37,7 @@ try {
     console.log('Text:', error.text);
     console.log('Response:', error.response);
     console.log('Usage:', error.usage);
+    console.log('Finish Reason:', error.finishReason);
   }
 }
 ```
diff --git a/packages/ai/core/generate-object/generate-object.test.ts b/packages/ai/core/generate-object/generate-object.test.ts
@@ -801,6 +801,7 @@ describe('output = "object"', () => {
           promptTokens: 10,
           totalTokens: 30,
         },
+        finishReason: 'stop',
       });
     }
 
diff --git a/packages/ai/core/generate-object/generate-object.ts b/packages/ai/core/generate-object/generate-object.ts
@@ -556,6 +556,7 @@ export async function generateObject<SCHEMA, RESULT>({
                       'No object generated: the model did not return a response.',
                     response: responseData,
                     usage: calculateLanguageModelUsage(result.usage),
+                    finishReason: result.finishReason,
                   });
                 }
 
@@ -681,6 +682,7 @@ export async function generateObject<SCHEMA, RESULT>({
                     message: 'No object generated: the tool was not called.',
                     response: responseData,
                     usage: calculateLanguageModelUsage(result.usage),
+                    finishReason: result.finishReason,
                   });
                 }
 
@@ -751,6 +753,7 @@ export async function generateObject<SCHEMA, RESULT>({
             text: result,
             response,
             usage: calculateLanguageModelUsage(usage),
+            finishReason: finishReason,
           });
         }
 
@@ -770,6 +773,7 @@ export async function generateObject<SCHEMA, RESULT>({
             text: result,
             response,
             usage: calculateLanguageModelUsage(usage),
+            finishReason: finishReason,
           });
         }
 
diff --git a/packages/ai/core/generate-object/output-strategy.ts b/packages/ai/core/generate-object/output-strategy.ts
@@ -16,7 +16,11 @@ import {
   createAsyncIterableStream,
 } from '../util/async-iterable-stream';
 import { ObjectStreamPart } from './stream-object-result';
-import { LanguageModelResponseMetadata, LanguageModelUsage } from '../types';
+import {
+  FinishReason,
+  LanguageModelResponseMetadata,
+  LanguageModelUsage,
+} from '../types';
 
 export interface OutputStrategy<PARTIAL, RESULT, ELEMENT_STREAM> {
   readonly type: 'object' | 'array' | 'enum' | 'no-schema';
@@ -64,6 +68,7 @@ const noSchemaOutputStrategy: OutputStrategy<JSONValue, JSONValue, never> = {
       text: string;
       response: LanguageModelResponseMetadata;
       usage: LanguageModelUsage;
+      finishReason: FinishReason;
     },
   ): ValidationResult<JSONValue> {
     return value === undefined
@@ -74,6 +79,7 @@ const noSchemaOutputStrategy: OutputStrategy<JSONValue, JSONValue, never> = {
             text: context.text,
             response: context.response,
             usage: context.usage,
+            finishReason: context.finishReason,
           }),
         }
       : { success: true, value };
diff --git a/packages/ai/core/generate-object/stream-object.test.ts b/packages/ai/core/generate-object/stream-object.test.ts
@@ -1311,6 +1311,7 @@ describe('streamObject', () => {
               modelId: 'model-1',
             },
             usage: { completionTokens: 10, promptTokens: 3, totalTokens: 13 },
+            finishReason: 'stop',
           });
         }
       });
@@ -1354,6 +1355,7 @@ describe('streamObject', () => {
               modelId: 'model-1',
             },
             usage: { completionTokens: 10, promptTokens: 3, totalTokens: 13 },
+            finishReason: 'stop',
           });
         }
       });
@@ -1403,6 +1405,7 @@ describe('streamObject', () => {
               modelId: 'model-1',
             },
             usage: { completionTokens: 10, promptTokens: 3, totalTokens: 13 },
+            finishReason: 'stop',
           });
         }
       });
@@ -1446,6 +1449,7 @@ describe('streamObject', () => {
               modelId: 'model-1',
             },
             usage: { completionTokens: 10, promptTokens: 3, totalTokens: 13 },
+            finishReason: 'stop',
           });
         }
       });
@@ -1488,6 +1492,7 @@ describe('streamObject', () => {
               modelId: 'model-1',
             },
             usage: { completionTokens: 10, promptTokens: 3, totalTokens: 13 },
+            finishReason: 'stop',
           });
         }
       });
@@ -1530,6 +1535,7 @@ describe('streamObject', () => {
               modelId: 'model-1',
             },
             usage: { completionTokens: 10, promptTokens: 3, totalTokens: 13 },
+            finishReason: 'stop',
           });
         }
       });
diff --git a/packages/ai/core/generate-object/stream-object.ts b/packages/ai/core/generate-object/stream-object.ts
@@ -898,6 +898,7 @@ class DefaultStreamObjectResult<PARTIAL, RESULT, ELEMENT_STREAM>
                         text: accumulatedText,
                         response,
                         usage,
+                        finishReason: finishReason,
                       });
                       self.objectPromise.reject(error);
                     }
diff --git a/packages/ai/core/generate-text/generate-text.ts b/packages/ai/core/generate-text/generate-text.ts
@@ -576,7 +576,11 @@ A function that attempts to repair a tool call that failed to parse.
 
           return output.parseOutput(
             { text },
-            { response: currentModelResponse.response, usage },
+            {
+              response: currentModelResponse.response,
+              usage,
+              finishReason: currentModelResponse.finishReason,
+            },
           );
         },
         toolCalls: currentToolCalls,
diff --git a/packages/ai/core/generate-text/output.test.ts b/packages/ai/core/generate-text/output.test.ts
@@ -2,6 +2,7 @@ import { fail } from 'assert';
 import { z } from 'zod';
 import { verifyNoObjectGeneratedError } from '../../errors/no-object-generated-error';
 import { object } from './output';
+import { FinishReason } from '../types';
 
 const context = {
   response: {
@@ -14,6 +15,7 @@ const context = {
     completionTokens: 2,
     totalTokens: 3,
   },
+  finishReason: 'length' as FinishReason,
 };
 
 describe('Output.object', () => {
@@ -37,6 +39,7 @@ describe('Output.object', () => {
         message: 'No object generated: could not parse the response.',
         response: context.response,
         usage: context.usage,
+        finishReason: context.finishReason,
       });
     }
   });
@@ -50,6 +53,7 @@ describe('Output.object', () => {
         message: 'No object generated: response did not match schema.',
         response: context.response,
         usage: context.usage,
+        finishReason: context.finishReason,
       });
     }
   });
diff --git a/packages/ai/core/generate-text/output.ts b/packages/ai/core/generate-text/output.ts
@@ -9,6 +9,7 @@ import { z } from 'zod';
 import { NoObjectGeneratedError } from '../../errors';
 import { injectJsonInstruction } from '../generate-object/inject-json-instruction';
 import {
+  FinishReason,
   LanguageModel,
   LanguageModelV1CallOptions,
 } from '../types/language-model';
@@ -33,6 +34,7 @@ export interface Output<OUTPUT, PARTIAL> {
     context: {
       response: LanguageModelResponseMetadata;
       usage: LanguageModelUsage;
+      finishReason: FinishReason;
     },
   ): OUTPUT;
 }
@@ -108,6 +110,7 @@ export const object = <OUTPUT>({
       context: {
         response: LanguageModelResponseMetadata;
         usage: LanguageModelUsage;
+        finishReason: FinishReason;
       },
     ) {
       const parseResult = safeParseJSON({ text });
@@ -119,6 +122,7 @@ export const object = <OUTPUT>({
           text,
           response: context.response,
           usage: context.usage,
+          finishReason: context.finishReason,
         });
       }
 
@@ -134,6 +138,7 @@ export const object = <OUTPUT>({
           text,
           response: context.response,
           usage: context.usage,
+          finishReason: context.finishReason,
         });
       }
 
diff --git a/packages/ai/errors/no-object-generated-error.ts b/packages/ai/errors/no-object-generated-error.ts
@@ -1,6 +1,7 @@
 import { AISDKError } from '@ai-sdk/provider';
 import { LanguageModelResponseMetadata } from '../core/types/language-model-response-metadata';
 import { LanguageModelUsage } from '../core/types/usage';
+import { FinishReason } from '../core';
 
 const name = 'AI_NoObjectGeneratedError';
 const marker = `vercel.ai.error.${name}`;
@@ -35,24 +36,32 @@ export class NoObjectGeneratedError extends AISDKError {
    */
   readonly usage: LanguageModelUsage | undefined;
 
+  /**
+  Reason why the model finished generating a response.
+   */
+  readonly finishReason: FinishReason | undefined;
+
   constructor({
     message = 'No object generated.',
     cause,
     text,
     response,
     usage,
+    finishReason,
   }: {
     message?: string;
     cause?: Error;
     text?: string;
     response: LanguageModelResponseMetadata;
     usage: LanguageModelUsage;
+    finishReason: FinishReason;
   }) {
     super({ name, message, cause });
 
     this.text = text;
     this.response = response;
     this.usage = usage;
+    this.finishReason = finishReason;
   }
 
   static isInstance(error: unknown): error is NoObjectGeneratedError {
@@ -66,11 +75,15 @@ export function verifyNoObjectGeneratedError(
     message: string;
     response: LanguageModelResponseMetadata;
     usage: LanguageModelUsage;
+    finishReason: FinishReason;
   },
 ) {
   expect(NoObjectGeneratedError.isInstance(error)).toBeTruthy();
   const noObjectGeneratedError = error as NoObjectGeneratedError;
   expect(noObjectGeneratedError.message).toStrictEqual(expected.message);
   expect(noObjectGeneratedError.response).toStrictEqual(expected.response);
   expect(noObjectGeneratedError.usage).toStrictEqual(expected.usage);
+  expect(noObjectGeneratedError.finishReason).toStrictEqual(
+    expected.finishReason,
+  );
 }

-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +---
 +'ai': minor
 +---
++
 +feat (core): Add finishReason field to NoObjectGeneratedError
Original file line number	Diff line number	Diff line change
`@@ -18,6 +18,7 @@ It can arise due to the following reasons:`
`18`	`18`	- `text`: The text that was generated by the model. This can be the raw text or the tool call text, depending on the object generation mode.
`19`	`19`	- `response`: Metadata about the language model response, including response id, timestamp, and model.
`20`	`20`	- `usage`: Request token usage.
	`21`	+- `finishReason`: Request finish reason. For example 'length' if model generated maximum number of tokens, this could result in a JSON parsing error.
`21`	`22`	- `cause`: The cause of the error (e.g. a JSON parsing error). You can use this for more detailed error handling.
`22`	`23`
`23`	`24`	`## Checking for this Error`
`@@ -36,6 +37,7 @@ try {`
`36`	`37`	`console.log('Text:', error.text);`
`37`	`38`	`console.log('Response:', error.response);`
`38`	`39`	`console.log('Usage:', error.usage);`
	`40`	`+ console.log('Finish Reason:', error.finishReason);`
`39`	`41`	`}`
`40`	`42`	`}`
`41`	`43`	```
Original file line number	Diff line number	Diff line change
`@@ -801,6 +801,7 @@ describe('output = "object"', () => {`
`801`	`801`	`promptTokens: 10,`
`802`	`802`	`totalTokens: 30,`
`803`	`803`	`},`
	`804`	`+ finishReason: 'stop',`
`804`	`805`	`});`
`805`	`806`	`}`
`806`	`807`
Original file line number	Diff line number	Diff line change
`@@ -898,6 +898,7 @@ class DefaultStreamObjectResult<PARTIAL, RESULT, ELEMENT_STREAM>`
`898`	`898`	`text: accumulatedText,`
`899`	`899`	`response,`
`900`	`900`	`usage,`
	`901`	`+ finishReason: finishReason,`
`901`	`902`	`});`
`902`	`903`	`self.objectPromise.reject(error);`
`903`	`904`	`}`