🔀 Merge errors with path information

Errors with path
michaljanocko · Jun 1, 2022 · 84828e0 · 84828e0
2 parents 09a700b + 6e3f911
commit 84828e0
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Showing 2 changed files with 134 additions and 6 deletions.
diff --git a/src/index.ts b/src/index.ts
@@ -51,10 +51,30 @@ export const createDecoder = <D>(decoder: Decode<D>): Decoder<D> => ({
 })
 
 export class DecoderError extends SyntaxError {
-  constructor (message?: string) {
+  path: string[]
+  constructor (message?: string, path: string[] = []) {
     super(message)
     this.name = 'DecoderError'
+    this.path = path
     Object.setPrototypeOf(this, new.target.prototype)
+
+    if (this.path.length === 1) {
+      this.message = `${this.path[0]}: ${this.message}`
+    } else if (this.path.length > 1) {
+      this.message = `${this.path[0]}.${this.message}`
+    }
+  }
+}
+
+const forceDecodeWithPath = <T>(decoder: Decoder<T>, data: unknown, pathPart: string): T => {
+  try {
+    return decoder.forceDecode(data)
+  } catch (e) {
+    if (e instanceof DecoderError) {
+      throw new DecoderError(e.message, [pathPart, ...e.path])
+    } else {
+      throw e
+    }
   }
 }
 
@@ -161,7 +181,7 @@ export const array = <D>(decoder: Decoder<D>): Decoder<D[]> => createDecoder({
   forceDecode: (data) => {
     checkDefined(data)
     checkArrayType(data)
-    return data.map(decoder.forceDecode)
+    return data.map((x: unknown, i) => forceDecodeWithPath(decoder, x, i.toString()))
   }
 })
 
@@ -178,7 +198,7 @@ export const tuple = <D extends readonly unknown[]>(
       }
 
       return decoders.map((decoder, index) =>
-        decoder.forceDecode(data[index])
+        forceDecodeWithPath(decoder, data[index], index.toString())
       ) as any as D
     }
   })
@@ -200,7 +220,7 @@ export const record = <D>(decoder: Decoder<D>): Decoder<Record<string, D>> => cr
     checkDefined(data)
     checkDictType(data)
     return Object.fromEntries(
-      Object.entries(data).map(([key, value]) => [key, decoder.forceDecode(value)])
+      Object.entries(data).map(([key, value]) => [key, forceDecodeWithPath(decoder, value, key)])
     )
   }
 })
@@ -227,7 +247,7 @@ const required = <D extends DecoderRecord>(
 
       for (const key in struct) {
         if (data[key] === undefined) throw new DecoderError(`Object missing required property '${key}'`)
-        parsed[key] = struct[key].forceDecode(data[key])
+        parsed[key] = forceDecodeWithPath(struct[key], data[key], key)
       }
 
       return parsed as ObjectType<D>
@@ -244,7 +264,7 @@ const partial = <D extends DecoderRecord>(
 
       for (const key in struct) {
         if (data[key] !== undefined) {
-          parsed[key] = struct[key].forceDecode(data[key])
+          parsed[key] = forceDecodeWithPath(struct[key], data[key], key)
         }
       }
 

diff --git a/test/index.test.ts b/test/index.test.ts
@@ -329,3 +329,111 @@ test('Decoder.validate on invalid data returns error', () => {
 test('Decoder.validate on valid data returns ok', () => {
   expect(D.string.validate('hi')).toStrictEqual({ type: 'ok', data: 'hi' })
 })
+
+test('DecodeError path of tuple is correct', () => {
+  const result = D.tuple(D.string, D.string).validate(["h1", 2]);
+  if (result.type === "error") {
+    expect(result.error.message).toStrictEqual("1: This is not a string: 2")
+  } else {
+    fail("Expected error")
+  }
+})
+
+test('DecodeError path of an array is correct', () => {
+  const result = D.array(D.string).validate(["h1", "h2", 3.14]);
+  if (result.type === "error") {
+    expect(result.error.message).toStrictEqual("2: This is not a string: 3.14")
+  } else {
+    fail("Expected error")
+  }
+})
+
+test('DecodeError path of an object required key is correct', () => {
+  const result = D.object({required: {name: D.string}}).validate({name: 1});
+  if (result.type === "error") {
+    expect(result.error.message).toStrictEqual("name: This is not a string: 1")
+  } else {
+    fail("Expected error")
+  }
+})
+
+test('DecodeError path of an object optional key is correct', () => {
+  const result = D.object({optional: {name: D.string}}).validate({name: 1});
+  if (result.type === "error") {
+    expect(result.error.message).toStrictEqual("name: This is not a string: 1")
+  } else {
+    fail("Expected error")
+  }
+})
+
+test('DecodeError path of a record is correct', () => {
+  const result = D.record(D.object({required: {name: D.string}})).validate({"charles": {name: 1}});
+  if (result.type === "error") {
+    expect(result.error.message).toStrictEqual("charles.name: This is not a string: 1")
+  } else {
+    fail("Expected error")
+  }
+})
+
+test('DecodeError path of a key value pair is correct', () => {
+  const result = D.keyValuePairs(D.object({required: {name: D.string}})).validate({"charles": {name: 1}});
+  if (result.type === "error") {
+    expect(result.error.message).toStrictEqual("charles.name: This is not a string: 1")
+  } else {
+    fail("Expected error")
+  }
+})
+
+test('DecodeError path of a nested object is correct', () => {
+  const result = D.object({optional: {sub: D.object({required: {name: D.string}})}}).validate({sub:{name: 1}});
+  if (result.type === "error") {
+    expect(result.error.message).toStrictEqual("sub.name: This is not a string: 1")
+  } else {
+    fail("Expected error")
+  }
+})
+
+test('DecodeError path of a recursive type is correct', () => {
+
+  const categories: any = {
+    name: 'Electronics',
+    subcategories: [
+      {
+        name: 'Computers',
+        subcategories: [
+          { name: 'Desktops', subcategories: [] },
+          { name: 1, subcategories: [] }
+        ]
+      },
+      { name: 'Fridges', subcategories: [] }
+    ]
+  }
+
+  interface Category {
+    name: string,
+    subcategories: Category[]
+  }
+
+  const categoryDecoder: D.Decoder<Category> = D.object({
+    required: {
+      name: D.string,
+      subcategories: D.array(D.recursive(() => categoryDecoder))
+    }
+  })
+
+  const categoryDecoder_: D.Decoder<Category> = D.recursive(() =>
+    D.object({
+      required: {
+        name: D.string,
+        subcategories: D.array(categoryDecoder_)
+      }
+    })
+  )
+
+  const result = categoryDecoder_.validate(categories);
+  if (result.type === "error") {
+    expect(result.error.message).toStrictEqual("subcategories.0.subcategories.1.name: This is not a string: 1")
+  } else {
+    fail("Expected error")
+  }
+})