feat: omit some properties from error message, close #34

README.md

@@ -98,7 +98,7 @@ Now every time you use your schemas, pass the formats too so that the validator
 
 ```typescript
 // example JSON schema using uuid custom format
-const person100: ObjectSchema = {
+const employee100: ObjectSchema = {
   // has semantic version numbers
   version: {
     major: 1,
@@ -108,7 +108,7 @@ const person100: ObjectSchema = {
   // JSON schema
   schema: {
     type: 'object',
-    title: 'Person',
+    title: 'Employee',
     properties: {
       id: {
         type: 'string',
@@ -120,8 +120,8 @@ const person100: ObjectSchema = {
     id: 'a368dbfd-08e4-4698-b9a3-b2b660a11835',
   },
 }
-// person100 goes into "schemas", then
-assertSchema(schemas, formats)('person', '1.0.0')(someObject)
+// employee100 goes into "schemas", then
+assertSchema(schemas, formats)('Employee', '1.0.0')(someObject)
 ```
 
 ## API
@@ -207,6 +207,36 @@ try {
 }
 ```
 
+You can substitute some fields from example object to help with dynamic data. For example, to avoid breaking on invalid `id` value, we can tell `assertSchema` to use `id` value from the example object.
+
+```js
+const o = {
+  name: 'Mary',
+  age: -1,
+}
+assertSchema(schemas, formats)('Person', '1.0.0', {
+  substitutions: ['age'],
+})(o)
+// everything is good, because the actual object asserted was
+// {name: 'Mary', age: 10}
+```
+
+You can also limit the error message and omit some properties. Typically the error message with include list of errors, current and example objects, which might create a wall of text. To omit `object` and `example` but leave other fields when forming error message use
+
+```js
+const o = {
+  name: 'Mary',
+  age: -1,
+}
+assertSchema(schemas, formats)('Person', '1.0.0', {
+  omit: {
+    object: true,
+    example: true,
+  },
+})(o)
+// Error message is much much shorter, only "errors" and label will be there
+```
+
 ### bind
 
 There are multiple methods to validate, assert or sanitize an object against a schema. All take schemas and (optional) formats. But a project using schema tools probably has a single collection of schemas that it wants to use again and again. The `bind` method makes it easy to bind the first argument in each function to a schema collection and just call methods with an object later.

src/api.ts

@@ -31,6 +31,7 @@ import {
   prop,
   map,
   filter,
+  mergeDeepLeft,
 } from 'ramda'
 import stringify from 'json-stable-stringify'
 
@@ -270,43 +271,77 @@ export class SchemaError extends Error {
   }
 }
 
+type ErrorMessageWhiteList = {
+  errors: boolean
+  object: boolean
+  example: boolean
+}
+
+type AssertBySchemaOptions = {
+  substitutions: string[]
+  omit: Partial<ErrorMessageWhiteList>
+}
+
+const AssertBySchemaDefaults: AssertBySchemaOptions = {
+  substitutions: [],
+  omit: {
+    errors: false,
+    object: false,
+    example: false,
+  },
+}
+
 export const assertBySchema = (
   schema: JsonSchema,
   example: PlainObject = {},
-  substitutions: string[] = [],
+  options?: Partial<AssertBySchemaOptions>,
   label?: string,
   formats?: JsonSchemaFormats,
   schemaVersion?: SchemaVersion,
 ) => (object: PlainObject) => {
+  const allOptions = mergeDeepLeft(
+    options || AssertBySchemaDefaults,
+    AssertBySchemaDefaults,
+  )
+
   const replace = () => {
     const cloned = cloneDeep(object)
-    substitutions.forEach(property => {
+    allOptions.substitutions.forEach(property => {
       const value = get(example, property)
       set(cloned, property, value)
     })
     return cloned
   }
 
-  const replaced = substitutions.length ? replace() : object
+  const replaced = allOptions.substitutions.length ? replace() : object
   const result = validateBySchema(schema, formats)(replaced)
   if (result === true) {
     return object
   }
 
   const title = label ? `Schema ${label} violated` : 'Schema violated'
-  const start = [title, '', 'Errors:']
-    .concat(result)
-    .concat(['', 'Current object:'])
-  const objectString = stringify(replaced, { space: '  ' })
-  const exampleString = stringify(example, { space: '  ' })
-
-  const message =
-    start.join('\n') +
-    '\n' +
-    objectString +
-    '\n\n' +
-    'Expected object like this:\n' +
-    exampleString
+  const emptyLine = ''
+  let parts = [title]
+
+  if (!allOptions.omit.errors) {
+    parts = parts.concat([emptyLine, 'Errors:']).concat(result)
+  }
+
+  if (!allOptions.omit.object) {
+    const objectString = stringify(replaced, { space: '  ' })
+    parts = parts.concat([emptyLine, 'Current object:', objectString])
+  }
+
+  if (!allOptions.omit.example) {
+    const exampleString = stringify(example, { space: '  ' })
+    parts = parts.concat([
+      emptyLine,
+      'Expected object like this:',
+      exampleString,
+    ])
+  }
+
+  const message = parts.join('\n')
 
   throw new SchemaError(
     message,
@@ -338,9 +373,11 @@ export const assertBySchema = (
 export const assertSchema = (
   schemas: SchemaCollection,
   formats?: JsonSchemaFormats,
-) => (name: string, version: string, substitutions: string[] = []) => (
-  object: PlainObject,
-) => {
+) => (
+  name: string,
+  version: string,
+  options?: Partial<AssertBySchemaOptions>,
+) => (object: PlainObject) => {
   const example = getExample(schemas)(name)(version)
   const schema = getObjectSchema(schemas)(name)(version)
   if (!schema) {
@@ -352,7 +389,7 @@ export const assertSchema = (
   return assertBySchema(
     schema.schema,
     example,
-    substitutions,
+    options,
     label,
     formats,
     utils.semverToString(schema.version),

test/assert-schema-test.ts

@@ -83,7 +83,9 @@ test('passing membership invitation 1.0.0 with field substitution', t => {
     age: -1,
   }
   // replace "age" value with value from the example
-  const assert = assertSchema(schemas)('Person', '1.0.0', ['age'])
+  const assert = assertSchema(schemas)('Person', '1.0.0', {
+    substitutions: ['age'],
+  })
   const fn = () => assert(o)
   t.notThrows(fn)
 })
@@ -98,7 +100,10 @@ test('error message has object with substitutions', t => {
   }
   // replace "age" value with value from the example
   // but the "name" does not match schema format
-  const assert = assertSchema(schemas, formats)('Person', '1.0.0', ['age'])
+  const assert = assertSchema(schemas, formats)('Person', '1.0.0', {
+    substitutions: ['age'],
+  })
+
   try {
     assert(o)
   } catch (e) {
@@ -130,3 +135,23 @@ test('lists additional properties', t => {
     t.deepEqual(e.errors, ['data has additional properties: foo'])
   }
 })
+
+test('whitelist errors only', t => {
+  t.plan(1)
+
+  const o = {
+    name: 'test',
+    age: -2,
+  }
+  const assert = assertSchema(schemas)('Person', '1.0.0', {
+    omit: {
+      object: true,
+      example: true,
+    },
+  })
+  try {
+    assert(o)
+  } catch (e) {
+    t.snapshot(e.message)
+  }
+})

test/snapshots/assert-schema-test.ts.md

@@ -4,39 +4,45 @@ The actual snapshot is saved in `assert-schema-test.ts.snap`.
 
 Generated by [AVA](https://ava.li).
 
-## missing name membership invitation 1.0.0
+## error message has object with substitutions
 
-> Snapshot 1
+> error message
 
     `Schema Person@1.0.0 violated␊
     ␊
     Errors:␊
-    data.name is required␊
+    data.name must be name format␊
     ␊
     Current object:␊
     {␊
-      "age": 10␊
+      "age": 10,␊
+      "name": "lowercase"␊
     }␊
     ␊
     Expected object like this:␊
     {␊
       "age": 10,␊
       "name": "Joe"␊
-    }
+    }`
 
-## error message has object with substitutions
+> list of errors
 
-> error message
+    [
+      'data.name must be name format',
+    ]
+
+## missing name membership invitation 1.0.0
+
+> Snapshot 1
 
     `Schema Person@1.0.0 violated␊
     ␊
     Errors:␊
-    data.name must be name format␊
+    data.name is required␊
     ␊
     Current object:␊
     {␊
-      "age": 10,␊
-      "name": "lowercase"␊
+      "age": 10␊
     }␊
     ␊
     Expected object like this:␊
@@ -45,8 +51,11 @@ Generated by [AVA](https://ava.li).
       "name": "Joe"␊
     }`
 
-> list of errors
+## whitelist errors only
 
-    [
-      'data.name must be name format',
-    ]
+> Snapshot 1
+
+    `Schema Person@1.0.0 violated␊
+    ␊
+    Errors:␊
+    data.age is less than minimum`