kbn-config-schema: allow parsing of array and object types from string (#57189) (#57298)

* allow parsing from string for object-ish and array types

* update snapshots

* fix FTR assertion

* add documentation note about using a json string as input

packages/kbn-config-schema/README.md

@@ -227,6 +227,9 @@ __Usage:__
 const valueSchema = schema.arrayOf(schema.number());
 ```
 
+__Notes:__
+* The `schema.arrayOf()` also supports a json string as input if it can be safely parsed using `JSON.parse` and if the resulting value is an array.
+
 #### `schema.object()`
 
 Validates input data as an object with a predefined set of properties.
@@ -249,6 +252,7 @@ const valueSchema = schema.object({
 __Notes:__
 * Using `allowUnknowns` is discouraged and should only be used in exceptional circumstances. Consider using `schema.recordOf()` instead.
 * Currently `schema.object()` always has a default value of `{}`, but this may change in the near future. Try to not rely on this behaviour and specify default value explicitly or use `schema.maybe()` if the value is optional.
+* `schema.object()` also supports a json string as input if it can be safely parsed using `JSON.parse` and if the resulting value is a plain object.
 
 #### `schema.recordOf()`
 
@@ -267,6 +271,7 @@ const valueSchema = schema.recordOf(schema.string(), schema.number());
 
 __Notes:__
 * You can use a union of literal types as a record's key schema to restrict record to a specific set of keys, e.g. `schema.oneOf([schema.literal('isEnabled'), schema.literal('name')])`.
+* `schema.recordOf()` also supports a json string as input if it can be safely parsed using `JSON.parse` and if the resulting value is a plain object.
 
 #### `schema.mapOf()`
 
@@ -283,6 +288,10 @@ __Usage:__
 const valueSchema = schema.mapOf(schema.string(), schema.number());
 ```
 
+__Notes:__
+* You can use a union of literal types as a record's key schema to restrict record to a specific set of keys, e.g. `schema.oneOf([schema.literal('isEnabled'), schema.literal('name')])`.
+* `schema.mapOf()` also supports a json string as input if it can be safely parsed using `JSON.parse` and if the resulting value is a plain object.
+
 ### Advanced types
 
 #### `schema.oneOf()`

packages/kbn-config-schema/src/internals/index.ts

@@ -250,12 +250,23 @@ export const internals = Joi.extend([
 
     base: Joi.object(),
     coerce(value: any, state: State, options: ValidationOptions) {
-      // If value isn't defined, let Joi handle default value if it's defined.
-      if (value !== undefined && !isPlainObject(value)) {
-        return this.createError('object.base', { value }, state, options);
+      if (value === undefined || isPlainObject(value)) {
+        return value;
       }
 
-      return value;
+      if (options.convert && typeof value === 'string') {
+        try {
+          const parsed = JSON.parse(value);
+          if (isPlainObject(parsed)) {
+            return parsed;
+          }
+          return this.createError('object.base', { value: parsed }, state, options);
+        } catch (e) {
+          return this.createError('object.parse', { value }, state, options);
+        }
+      }
+
+      return this.createError('object.base', { value }, state, options);
     },
     rules: [anyCustomRule],
   },
@@ -263,9 +274,23 @@ export const internals = Joi.extend([
     name: 'map',
 
     coerce(value: any, state: State, options: ValidationOptions) {
+      if (value === undefined) {
+        return value;
+      }
       if (isPlainObject(value)) {
         return new Map(Object.entries(value));
       }
+      if (options.convert && typeof value === 'string') {
+        try {
+          const parsed = JSON.parse(value);
+          if (isPlainObject(parsed)) {
+            return new Map(Object.entries(parsed));
+          }
+          return this.createError('map.base', { value: parsed }, state, options);
+        } catch (e) {
+          return this.createError('map.parse', { value }, state, options);
+        }
+      }
 
       return value;
     },
@@ -321,11 +346,23 @@ export const internals = Joi.extend([
   {
     name: 'record',
     pre(value: any, state: State, options: ValidationOptions) {
-      if (!isPlainObject(value)) {
-        return this.createError('record.base', { value }, state, options);
+      if (value === undefined || isPlainObject(value)) {
+        return value;
       }
 
-      return value as any;
+      if (options.convert && typeof value === 'string') {
+        try {
+          const parsed = JSON.parse(value);
+          if (isPlainObject(parsed)) {
+            return parsed;
+          }
+          return this.createError('record.base', { value: parsed }, state, options);
+        } catch (e) {
+          return this.createError('record.parse', { value }, state, options);
+        }
+      }
+
+      return this.createError('record.base', { value }, state, options);
     },
     rules: [
       anyCustomRule,
@@ -371,12 +408,23 @@ export const internals = Joi.extend([
 
     base: Joi.array(),
     coerce(value: any, state: State, options: ValidationOptions) {
-      // If value isn't defined, let Joi handle default value if it's defined.
-      if (value !== undefined && !Array.isArray(value)) {
-        return this.createError('array.base', { value }, state, options);
+      if (value === undefined || Array.isArray(value)) {
+        return value;
       }
 
-      return value;
+      if (options.convert && typeof value === 'string') {
+        try {
+          const parsed = JSON.parse(value);
+          if (Array.isArray(parsed)) {
+            return parsed;
+          }
+          return this.createError('array.base', { value: parsed }, state, options);
+        } catch (e) {
+          return this.createError('array.parse', { value }, state, options);
+        }
+      }
+
+      return this.createError('array.base', { value }, state, options);
     },
     rules: [anyCustomRule],
   },

packages/kbn-config-schema/src/types/__snapshots__/array_type.test.ts.snap

@@ -1,19 +0,0 @@
-// Jest Snapshot v1, https://goo.gl/fbAQLP
-
-exports[`#maxSize returns error when more items 1`] = `"array size is [2], but cannot be greater than [1]"`;
-
-exports[`#minSize returns error when fewer items 1`] = `"array size is [1], but cannot be smaller than [2]"`;
-
-exports[`fails for null values if optional 1`] = `"[0]: expected value of type [string] but got [null]"`;
-
-exports[`fails if mixed types of content in array 1`] = `"[2]: expected value of type [string] but got [boolean]"`;
-
-exports[`fails if wrong input type 1`] = `"expected value of type [array] but got [string]"`;
-
-exports[`fails if wrong type of content in array 1`] = `"[0]: expected value of type [string] but got [number]"`;
-
-exports[`includes namespace in failure when wrong item type 1`] = `"[foo-namespace.0]: expected value of type [string] but got [number]"`;
-
-exports[`includes namespace in failure when wrong top-level type 1`] = `"[foo-namespace]: expected value of type [array] but got [string]"`;
-
-exports[`object within array with required 1`] = `"[0.foo]: expected value of type [string] but got [undefined]"`;

packages/kbn-config-schema/src/types/__snapshots__/map_of_type.test.ts.snap

@@ -1,11 +0,0 @@
-// Jest Snapshot v1, https://goo.gl/fbAQLP
-
-exports[`fails when not receiving expected key type 1`] = `"[key(\\"name\\")]: expected value of type [number] but got [string]"`;
-
-exports[`fails when not receiving expected value type 1`] = `"[name]: expected value of type [string] but got [number]"`;
-
-exports[`includes namespace in failure when wrong key type 1`] = `"[foo-namespace.key(\\"name\\")]: expected value of type [number] but got [string]"`;
-
-exports[`includes namespace in failure when wrong top-level type 1`] = `"[foo-namespace]: expected value of type [Map] or [object] but got [Array]"`;
-
-exports[`includes namespace in failure when wrong value type 1`] = `"[foo-namespace.name]: expected value of type [string] but got [number]"`;

packages/kbn-config-schema/src/types/__snapshots__/object_type.test.ts.snap

@@ -1,24 +0,0 @@
-// Jest Snapshot v1, https://goo.gl/fbAQLP
-
-exports[`allowUnknowns = true affects only own keys 1`] = `"[foo.baz]: definition for this key is missing"`;
-
-exports[`called with wrong type 1`] = `"expected a plain object value, but found [string] instead."`;
-
-exports[`called with wrong type 2`] = `"expected a plain object value, but found [number] instead."`;
-
-exports[`does not allow unknown keys when allowUnknowns = false 1`] = `"[bar]: definition for this key is missing"`;
-
-exports[`fails if key does not exist in schema 1`] = `"[bar]: definition for this key is missing"`;
-
-exports[`fails if missing required value 1`] = `"[name]: expected value of type [string] but got [undefined]"`;
-
-exports[`handles oneOf 1`] = `
-"[key]: types that failed validation:
-- [key.0]: expected value of type [string] but got [number]"
-`;
-
-exports[`includes namespace in failure when wrong top-level type 1`] = `"[foo-namespace]: expected a plain object value, but found [Array] instead."`;
-
-exports[`includes namespace in failure when wrong value type 1`] = `"[foo-namespace.foo]: expected value of type [string] but got [number]"`;
-
-exports[`object within object with required 1`] = `"[foo.bar]: expected value of type [string] but got [undefined]"`;

packages/kbn-config-schema/src/types/array_type.test.ts

@@ -24,29 +24,65 @@ test('returns value if it matches the type', () => {
   expect(type.validate(['foo', 'bar', 'baz'])).toEqual(['foo', 'bar', 'baz']);
 });
 
+test('properly parse the value if input is a string', () => {
+  const type = schema.arrayOf(schema.string());
+  expect(type.validate('["foo", "bar", "baz"]')).toEqual(['foo', 'bar', 'baz']);
+});
+
 test('fails if wrong input type', () => {
   const type = schema.arrayOf(schema.string());
-  expect(() => type.validate('test')).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate(12)).toThrowErrorMatchingInlineSnapshot(
+    `"expected value of type [array] but got [number]"`
+  );
+});
+
+test('fails if string input cannot be parsed', () => {
+  const type = schema.arrayOf(schema.string());
+  expect(() => type.validate('test')).toThrowErrorMatchingInlineSnapshot(
+    `"could not parse array value from [test]"`
+  );
+});
+
+test('fails with correct type if parsed input is not an array', () => {
+  const type = schema.arrayOf(schema.string());
+  expect(() => type.validate('{"foo": "bar"}')).toThrowErrorMatchingInlineSnapshot(
+    `"expected value of type [array] but got [Object]"`
+  );
 });
 
 test('includes namespace in failure when wrong top-level type', () => {
   const type = schema.arrayOf(schema.string());
-  expect(() => type.validate('test', {}, 'foo-namespace')).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate('test', {}, 'foo-namespace')).toThrowErrorMatchingInlineSnapshot(
+    `"[foo-namespace]: could not parse array value from [test]"`
+  );
 });
 
 test('includes namespace in failure when wrong item type', () => {
   const type = schema.arrayOf(schema.string());
-  expect(() => type.validate([123], {}, 'foo-namespace')).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate([123], {}, 'foo-namespace')).toThrowErrorMatchingInlineSnapshot(
+    `"[foo-namespace.0]: expected value of type [string] but got [number]"`
+  );
 });
 
 test('fails if wrong type of content in array', () => {
   const type = schema.arrayOf(schema.string());
-  expect(() => type.validate([1, 2, 3])).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate([1, 2, 3])).toThrowErrorMatchingInlineSnapshot(
+    `"[0]: expected value of type [string] but got [number]"`
+  );
+});
+
+test('fails when parsing if wrong type of content in array', () => {
+  const type = schema.arrayOf(schema.string());
+  expect(() => type.validate('[1, 2, 3]')).toThrowErrorMatchingInlineSnapshot(
+    `"[0]: expected value of type [string] but got [number]"`
+  );
 });
 
 test('fails if mixed types of content in array', () => {
   const type = schema.arrayOf(schema.string());
-  expect(() => type.validate(['foo', 'bar', true, {}])).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate(['foo', 'bar', true, {}])).toThrowErrorMatchingInlineSnapshot(
+    `"[2]: expected value of type [string] but got [boolean]"`
+  );
 });
 
 test('returns empty array if input is empty but type has default value', () => {
@@ -61,7 +97,9 @@ test('returns empty array if input is empty even if type is required', () => {
 
 test('fails for null values if optional', () => {
   const type = schema.arrayOf(schema.maybe(schema.string()));
-  expect(() => type.validate([null])).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate([null])).toThrowErrorMatchingInlineSnapshot(
+    `"[0]: expected value of type [string] but got [null]"`
+  );
 });
 
 test('handles default values for undefined values', () => {
@@ -108,7 +146,9 @@ test('object within array with required', () => {
 
   const value = [{}];
 
-  expect(() => type.validate(value)).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate(value)).toThrowErrorMatchingInlineSnapshot(
+    `"[0.foo]: expected value of type [string] but got [undefined]"`
+  );
 });
 
 describe('#minSize', () => {
@@ -119,7 +159,7 @@ describe('#minSize', () => {
   test('returns error when fewer items', () => {
     expect(() =>
       schema.arrayOf(schema.string(), { minSize: 2 }).validate(['foo'])
-    ).toThrowErrorMatchingSnapshot();
+    ).toThrowErrorMatchingInlineSnapshot(`"array size is [1], but cannot be smaller than [2]"`);
   });
 });
 
@@ -131,6 +171,6 @@ describe('#maxSize', () => {
   test('returns error when more items', () => {
     expect(() =>
       schema.arrayOf(schema.string(), { maxSize: 1 }).validate(['foo', 'bar'])
-    ).toThrowErrorMatchingSnapshot();
+    ).toThrowErrorMatchingInlineSnapshot(`"array size is [2], but cannot be greater than [1]"`);
   });
 });

packages/kbn-config-schema/src/types/array_type.ts

@@ -49,6 +49,8 @@ export class ArrayType<T> extends Type<T[]> {
       case 'any.required':
       case 'array.base':
         return `expected value of type [array] but got [${typeDetect(value)}]`;
+      case 'array.parse':
+        return `could not parse array value from [${value}]`;
       case 'array.min':
         return `array size is [${value.length}], but cannot be smaller than [${limit}]`;
       case 'array.max':

packages/kbn-config-schema/src/types/map_of_type.test.ts

@@ -29,13 +29,46 @@ test('handles object as input', () => {
   expect(type.validate(value)).toEqual(expected);
 });
 
+test('properly parse the value if input is a string', () => {
+  const type = schema.mapOf(schema.string(), schema.string());
+  const value = `{"name": "foo"}`;
+  const expected = new Map([['name', 'foo']]);
+
+  expect(type.validate(value)).toEqual(expected);
+});
+
+test('fails if string input cannot be parsed', () => {
+  const type = schema.mapOf(schema.string(), schema.string());
+  expect(() => type.validate(`invalidjson`)).toThrowErrorMatchingInlineSnapshot(
+    `"could not parse map value from [invalidjson]"`
+  );
+});
+
+test('fails with correct type if parsed input is not an object', () => {
+  const type = schema.mapOf(schema.string(), schema.string());
+  expect(() => type.validate('[1,2,3]')).toThrowErrorMatchingInlineSnapshot(
+    `"expected value of type [Map] or [object] but got [Array]"`
+  );
+});
+
 test('fails when not receiving expected value type', () => {
   const type = schema.mapOf(schema.string(), schema.string());
   const value = {
     name: 123,
   };
 
-  expect(() => type.validate(value)).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate(value)).toThrowErrorMatchingInlineSnapshot(
+    `"[name]: expected value of type [string] but got [number]"`
+  );
+});
+
+test('fails after parsing when not receiving expected value type', () => {
+  const type = schema.mapOf(schema.string(), schema.string());
+  const value = `{"name": 123}`;
+
+  expect(() => type.validate(value)).toThrowErrorMatchingInlineSnapshot(
+    `"[name]: expected value of type [string] but got [number]"`
+  );
 });
 
 test('fails when not receiving expected key type', () => {
@@ -44,12 +77,25 @@ test('fails when not receiving expected key type', () => {
     name: 'foo',
   };
 
-  expect(() => type.validate(value)).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate(value)).toThrowErrorMatchingInlineSnapshot(
+    `"[key(\\"name\\")]: expected value of type [number] but got [string]"`
+  );
+});
+
+test('fails after parsing when not receiving expected key type', () => {
+  const type = schema.mapOf(schema.number(), schema.string());
+  const value = `{"name": "foo"}`;
+
+  expect(() => type.validate(value)).toThrowErrorMatchingInlineSnapshot(
+    `"[key(\\"name\\")]: expected value of type [number] but got [string]"`
+  );
 });
 
 test('includes namespace in failure when wrong top-level type', () => {
   const type = schema.mapOf(schema.string(), schema.string());
-  expect(() => type.validate([], {}, 'foo-namespace')).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate([], {}, 'foo-namespace')).toThrowErrorMatchingInlineSnapshot(
+    `"[foo-namespace]: expected value of type [Map] or [object] but got [Array]"`
+  );
 });
 
 test('includes namespace in failure when wrong value type', () => {
@@ -58,7 +104,9 @@ test('includes namespace in failure when wrong value type', () => {
     name: 123,
   };
 
-  expect(() => type.validate(value, {}, 'foo-namespace')).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate(value, {}, 'foo-namespace')).toThrowErrorMatchingInlineSnapshot(
+    `"[foo-namespace.name]: expected value of type [string] but got [number]"`
+  );
 });
 
 test('includes namespace in failure when wrong key type', () => {
@@ -67,7 +115,9 @@ test('includes namespace in failure when wrong key type', () => {
     name: 'foo',
   };
 
-  expect(() => type.validate(value, {}, 'foo-namespace')).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate(value, {}, 'foo-namespace')).toThrowErrorMatchingInlineSnapshot(
+    `"[foo-namespace.key(\\"name\\")]: expected value of type [number] but got [string]"`
+  );
 });
 
 test('returns default value if undefined', () => {

packages/kbn-config-schema/src/types/map_type.ts

@@ -48,6 +48,8 @@ export class MapOfType<K, V> extends Type<Map<K, V>> {
       case 'any.required':
       case 'map.base':
         return `expected value of type [Map] or [object] but got [${typeDetect(value)}]`;
+      case 'map.parse':
+        return `could not parse map value from [${value}]`;
       case 'map.key':
       case 'map.value':
         const childPathWithIndex = path.slice();

packages/kbn-config-schema/src/types/object_type.test.ts

@@ -30,13 +30,42 @@ test('returns value by default', () => {
   expect(type.validate(value)).toEqual({ name: 'test' });
 });
 
+test('properly parse the value if input is a string', () => {
+  const type = schema.object({
+    name: schema.string(),
+  });
+  const value = `{"name": "test"}`;
+
+  expect(type.validate(value)).toEqual({ name: 'test' });
+});
+
+test('fails if string input cannot be parsed', () => {
+  const type = schema.object({
+    name: schema.string(),
+  });
+  expect(() => type.validate(`invalidjson`)).toThrowErrorMatchingInlineSnapshot(
+    `"could not parse object value from [invalidjson]"`
+  );
+});
+
+test('fails with correct type if parsed input is not an object', () => {
+  const type = schema.object({
+    name: schema.string(),
+  });
+  expect(() => type.validate('[1,2,3]')).toThrowErrorMatchingInlineSnapshot(
+    `"expected a plain object value, but found [Array] instead."`
+  );
+});
+
 test('fails if missing required value', () => {
   const type = schema.object({
     name: schema.string(),
   });
   const value = {};
 
-  expect(() => type.validate(value)).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate(value)).toThrowErrorMatchingInlineSnapshot(
+    `"[name]: expected value of type [string] but got [undefined]"`
+  );
 });
 
 test('returns value if undefined string with default', () => {
@@ -57,7 +86,9 @@ test('fails if key does not exist in schema', () => {
     foo: 'bar',
   };
 
-  expect(() => type.validate(value)).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate(value)).toThrowErrorMatchingInlineSnapshot(
+    `"[bar]: definition for this key is missing"`
+  );
 });
 
 test('defined object within object', () => {
@@ -96,7 +127,9 @@ test('object within object with required', () => {
   });
   const value = { foo: {} };
 
-  expect(() => type.validate(value)).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate(value)).toThrowErrorMatchingInlineSnapshot(
+    `"[foo.bar]: expected value of type [string] but got [undefined]"`
+  );
 });
 
 describe('#validate', () => {
@@ -127,8 +160,12 @@ describe('#validate', () => {
 test('called with wrong type', () => {
   const type = schema.object({});
 
-  expect(() => type.validate('foo')).toThrowErrorMatchingSnapshot();
-  expect(() => type.validate(123)).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate('foo')).toThrowErrorMatchingInlineSnapshot(
+    `"could not parse object value from [foo]"`
+  );
+  expect(() => type.validate(123)).toThrowErrorMatchingInlineSnapshot(
+    `"expected a plain object value, but found [number] instead."`
+  );
 });
 
 test('handles oneOf', () => {
@@ -137,7 +174,10 @@ test('handles oneOf', () => {
   });
 
   expect(type.validate({ key: 'foo' })).toEqual({ key: 'foo' });
-  expect(() => type.validate({ key: 123 })).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate({ key: 123 })).toThrowErrorMatchingInlineSnapshot(`
+"[key]: types that failed validation:
+- [key.0]: expected value of type [string] but got [number]"
+`);
 });
 
 test('handles references', () => {
@@ -186,7 +226,9 @@ test('includes namespace in failure when wrong top-level type', () => {
     foo: schema.string(),
   });
 
-  expect(() => type.validate([], {}, 'foo-namespace')).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate([], {}, 'foo-namespace')).toThrowErrorMatchingInlineSnapshot(
+    `"[foo-namespace]: expected a plain object value, but found [Array] instead."`
+  );
 });
 
 test('includes namespace in failure when wrong value type', () => {
@@ -197,7 +239,9 @@ test('includes namespace in failure when wrong value type', () => {
     foo: 123,
   };
 
-  expect(() => type.validate(value, {}, 'foo-namespace')).toThrowErrorMatchingSnapshot();
+  expect(() => type.validate(value, {}, 'foo-namespace')).toThrowErrorMatchingInlineSnapshot(
+    `"[foo-namespace.foo]: expected value of type [string] but got [number]"`
+  );
 });
 
 test('individual keys can validated', () => {
@@ -241,7 +285,7 @@ test('allowUnknowns = true affects only own keys', () => {
         baz: 'baz',
       },
     })
-  ).toThrowErrorMatchingSnapshot();
+  ).toThrowErrorMatchingInlineSnapshot(`"[foo.baz]: definition for this key is missing"`);
 });
 
 test('does not allow unknown keys when allowUnknowns = false', () => {
@@ -253,5 +297,5 @@ test('does not allow unknown keys when allowUnknowns = false', () => {
     type.validate({
       bar: 'baz',
     })
-  ).toThrowErrorMatchingSnapshot();
+  ).toThrowErrorMatchingInlineSnapshot(`"[bar]: definition for this key is missing"`);
 });

packages/kbn-config-schema/src/types/object_type.ts

@@ -61,6 +61,8 @@ export class ObjectType<P extends Props = any> extends Type<ObjectResultType<P>>
       case 'any.required':
       case 'object.base':
         return `expected a plain object value, but found [${typeDetect(value)}] instead.`;
+      case 'object.parse':
+        return `could not parse object value from [${value}]`;
       case 'object.allowUnknown':
         return `definition for this key is missing`;
       case 'object.child':

packages/kbn-config-schema/src/types/one_of_type.test.ts

@@ -138,7 +138,7 @@ test('fails if nested union type fail', () => {
  - [0]: expected value of type [boolean] but got [string]
 - [1]: types that failed validation:
  - [0]: types that failed validation:
-  - [0]: expected a plain object value, but found [string] instead.
+  - [0]: could not parse object value from [aaa]
   - [1]: expected value of type [number] but got [string]"
 `);
 });

packages/kbn-config-schema/src/types/record_of_type.test.ts

@@ -27,6 +27,20 @@ test('handles object as input', () => {
   expect(type.validate(value)).toEqual({ name: 'foo' });
 });
 
+test('properly parse the value if input is a string', () => {
+  const type = schema.recordOf(schema.string(), schema.string());
+  const value = `{"name": "foo"}`;
+  expect(type.validate(value)).toEqual({ name: 'foo' });
+});
+
+test('fails with correct type if parsed input is a plain object', () => {
+  const type = schema.recordOf(schema.string(), schema.string());
+  const value = `["a", "b"]`;
+  expect(() => type.validate(value)).toThrowErrorMatchingInlineSnapshot(
+    `"expected value of type [object] but got [Array]"`
+  );
+});
+
 test('fails when not receiving expected value type', () => {
   const type = schema.recordOf(schema.string(), schema.string());
   const value = {
@@ -38,6 +52,15 @@ test('fails when not receiving expected value type', () => {
   );
 });
 
+test('fails after parsing when not receiving expected value type', () => {
+  const type = schema.recordOf(schema.string(), schema.string());
+  const value = `{"name": 123}`;
+
+  expect(() => type.validate(value)).toThrowErrorMatchingInlineSnapshot(
+    `"[name]: expected value of type [string] but got [number]"`
+  );
+});
+
 test('fails when not receiving expected key type', () => {
   const type = schema.recordOf(
     schema.oneOf([schema.literal('nickName'), schema.literal('lastName')]),
@@ -55,6 +78,21 @@ test('fails when not receiving expected key type', () => {
 `);
 });
 
+test('fails after parsing when not receiving expected key type', () => {
+  const type = schema.recordOf(
+    schema.oneOf([schema.literal('nickName'), schema.literal('lastName')]),
+    schema.string()
+  );
+
+  const value = `{"name": "foo"}`;
+
+  expect(() => type.validate(value)).toThrowErrorMatchingInlineSnapshot(`
+"[key(\\"name\\")]: types that failed validation:
+- [0]: expected value to equal [nickName] but got [name]
+- [1]: expected value to equal [lastName] but got [name]"
+`);
+});
+
 test('includes namespace in failure when wrong top-level type', () => {
   const type = schema.recordOf(schema.string(), schema.string());
   expect(() => type.validate([], {}, 'foo-namespace')).toThrowErrorMatchingInlineSnapshot(

packages/kbn-config-schema/src/types/record_type.ts

@@ -40,6 +40,8 @@ export class RecordOfType<K extends string, V> extends Type<Record<K, V>> {
       case 'any.required':
       case 'record.base':
         return `expected value of type [object] but got [${typeDetect(value)}]`;
+      case 'record.parse':
+        return `could not parse record value from [${value}]`;
       case 'record.key':
       case 'record.value':
         const childPathWithIndex = path.slice();

x-pack/plugins/actions/server/builtin_action_types/es_index.test.ts

@@ -150,7 +150,7 @@ describe('params validation', () => {
     expect(() => {
       validateParams(actionType, { documents: ['should be an object'] });
     }).toThrowErrorMatchingInlineSnapshot(
-      `"error validating action params: [documents.0]: expected value of type [object] but got [string]"`
+      `"error validating action params: [documents.0]: could not parse record value from [should be an object]"`
     );
   });
 });

x-pack/plugins/actions/server/builtin_action_types/webhook.test.ts

@@ -130,7 +130,7 @@ describe('config validation', () => {
       validateConfig(actionType, config);
     }).toThrowErrorMatchingInlineSnapshot(`
 "error validating action type config: [headers]: types that failed validation:
-- [headers.0]: expected value of type [object] but got [string]
+- [headers.0]: could not parse record value from [application/json]
 - [headers.1]: expected value to equal [null] but got [application/json]"
 `);
   });

x-pack/plugins/spaces/server/lib/space_schema.test.ts

@@ -93,7 +93,7 @@ describe('#disabledFeatures', () => {
         disabledFeatures: 'foo',
       })
     ).toThrowErrorMatchingInlineSnapshot(
-      `"[disabledFeatures]: expected value of type [array] but got [string]"`
+      `"[disabledFeatures]: could not parse array value from [foo]"`
     );
   });
 

x-pack/test/api_integration/apis/management/rollup/index_patterns_extensions.js

@@ -79,7 +79,7 @@ export default function({ getService }) {
           uri = `${BASE_URI}?${querystring.stringify(params)}`;
           ({ body } = await supertest.get(uri).expect(400));
           expect(body.message).to.contain(
-            '[request query.meta_fields]: expected value of type [array]'
+            '[request query.meta_fields]: could not parse array value from [stringValue]'
           );
         });