introduce: keyword errorMessages for custom local error messages

Author: sagold

README.md

@@ -1214,6 +1214,22 @@ const myDraft = extendDraft(draft2020, {
 });
 ```
 
+### errors
+
+You can set custom errors messages locally by using the errors-keyword:
+
+```ts
+const { errors } = compileSchema({
+    type: "array",
+    minItems: 2,
+    errorMessages: {
+        "min-items-error": "Custom error {{minItems}}"
+    }
+}).validate([1]);
+
+assert.deepEqual(errors[0].message, "Custom error 2");
+```
+
 ## Breaking Changes
 
 ### v10.0.0

src/SchemaNode.ts

@@ -221,7 +221,7 @@ export const SchemaNodeMethods = {
     createError<T extends string = DefaultErrors>(code: T, data: ErrorData, message?: string): JsonError {
         let errorMessage = message;
         if (errorMessage === undefined) {
-            const error = this.context.errors[code];
+            const error = this.schema?.errorMessages?.[code] ?? this.context.errors[code];
             if (typeof error === "function") {
                 return error(data);
             }

src/compileSchema.validate.test.ts

@@ -1004,3 +1004,35 @@ describe("compileSchema.validate - errorsAsync", () => {
         });
     });
 });
+
+describe("compileSchema.validate - custom errors", () => {
+    it("should return custom error message for minItems", () => {
+        const { errors } = compileSchema({
+            type: "array",
+            minItems: 2,
+            errorMessages: {
+                "min-items-error": "Custom error {{minItems}}"
+            }
+        }).validate([1]);
+        assert.deepEqual(errors.length, 1);
+        assert.deepEqual(errors[0].message, "Custom error 2");
+    });
+
+    it("should return custom error for oneOf-error", () => {
+        const { errors } = compileSchema({
+            type: "array",
+            items: {
+                errorMessages: {
+                    "one-of-error": "{{value}} does not match any of the options"
+                },
+                oneOf: [
+                    { type: "number" },
+                    { type: "object", properties: { a: { type: "string" } }, additionalProperties: false }
+                ]
+            },
+            additionalItems: false
+        }).validate([100, { a: "correct", b: "not correct" }]);
+        assert.deepEqual(errors.length, 1);
+        assert.deepEqual(errors[0].message, '{"a":"correct","b":"not correct"} does not match any of the options');
+    });
+});