319 lines
7.9 KiB
Markdown
319 lines
7.9 KiB
Markdown
# ajv-errors
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Custom error messages in JSON-Schema for Ajv validator
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[](https://travis-ci.org/epoberezkin/ajv-errors)
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[](http://badge.fury.io/js/ajv-errors)
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[](https://coveralls.io/github/epoberezkin/ajv-errors?branch=master)
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[](https://gitter.im/ajv-validator/ajv)
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## Contents
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- [Install](#install)
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- [Usage](#usage)
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- [Single message](#single-message)
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- [Messages for keywords](#messages-for-keywords)
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- [Messages for properties and items](#messages-for-properties-and-items)
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- [Default message](#default-message)
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- [Templates](#templates)
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- [Options](#options)
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- [License](#license)
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## Install
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```
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npm install ajv-errors
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```
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## Usage
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Add the keyword `errorMessages` to Ajv instance:
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```javascript
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var Ajv = require('ajv');
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var ajv = new Ajv({allErrors: true, jsonPointers: true});
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// Ajv options allErrors and jsonPointers are required
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require('ajv-errors')(ajv /*, {singleError: true} */);
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```
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See [Options](#options) below.
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### Single message
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Replace all errors in the current schema and subschemas with a single message:
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```javascript
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var schema = {
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type: 'object',
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required: ['foo'],
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properties: {
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foo: { type: 'integer' }
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},
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additionalProperties: false,
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errorMessage: 'should be an object with an integer property foo only'
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};
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var validate = ajv.compile(schema);
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console.log(validate({foo: 'a', bar: 2})); // false
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console.log(validate.errors); // processed errors
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```
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Processed errors:
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```javascript
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[
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{
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keyword: 'errorMessage',
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message: 'should be an object with an integer property foo only',
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// ...
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params: {
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errors: [
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{ keyword: 'additionalProperties', dataPath: '' /* , ... */ },
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{ keyword: 'type', dataPath: '.foo' /* , ... */ }
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]
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}
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}
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]
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```
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### Messages for keywords
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Replace errors for certain keywords in the current schema only:
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```javascript
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var schema = {
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type: 'object',
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required: ['foo'],
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properties: {
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foo: { type: 'integer' }
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},
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additionalProperties: false,
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errorMessage: {
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type: 'should be an object', // will not replace internal "type" error for the property "foo"
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required: 'should have property foo',
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additionalProperties: 'should not have properties other than foo'
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}
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};
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var validate = ajv.compile(schema);
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console.log(validate({foo: 'a', bar: 2})); // false
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console.log(validate.errors); // processed errors
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```
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Processed errors:
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```javascript
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[
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{
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// original error
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keyword: type,
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dataPath: '/foo',
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// ...
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message: 'should be integer'
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},
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{
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// generated error
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keyword: 'errorMessage',
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message: 'should not have properties other than foo',
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// ...
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params: {
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errors: [
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{ keyword: 'additionalProperties' /* , ... */ }
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]
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},
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}
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]
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```
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For keywords "required" and "dependencies" it is possible to specify different messages for different properties:
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```javascript
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var schema = {
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type: 'object',
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required: ['foo', 'bar'],
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properties: {
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foo: { type: 'integer' },
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bar: { type: 'string' }
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},
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errorMessage: {
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type: 'should be an object', // will not replace internal "type" error for the property "foo"
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required: {
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foo: 'should have an integer property "foo"',
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bar: 'should have a string property "bar"'
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}
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}
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};
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```
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### Messages for properties and items
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Replace errors for properties / items (and deeper), regardless where in schema they were created:
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```javascript
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var schema = {
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type: 'object',
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required: ['foo', 'bar'],
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allOf: [{
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properties: {
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foo: { type: 'integer', minimum: 2 },
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bar: { type: 'string', minLength: 2 }
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},
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additionalProperties: false
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}],
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errorMessage: {
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properties: {
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foo: 'data.foo should be integer >= 2',
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bar: 'data.bar should be string with length >= 2'
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}
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}
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};
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var validate = ajv.compile(schema);
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console.log(validate({foo: 1, bar: 'a'})); // false
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console.log(validate.errors); // processed errors
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```
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Processed errors:
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```javascript
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[
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{
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keyword: 'errorMessage',
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message: 'data.foo should be integer >= 2',
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dataPath: '/foo',
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// ...
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params: {
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errors: [
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{ keyword: 'minimum' /* , ... */ }
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]
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},
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},
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{
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keyword: 'errorMessage',
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message: 'data.bar should be string with length >= 2',
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dataPath: '/bar',
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// ...
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params: {
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errors: [
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{ keyword: 'minLength' /* , ... */ }
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]
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},
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}
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]
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```
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### Default message
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When the value of keyword `errorMessage` is an object you can specify a message that will be used if any error appears that is not specified by keywords/properties/items:
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```javascript
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var schema = {
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type: 'object',
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required: ['foo', 'bar'],
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allOf: [{
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properties: {
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foo: { type: 'integer', minimum: 2 },
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bar: { type: 'string', minLength: 2 }
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},
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additionalProperties: false
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}],
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errorMessage: {
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type: 'data should be an object',
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properties: {
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foo: 'data.foo should be integer >= 2',
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bar: 'data.bar should be string with length >= 2'
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},
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_: 'data should have properties "foo" and "bar" only'
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}
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};
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var validate = ajv.compile(schema);
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console.log(validate({})); // false
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console.log(validate.errors); // processed errors
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```
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Processed errors:
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```javascript
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[
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{
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keyword: 'errorMessage',
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message: 'data should be an object with properties "foo" and "bar" only',
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dataPath: '',
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// ...
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params: {
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errors: [
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{ keyword: 'required' /* , ... */ },
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{ keyword: 'required' /* , ... */ }
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]
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},
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}
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]
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```
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The message in property `_` of `errorMessage` replaces the same errors that would have been replaced if `errorMessage` were a string.
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## Templates
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Custom error messages used in `errorMessage` keyword can be templates using [JSON-pointers](https://tools.ietf.org/html/rfc6901) or [relative JSON-pointers](http://tools.ietf.org/html/draft-luff-relative-json-pointer-00) to data being validated, in which case the value will be interpolated. Also see [examples](https://gist.github.com/geraintluff/5911303) of relative JSON-pointers.
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The syntax to interpolate a value is `${<pointer>}`.
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The values used in messages will be JSON-stringified:
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- to differentiate between `false` and `"false"`, etc.
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- to support structured values.
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Example:
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```json
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{
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"type": "object",
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"properties": {
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"size": {
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"type": "number",
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"minimum": 4
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}
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},
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"errorMessage": {
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"properties": {
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"size": "size should be a number bigger or equal to 4, current value is ${/size}"
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}
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}
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}
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```
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## Options
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Defaults:
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```javascript
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{
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keepErrors: false,
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singleError: false
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}
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```
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- _keepErrors_: keep original errors. Default is to remove matched errors (they will still be available in `params.errors` property of generated error). If an error was matched and included in the error generated by `errorMessage` keyword it will have property `emUsed: true`.
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- _singleError_: create one error for all keywords used in `errorMessage` keyword (error messages defined for properties and items are not merged because they have different dataPaths). Multiple error messages are concatenated. Option values:
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- `false` (default): create multiple errors, one for each message
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- `true`: create single error, messages are concatenated using `"; "`
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- non-empty string: this string is used as a separator to concatenate messages
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## Supporters
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[<img src="https://media.licdn.com/mpr/mpr/shrinknp_400_400/AAEAAQAAAAAAAAwEAAAAJDg1YzBlYzFjLTA3YWYtNGEzOS1iMTdjLTQ0MTU1NWZjOGM0ZQ.jpg" width="48" height="48">](https://www.linkedin.com/in/rogerkepler/) [Roger Kepler](https://www.linkedin.com/in/rogerkepler/)
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## License
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[MIT](https://github.com/epoberezkin/ajv-errors/blob/master/LICENSE)
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