使用ajv-errors生成json-schema错误信息

使用 ajv-errors 生成 json-schema 错误信息

ajv-errors 给 Json-schema 添加了一个errorMessage关键字,通过这个关键字来输出错误信息

const Ajv = require('ajv')
const ajv = new Ajv({ allErrors: true, jsonPointers: true })
require('ajv-errors')(ajv)
//一个json schema规范的对象
const schema = {}
//待校验的json对象
const data = {}
const validate = ajv.compile(schema)
validate(data) //返回boolean，是否校验通过
validate.errors //错误详细信息

用法

  1. 单个错误信息

    用一条消息替换当前 schema 和 sub schema 中的所有错误

    var schema = {
    type: 'object',
    required: ['foo'],
    properties: {
    foo: { type: 'integer' }
    },
    additionalProperties: false,
    errorMessage: 'should be an object with an integer property foo only'
    };

  2. 关键字错误

    var schema = {
    type: 'object',
    required: ['foo'],
    properties: {
    foo: { type: 'integer' }
    },
    additionalProperties: false,
    errorMessage: {
    type: 'should be an object', // will not replace internal "type" error for the property "foo"
    required: 'should have property foo',
    additionalProperties: 'should not have properties other than foo'
    }
    };

    required和dependencies可以使用对象指定特定的属性的错误信息。示例如下：

    var schema = {
    type: 'object',
    required: ['foo', 'bar'],
    properties: {
    foo: { type: 'integer' },
    bar: { type: 'string' }
    },
    errorMessage: {
    type: 'should be an object', // will not replace internal "type" error for the property "foo"
    required: {
    foo: 'should have an integer property "foo"',
    bar: 'should have a string property "bar"'
    }
    }
    };

  3. 属性的错误信息

    无论属性是在哪里创建的

    var schema = {
    type: 'object',
    required: ['foo', 'bar'],
    allOf: [{
    properties: {
    foo: { type: 'integer', minimum: 2 },
    bar: { type: 'string', minLength: 2 }
    },
    additionalProperties: false
    }],
    errorMessage: {
    properties: {
    foo: 'data.foo should be integer >= 2',
    bar: 'data.bar should be string with length >= 2'
    }
    }
    };

  4. 默认错误信息

    当 errorMessage 是一个对象时，可以指定一个默认错误来兜底错误。

    var schema = {
    type: 'object',
    required: ['foo', 'bar'],
    allOf: [{
    properties: {
    foo: { type: 'integer', minimum: 2 },
    bar: { type: 'string', minLength: 2 }
    },
    additionalProperties: false
    }],
    errorMessage: {
    type: 'data should be an object',
    properties: {
    foo: 'data.foo should be integer >= 2',
    bar: 'data.bar should be string with length >= 2'
    },
    _: 'data should have properties "foo" and "bar" only'
    }
    };

  5. 模板语法

    配合 json pointer 可以展示当前 json 的实际值

    var schema = {
    "type": "object",
    "properties": {
    "size": {
    "type": "number",
    "minimum": 4
    }
    },
    "errorMessage": {
    "properties": {
    "size": "size should be a number bigger or equal to 4, current value is ${/size}"
    }
    }
    }

validate({size:1}) //validate.error 是个对象。其中会有错误信息如下。error 具体结构参考https://www.npmjs.com/package/ajv-errors //"size should be a number bigger or equal to 4, current value is 1"

可以将 minimum 设置成一个变量，然后 errorMessage 配合变量和 es6 模板字符串达到改变变量，自动更改校验提示。
注意：json pointer 需要使用\转义
```json
//同上一个校验
const minimum = 4
var schema = {
"type": "object",
"properties": {
"size": {
"type": "number",
minimum
}
},
"errorMessage": {
"properties": {
"size": `size should be a number bigger or equal to ${minimum}, current value is \${/size}`
}
}
}

参考

  1. ajv-errors readme
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