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Koa.js 自定义POST请求参数验证中间件

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  1. 用例
  2. 源码

用例

用于验证POST或GET请求参数是否满足要求，用例如下：

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const validate = require('validate.js');
const Koa = require('Koa');
const app = new Koa();

// 数组形式
app.use(validate(['account', 'password']));

// 键值对形式：值为 Boolean
app.use(validate({account: true, password: true}));

// 键值对形式：在值中指定类型、是否必要、取值等
app.use(validate({
    account: {required: true, type: 'string'},
    password: {required: true, type: 'string'},
    num: {required: true, type: 'number', values: [0,1,2]} 
}));

app.listen(3000);

源码

validate.js

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const logger = require('../../utils/logger').logger;
const chalk = require('chalk');

if (!String.prototype.t) {
    String.prototype.t = function(...args) {
        if (args.length === 0) {
            return this.toString();
        }

        const template = '%t';
        let str = this.toString();

        for (let i = 0; i < args.length; i++) {
            let idx = str.indexOf(template);
            if (idx === -1) break;
            if (typeof args[i] === 'object') {
                args[i] = JSON.stringify(args[i]);
            }
            str = str.substr(0, idx) + args[i] +
                str.substring(idx + template.length, str.length);
        }
        return str;
    }
}

/**
 * 参数验证中间件：针对post验证body，针对get验证query
 * @param {string[]|{}} rules 验证规则
 * @example
 * validate(['account', 'password'])
 * validate({account: true, password: true})
 * validate({
 *     account: {required: true, type: 'string'},
 *     password: {required: true, type: 'string'},
 *     num: {required: true, type: 'number', values: [0,1,2]} 
 * })
 * @returns {Function} Koa中间件函数
 */
const validate = (rules) => {
    let m_logger = console;
    if (logger && logger.isInitiatial()) {
        m_logger = logger;
    }
    return async(ctx, next) => {
        const method = ctx.request.method;

        if (method !== 'POST' && method !== 'GET') {
            console.error(`Warning: Cannot validate except from POST and GET method`);
            return next();
        }

        const obj = method === 'POST' ?
            ctx.request.body :
            ctx.request.query;

        if (!obj) {
            if (method === 'POST') throw new Error('POST body is null');
            else if (method === 'GET') throw new Error('Query parameter is null');
            else throw new Error('Object is null');
        }

        if (!rules)
            return next();


        /**
         * 定义异常处理函数 
         */

        const ParaMissingFunc = (key, obj) => {
            const errMsg = 'Missing [%t] Parameter: [%t]';
            return ctx.throw(403, errMsg.t(chalk.yellow(method), chalk.cyan(key)));
        };
        const ParaTypeErrFunc = (key, obj, ruleType) => {
            const errMsg = 'Type error of Parameter: [%t] ( require [%t] )';
            return ctx.throw(403, errMsg.t(chalk.yellow(key), chalk.cyan(ruleType)));
        };
        const InvalidParaValueErrFunc = (key, obj) => {
            const errMsg = 'Invalid parameter value: %t';
            return ctx.throw(403, errMsg.t(chalk.cyan(obj[key])));
        }

        if (Array.isArray(rules)) {
            for (let key of rules) {
                if (obj[key] === undefined) {
                    return ParaMissingFunc(key, obj);
                }
            }
            return next();
        } else if (typeof rules === 'object') {
            for (let key in rules) {
                const rule = rules[key];
                if (typeof rule === 'boolean') {
                    if (rule === true && obj[key] === undefined) {
                        return ParaMissingFunc(key, obj);
                    }
                } else if (typeof rule === 'object') {
                    if (rule.required !== undefined && rule.required === true) {
                        if (obj[key] === undefined) {
                            return ParaMissingFunc(key, obj);
                        }
                    }

                    if (rule.type !== undefined) {
                        if (typeof obj[key] !== rule.type) {
                            return ParaTypeErrFunc(key, obj, rule.type);
                        }
                    }

                    if (Array.isArray(rule.values)) {
                        if (rule.values.indexOf(obj[key]) === -1) {
                            return InvalidParaValueErrFunc(key, obj);
                        }
                    }
                } else {
                    throw new Error(`Unexpected rule type: ${typeof rule} - (  key [${key}] in ${JSON.stringify(rules)}  )`);
                }
            }
            await next();
        } else {
            throw new Error('Invalid rules type: ' + typeof rules);
        }
    }
};

module.exports = validate;
  • logger是日志中间件，可替换为console
  • chalk用于给控制台输出上色
  • String.prototype.t用于格式化字符串，如：
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const str = '%t, %t'.t(1, 2);   // str == '1, 2'