decorator-x/src/transform/entity/flow/flow.js

decorator for entity instantiation & validation, auto-generate swagger docs & graphql schema

// @flow

const fs = require('fs');
const { promisify } = require('util');
const readFileAsync = promisify(fs.readFile); // (A)

const babel = require('babel-core');

import {
  extractFlowTypeFromClassProperty,
  generateDecoratorWithObjectParams,
  generateImportDeclaration
} from '../../../internal/babel/ast';

export function flowToDecoratorPlugin(babel) {
  const { types: t } = babel;

  return {
    name: 'flow-to-decorator-ast-transform', // not required
    visitor: {
      Program(path) {
        // 添加头部导入库
        path.node.body.splice(
          0,
          0,
          generateImportDeclaration('{ entityProperty }', 'swagger-decorator')
        );
      },

      ClassProperty(path, state) {
        // 判断当前是否已经存在注解，如果不存在则动态创建
        if (!path.node.decorators) {
          let typeAndValue = extractFlowTypeFromClassProperty(path.node);

          path.node.decorators = [
            generateDecoratorWithObjectParams(
              'entityProperty',
              {
                type: typeAndValue.type,
                required: typeAndValue.value === 'undefined'
              },
              typeAndValue.comment
            )
          ];
        }
      }
    }
  };
}

/**
 * Description 执行 Babel 转换过程
 * @param fileName
 * @param destFileName
 * @returns {Promise.<void>}
 */
export async function flowToDecorator(
  fileName: string,
  destFileName: string = undefined
) {
  let codeStr = (await readFileAsync(fileName)).toString();

  // 使用自定义插件进行转化
  const out = babel.transform(codeStr, {
    plugins: [
      'syntax-flow',
      'syntax-class-properties',
      'syntax-decorators',
      flowToDecoratorPlugin
    ]
  });

  if (destFileName) {
    fs.writeFileSync(destFileName, out.code);
  }

  return out.code;
}