Question

我想静态创建一个yup模式（该模式定义一次），该模式每次调用时都会使用一个动态变量（每次调用的变量可能不同）。这可能吗？

例如

// file: schema.js
// create the schema once
yup = require('yup');
const schema = yup.mixed().test(
  'my-test-name',
  'cannot be an existing value',
  value => !myArray.includes(value)  // How to reference myArray here?
       // As written, it results in "ReferenceError: myArray is not defined"
);
module.exports = schema;



// other file that imports the schema:
schema = require('./schema.js');
let myArray = ['blue', 'green'];
schema.validateSync('yellow');  // should pass validation, because 'yellow' not in myArray

myArray = ['orange', 'yellow'];
schema.validateSync('yellow');  // should fail validation, because 'yellow' is in myArray

（我意识到有可能每次在该范围内使用变量来动态创建模式。但是，我正在使用具有许多静态定义的yup模式的代码库，该函数具有将模式映射到其对应字段的功能。我希望有一种方法能够将动态变量仅用于需要它们的几个模式，而不必将每个静态模式都修改为动态。）

Answer 1

尝试导出创建动态架构的函数。请参见下面。

// file: schema.js
// create the schema once
yup = require('yup');

// export as a function
module.exports = myArray => {
  return yup.mixed().test(
    'my-test-name',
    'cannot be an existing value',
    value => !myArray.includes(value)  
  );
};



// other file that imports the schema:
schema = require('./schema.js');
let myArray = ['blue', 'green'];

let blueGreenSchema = schema(myArray);
blueGreenSchema.validateSync('yellow');  

myArray = ['orange', 'yellow'];
let orangeYellowSchema = schema(myArray);
orangeYellowSchema.validateSync('yellow');

Answer 2

要使用动态变量，需要做三件事：

通过Options键将第二个validateSync()参数用于context
使用函数表达式而不是箭头函数声明.test()函数（因为yup将函数绑定到this）
在测试函数中，使用this.options.context.variableName引用动态变量

例如

const yup = require('yup');

// statically declare the schema
const schema = yup.mixed().test(
  'my-test-name',
  'cannot be an existing value',  // error message
  function test(value) {
    // NOTE: this must not be an arrow function, because yup binds it to it's "this"
    // Note the use of this.options.context to reference the dynamic variable
    return !this.options.context.myArray.includes(value)  
  }
);

// Note the use of passing a { context: ... } as the second "options" parameter to validateSync()
ret = schema.validateSync('yellow', { context: { myArray: ['blue', 'green'] } } );
console.assert(ret === 'yellow');  // passes validation

    let errorMessage;
try {
  schema.validateSync('blue', { context: { myArray: ['blue', 'green'] } } );
}
catch(error) {
  errorMessage = error.message;
}
console.assert(errorMessage === 'cannot be an existing value');

如何在静态yup模式中使用动态变量？

2 个答案: