Joi 验证器条件模式

Question

I need to create dynamic schema to validate my api request query in node js using Joi validator depending on a key in the request query. Say the following below mentioned pattern are my valid queries.

I'm using hapi/joi version 16.1.8

Combination 1

{ type: 1, firstname: 'user first name', lastname: 'user last name'}

Combination 2

{ type: 2 , salary: 1000, pension: 200}

Combination 3

{ type: 3 , credit: 550, debit: 100}

As you can see the object keys varies depending on the value of type . How this can be handled properly?

We can handle two conditions using Joi.alternatives like

const schema = Joi.alternatives().conditional(Joi.object({ type: 1 }).unknown(), {
    then: Joi.object({
        type: Joi.string(),
        firstname: Joi.string(),
        lastname: Joi.string()
    }),
    otherwise: Joi.object({
        type: Joi.number(),
        salary: Joi.any(),
        pension: Joi.any()
    })
});

But how this can be done for 3 conditions?

Answer 1

I achieved the same in a little different manner. Posting the same here since this might be useful for someone in future.

const schema = Joi.object({
    type: Joi.number().required().valid(1, 2, 3),
    firstname: Joi.alternatives().conditional('type', { is: 1, then: Joi.string().required() }),
    lastname: Joi.alternatives().conditional('type', { is: 1, then: Joi.string().required() }),
    salary: Joi.alternatives().conditional('type', { is: 2, then: Joi.number().required() }),
    pension: Joi.alternatives().conditional('type', { is: 2, then: Joi.number().required() }),
    credit: Joi.alternatives().conditional('type', { is: 3, then: Joi.number().required() }),
    debit: Joi.alternatives().conditional('type', { is: 3, then: Joi.number().required() }),
}))

This was working perfectly as expected.

When the type value is 1 the object should have only type , firstname and lastname

When the type value is 2 the object should have only type , salary and pension

When the type value is 3 the object should have only type , credit and debit

Any other combination will be thrown as error from the joi validator middleware layer. Also any other type value other that 1, 2 and 3 will be throwing error.

Answer 2

It works for me!

var Joi = require('joi');

var schema = {
    a: Joi.any().when('b', { is: 5, then: Joi.required(), otherwise: Joi.optional() }),
    b: Joi.any()
};

var thing = {
    b: 5
};
var validate = Joi.validate(thing, schema);

// returns
{
    error: null,
    value: {
        b: 5
    }
}

This is the reference .

Answer 3

In the documentation it look like switch is valid key to use along alternatives.conditional . Could you try the following ?

const schema = Joi.alternatives().conditional(Joi.object({
  type: 1
}).unknown(), {
  switch: [{
    is: 1,

    then: Joi.object({
      type: Joi.string(),
      firstname: Joi.string(),
      lastname: Joi.string(),
    }),
  }, {
    is: 2,

    then: Joi.object({
      type: Joi.number(),
      salary: Joi.any(),
      pension: Joi.any(),
    }),
  }, {
    // ...
  }],
});

---

EDIT :

Couldn't find any example anywhere about the use of the switch keyword...

But found some other way to achieve it in hapijs/joi github

const schema = Joi.object({
     a: Joi.number().required(),
     b: Joi.alternatives()
             .conditional('a', [
                 { is: 0, then: Joi.valid(1) },
                 { is: 1, then: Joi.valid(2) },
                 { is: 2, then: Joi.valid(3), otherwise: Joi.valid(4) }
    ])
});

Answer 4

I was trying to find a way to do something similar. Then I was able to figure it out.

const Joi = require('joi');
const schema = Joi.object({
  type: Joi.number().valid(1,2,3),
  // anything common
}).when(Joi.object({type: Joi.number().valid(1)}).unknown(), {
  then: Joi.object({
    firstname: Joi.string(),
    lastname: Joi.string(),
  })
})
.when(Joi.object({type: Joi.number().valid(2)}).unknown(), {
  then: Joi.object({
    salary: Joi.number(),
    pension: Joi.number(),
  })
})
.when(Joi.object({type: Joi.number().valid(3)}).unknown(), {
  then: Joi.object({
    credit: Joi.number(),
    debit: Joi.number(),
  })
});

Answer 5

I was looking to do the same but instead of query param the condition should depend on the request method. I ended up with the next solution:

const schema = Joi.when(Joi.ref("$requestMethod"), {
  switch: [
    {
      is: "POST",
      then: Joi.object({
        name: Joi.string().trim().max(150).required(),
        description: Joi.string().max(255),
        active: Joi.boolean().required(),
        }),
      }),
    },
    {
      is: "PUT",
      then: Joi.object({
        name: Joi.string().trim().max(150).required(),
        description: Joi.string().max(255),            
      }),
    },
  ],
});


schema.validate(req.body, { context: { requestMethod: req.method } });

Joi when() condition documentation https://joi.dev/api/?v=17.4.1#anywhencondition-options

Answer 6

Using the conditional/switch, of which syntax is also more readable.

The following Joi excerpt will enforce the presence of $.referenceClass when $.type === Type.REFERENCE . When it does, it will ensure that values are the accepted ones - ...classIds .

Otherwise ( $.type !== Type.REFERENCE ), it won't allow the presence of $.referenceClass (except you run the validation with the option of allowing extra keys).

{
    type: Joi.string().valid( ...Hub.types ).required(),
    referenceClass: Joi.alternatives().conditional( 'type', {
        switch: [
            { is: Type.REFERENCE, then: Joi.string().valid( ...classIds ) },
        ],
    } ),
}