How can I check if value is object or array of objects via Joi

Question

My request body can be a single JSON object or array of JSON objects:

Single JSON Object

{
   "name" : "item 1",
   "description" : "item 1 description"
}

Array of JSON Object

[{
   "name" : "item 1",
   "description" : "item 1 description"
}, {
   "name" : "item 2",
   "description" : "item 2 description"
}
]

I want to validate these cases via celebrate/Joi

export const Create = celebrate({
    [ Segments.BODY ]: Joi.any() // how can I handle them here
});

`Joi.array()` and `Joi.object()`? You can validate the contents of the array via `Joi.array().items(Joi.object({}))` — Abana Clara, Feb 14 '20 at 07:33
Joi.array().items(Joi.object({})) while doing this when the value is single JSON object the error is thrown(an array is expected). — Arman Kostandyan, Feb 14 '20 at 11:30
`an array is expected` means you used a non-array. In order to have multiple validations on one property/variable you need to make an interable `[Joi.object(), Joi.array()]` — Abana Clara, Feb 14 '20 at 11:37
https://stackoverflow.com/questions/26509551/joi-validation-multiple-conditions — Rahul Patil, Feb 14 '20 at 11:48
@RahulPatil I checked that question, my case is different. I don't have any key/value to validate the body using them. — Arman Kostandyan, Feb 14 '20 at 11:59

terrymorse · Answer 1 · 2020-02-14T15:55:28.687

1

How to tell if item is array or object, using vanilla JavaScript:

    const arrayOrObject = (item) => {
      if (item instanceof Array) return ‘array’;
      else if (item instanceof Object) return ‘object’;
      return null;
    }

A similar "array or object" test using Joi:

    const Joi = require('@hapi/joi');

    const isArray = (item) => !Joi.array().validate(item).error;
    const isObject = (item) => !Joi.object().validate(item).error;

    let arr = [1,2,3];
    console.log(isArray(arr));  // true
    console.log(isObject(arr)); // false

    obj = {foo: "bar"};
    console.log(isArray(obj));  // false
    console.log(isObject(obj)); // true

edited Feb 14 '20 at 15:55

answered Feb 14 '20 at 08:05

terrymorse

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Thanks for your response, but I need to do it with **Joi**. – Arman Kostandyan Feb 14 '20 at 11:32
Okay, I added a very simple `Joi` method. Is that what you are seeking? If you need to do further validation, you could first do the "array-or-object" test, then choose the appropriate validator schema (object or array of objects). – terrymorse Feb 14 '20 at 16:02
thanks again, I can do it in this way, but I would prefer to do it with Celebrate(https://www.npmjs.com/package/celebrate), all my validations are handled in that way. If you can help with it I would be most grateful)) – Arman Kostandyan Feb 17 '20 at 07:25

score 1 · Answer 2 · answered Jul 23 '20 at 11:29

You can try the following -

const obj = {
   name: Joi.string(),
   description: Joi.string()
}

const joiObj = Joi.object(obj);

const joiArray = Joi.array().items(joiObj);

const joiSchema = Joi.alternatives().try(joiObj, joiArray);

const result = joiSchema.validate(payload);

if(result.error) {
  throw(result.error);
}


return payload;

You might have to work the error response (result.error) in order to get the desired error message for the API consumer but that's about it.

Let me know if this helps!

How can I check if value is object or array of objects via Joi

2 Answers2