Is There A Way To Merge Joi Schemas?

Question

Is there any way to merge two joi schemas into a single schema?

Schema 1

{
  alpha: Joi.number().required(),
  beta: Joi.string().required(),
  chalie: Joi.object({
    xray: Joi.number().required(),
  }).required()
}

Schema 1

{
  delta: Joi.string().required(),
  echo: Joi.number().required(),
  charlie: Joi.object({
    zulu: Joi.string().required(),
  }).required()
}

Merged Schema:

{
  alpha: Joi.number().required(),
  beta: Joi.string().required(),
  chalie: Joi.object({
    xray: Joi.number().required(),
    zulu: Joi.string().required(),
  }).required()
  delta: Joi.string().required(),
  echo: Joi.number().required(),
}

Without nested objects it's easily done with Object.assign, but even a deep object merge won't work with the nested objects because the nested object is a function call.

Answer 1

I was wondering the same thing, as I wanted to merge two different schemas, and found this: https://github.com/hapijs/joi/blob/v9.0.4/API.md#anyconcatschema

const a = Joi.string().valid('a');
const b = Joi.string().valid('b');
const ab = a.concat(b);

Hope that helps you

Answer 2

Did you try Joi.append?

https://github.com/hapijs/joi/blob/v13.5.2/API.md#objectkeysschema

// Validate key a
const base = Joi.object().keys({
    a: Joi.number()
});

// Validate keys a, b.
const extended = base.append({
    b: Joi.string()
});

UPDATED (2020-05-03):

An easy way to accomplish that would be like this:

var base = Joi.object({ firstname: Joi.string() });
var fullName = base.keys({ lastName: Joi.number() });

Answer 3

Using plain javascript objects was not an option for me. I tried using the .keys method to extend but it overwrites existing keys (for charlie in this case).

The solution I settled on was using .reach: Example:

const Joi = require('joi');
const originalSchema = Joi.object({
  a: { 
    deep: {
      b: Joi.string()
    }    
  },
  c: Joi.string()
});
const extendedSchema = Joi.object({
  a: { 
    deep: Joi
      .reach(originalSchema, 'a.deep')
      .keys({ anotherB: Joi.string() })
  },
  c: Joi.reach(originalSchema, 'c')
});

// No errors
extendedSchema.validate({ a: { deep: { b: 'hi', anotherB: 'hi' } }, c: 'wow' })