const ajv = new Ajv({ processCode: transpileFunc });
const validate = ajv.compile(schema); // transpiled es7 async function
validate(data).then(successFunc).catch(errorFunc);

const ajv = new Ajv()

ajv.addKeyword({
  keyword: "idExists"
  async: true,
  type: "number",
  validate: checkIdExists,
})

async function checkIdExists(schema, data) {
  // this is just an example, you would want to avoid SQL injection in your code
  const rows = await sql(`SELECT id FROM ${schema.table} WHERE id = ${data}`)
  return !!rows.length // true if record is found
}

const schema = {
  $async: true,
  properties: {
    userId: {
      type: "integer",
      idExists: {table: "users"},
    },
    postId: {
      type: "integer",
      idExists: {table: "posts"},
    },
  },
}

const validate = ajv.compile(schema)

validate({userId: 1, postId: 19})
  .then(function (data) {
    console.log("Data is valid", data) // { userId: 1, postId: 19 }
  })
  .catch(function (err) {
    if (!(err instanceof Ajv.ValidationError)) throw err
    // data is invalid
    console.log("Validation errors:", err.errors)
  })

const ajv = new Ajv({ processCode: transpileFunc });
const validate = ajv.compile(schema); // transpiled es7 async function
validate(data).then(successFunc).catch(errorFunc);

const ajv = new Ajv()

ajv.addKeyword({
  keyword: "idExists"
  async: true,
  type: "number",
  validate: checkIdExists,
})

async function checkIdExists(schema, data) {
  // this is just an example, you would want to avoid SQL injection in your code
  const rows = await sql(`SELECT id FROM ${schema.table} WHERE id = ${data}`)
  return !!rows.length // true if record is found
}

const schema = {
  $async: true,
  properties: {
    userId: {
      type: "integer",
      idExists: {table: "users"},
    },
    postId: {
      type: "integer",
      idExists: {table: "posts"},
    },
  },
}

const validate = ajv.compile(schema)

validate({userId: 1, postId: 19})
  .then(function (data) {
    console.log("Data is valid", data) // { userId: 1, postId: 19 }
  })
  .catch(function (err) {
    if (!(err instanceof Ajv.ValidationError)) throw err
    // data is invalid
    console.log("Validation errors:", err.errors)
  })

const ajv = new Ajv({ loadSchema: loadSchema });

ajv.compileAsync(schema).then(function (validate) {
  const valid = validate(data);
  // ...
});

async function loadSchema(uri) {
  const res = await request.json(uri);
  if (res.statusCode >= 400)
    throw new Error("Loading error: " + res.statusCode);
  return res.body;
}

const ajv = new Ajv({ loadSchema: loadSchema });

ajv.compileAsync(schema).then(function (validate) {
  const valid = validate(data);
  // ...
});

async function loadSchema(uri) {
  const res = await request.json(uri);
  if (res.statusCode >= 400)
    throw new Error("Loading error: " + res.statusCode);
  return res.body;
}

const schema = {
  type: "object",
  required: ["foo"],
  properties: {
    foo: { type: "integer" },
  },
  additionalProperties: false,
  errorMessage: {
    type: "should be an object", // will not replace internal "type" error for the property "foo"
    required: "should have property foo",
    additionalProperties:
      "should not have properties other than foo",
  },
};

const validate = ajv.compile(schema);
console.log(validate({ foo: "a", bar: 2 })); // false
console.log(validate.errors); // processed errors

const schema = {
  type: "object",
  required: ["foo"],
  properties: {
    foo: { type: "integer" },
  },
  additionalProperties: false,
  errorMessage:
    "should be an object with an integer property foo only",
};

const validate = ajv.compile(schema);
console.log(validate({ foo: "a", bar: 2 })); // false
console.log(validate.errors); // processed errors

const schema = {
  type: "object",
  required: ["foo", "bar"],
  allOf: [
    {
      properties: {
        foo: { type: "integer", minimum: 2 },
        bar: { type: "string", minLength: 2 },
      },
      additionalProperties: false,
    },
  ],
  errorMessage: {
    properties: {
      foo: "data.foo should be integer >= 2",
      bar: "data.bar should be string with length >= 2",
    },
  },
};

const validate = ajv.compile(schema);
console.log(validate({ foo: 1, bar: "a" })); // false
console.log(validate.errors); // processed errors

const schema = {
  type: "object",
  required: ["foo", "bar"],
  allOf: [
    {
      properties: {
        foo: { type: "integer", minimum: 2 },
        bar: { type: "string", minLength: 2 },
      },
      additionalProperties: false,
    },
  ],
  errorMessage: {
    type: "data should be an object",
    properties: {
      foo: "data.foo should be integer >= 2",
      bar: "data.bar should be string with length >= 2",
    },
    _: 'data should have properties "foo" and "bar" only',
  },
};

const validate = ajv.compile(schema);
console.log(validate({})); // false
console.log(validate.errors); // processed errors