console.log cannot be used as a default

[bruceferguson2]

What version of Ajv are you using? Does the issue happen if you use the latest version?

8.16.0

Ajv options object

{allErrors: true, useDefaults: true}

JSON Schema

{
  type: "object",
  properties: {
    report: {default: console.log}
  }
}

Sample data

Your code

import Ajv from "ajv";

const ajv = new Ajv({allErrors: true, useDefaults: true});

ajv.addKeyword({
  valid: true,
  keyword: "report",
});

const schema = {
  type: "object",
  properties: {
    report: {default: console.log}
  }
}

const validator = ajv.compile(schema);

Validation result, data AFTER validation, error messages

/home/me/apps/dbtest/node_modules/ajv/dist/compile/codegen/code.js:135
        .replace(/\u2028/g, "\\u2028")
        ^

TypeError: Cannot read properties of undefined (reading 'replace')
    at safeStringify (/home/ubuntu/apps/dbtest/node_modules/ajv/dist/compile/codegen/code.js:135:9)
    at stringify (/home/ubuntu/apps/dbtest/node_modules/ajv/dist/compile/codegen/code.js:130:22)
    at assignDefault (/home/ubuntu/apps/dbtest/node_modules/ajv/dist/compile/validate/defaults.js:33:82)
    at assignDefaults (/home/ubuntu/apps/dbtest/node_modules/ajv/dist/compile/validate/defaults.js:10:13)
    at iterateKeywords (/home/ubuntu/apps/dbtest/node_modules/ajv/dist/compile/validate/index.js:218:39)
    at groupKeywords (/home/ubuntu/apps/dbtest/node_modules/ajv/dist/compile/validate/index.js:200:13)
    at /home/ubuntu/apps/dbtest/node_modules/ajv/dist/compile/validate/index.js:192:13
    at CodeGen.code (/home/ubuntu/apps/dbtest/node_modules/ajv/dist/compile/codegen/index.js:439:13)
    at CodeGen.block (/home/ubuntu/apps/dbtest/node_modules/ajv/dist/compile/codegen/index.js:568:18)
    at schemaKeywords (/home/ubuntu/apps/dbtest/node_modules/ajv/dist/compile/validate/index.js:190:9)

Node.js v20.10.0

What results did you expect?

That "console.log" would be used as the default value.

Are you going to resolve the issue?

[jasoniangreen]

JSON Schema can only deal with data that can ultimately be serialised as a JSON string. Functions cannot be represented in JSON so you won't be able to use a function like log as a default, nor as a value within JSON. For example, try JSON.stringify({func: console.log}) and you'll see it doesn't work.