Allow empty schemas as properties. (#105)

It allows covering opaque types.

I am using this together with a GraphQL endpoint which has custom scalars. These scalars are opaque from the type system so a JSON schema cannot be derived.

Author: ruiaraujo

index.js

@@ -726,7 +726,13 @@ function nested (laterCode, name, key, schema, externalSchema, fullSchema, subKe
         code += `
           else json+= null
         `
-      } else throw new Error(`${schema} unsupported`)
+      } else if (isEmpty(schema)) {
+        code += `
+          json += JSON.stringify(obj${accessor})
+        `
+      } else {
+        throw new Error(`${schema} unsupported`)
+      }
       break
     default:
       if (Array.isArray(type)) {
@@ -814,4 +820,11 @@ function isValidSchema (schema, externalSchema) {
   ajv.removeSchema()
 }
 
+function isEmpty (schema) {
+  for (var key in schema) {
+    if (schema.hasOwnProperty(key)) return false
+  }
+  return true
+}
+
 module.exports = build

test/any.test.js

@@ -0,0 +1,79 @@
+'use strict'
+
+const test = require('tap').test
+const build = require('..')
+
+test('object with nested random property', (t) => {
+  t.plan(4)
+
+  const schema = {
+    title: 'empty schema to allow any object',
+    type: 'object',
+    properties: {
+      id: {
+        type: 'number'
+      },
+      name: {}
+    }
+  }
+  const stringify = build(schema)
+
+  try {
+    const value = stringify({
+      id: 1,
+      name: 'string'
+    })
+    t.is(value, '{"id":1,"name":"string"}')
+  } catch (e) {
+    t.fail()
+  }
+  try {
+    const value = stringify({
+      id: 1,
+      name: {
+        first: 'name',
+        last: 'last'
+      }
+    })
+    t.is(value, '{"id":1,"name":{"first":"name","last":"last"}}')
+  } catch (e) {
+    t.fail()
+  }
+  try {
+    const value = stringify({
+      id: 1,
+      name: null
+    })
+    t.is(value, '{"id":1,"name":null}')
+  } catch (e) {
+    t.fail()
+  }
+  try {
+    const value = stringify({
+      id: 1,
+      name: ['first', 'last']
+    })
+    t.is(value, '{"id":1,"name":["first","last"]}')
+  } catch (e) {
+    t.fail()
+  }
+})
+
+test('array with random items', (t) => {
+  t.plan(1)
+
+  const schema = {
+    title: 'empty schema to allow any object',
+    type: 'array',
+    items: {
+    }
+  }
+  const stringify = build(schema)
+
+  try {
+    const value = stringify([1, 'string', null])
+    t.is(value, '[1,"string",null]')
+  } catch (e) {
+    t.fail()
+  }
+})