Improve performance for const schemas

benchmark/bench.js

@@ -213,6 +213,60 @@ const benchmarks = [
       n5: 42,
       b5: true
     }
+  },
+  {
+    name: 'object with const string property',
+    schema: {
+      type: 'object',
+      properties: {
+        a: { const: 'const string' }
+      }
+    },
+    input: { a: 'const string' }
+  },
+  {
+    name: 'object with const number property',
+    schema: {
+      type: 'object',
+      properties: {
+        a: { const: 1 }
+      }
+    },
+    input: { a: 1 }
+  },
+  {
+    name: 'object with const bool property',
+    schema: {
+      type: 'object',
+      properties: {
+        a: { const: true }
+      }
+    },
+    input: { a: true }
+  },
+  {
+    name: 'object with const object property',
+    schema: {
+      type: 'object',
+      properties: {
+        foo: { const: { bar: 'baz' } }
+      }
+    },
+    input: {
+      foo: { bar: 'baz' }
+    }
+  },
+  {
+    name: 'object with const null property',
+    schema: {
+      type: 'object',
+      properties: {
+        foo: { const: null }
+      }
+    },
+    input: {
+      foo: null
+    }
   }
 ]
 

index.js

@@ -361,6 +361,7 @@ function buildCode (location) {
     code += buildValue(propertyLocation, `obj[${JSON.stringify(key)}]`)
 
     const defaultValue = schema.properties[key].default
+
     if (defaultValue !== undefined) {
       code += `
       } else {
@@ -796,7 +797,7 @@ function buildValue (location, input) {
   }
 
   let type = schema.type
-  const nullable = schema.nullable === true
+  const nullable = schema.nullable === true || (Array.isArray(type) && type.includes('null'))
 
   let code = ''
   let funcName
@@ -805,6 +806,17 @@ function buildValue (location, input) {
     type = 'string'
   }
 
+  if ('const' in schema) {
+    if (nullable) {
+      code += `
+        json += ${input} === null ? 'null' : '${JSON.stringify(schema.const)}'
+      `
+      return code
+    }
+    code += `json += '${JSON.stringify(schema.const)}'`
+    return code
+  }
+
   switch (type) {
     case 'null':
       code += 'json += serializer.asNull()'
@@ -865,13 +877,6 @@ function buildValue (location, input) {
         code += `
           json += JSON.stringify(${input})
         `
-      } else if ('const' in schema) {
-        code += `
-          if(ajv.validate(${JSON.stringify(schema)}, ${input}))
-            json += '${JSON.stringify(schema.const)}'
-          else
-            throw new Error(\`Item $\{JSON.stringify(${input})} does not match schema definition.\`)
-        `
       } else if (schema.type === undefined) {
         code += `
           json += JSON.stringify(${input})

test/const.test.js

@@ -24,6 +24,184 @@ test('schema with const string', (t) => {
   t.ok(validate(JSON.parse(output)), 'valid schema')
 })
 
+test('schema with const string and different input', (t) => {
+  t.plan(2)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      foo: { const: 'bar' }
+    }
+  }
+
+  const validate = validator(schema)
+  const stringify = build(schema)
+  const output = stringify({
+    foo: 'baz'
+  })
+
+  t.equal(output, '{"foo":"bar"}')
+  t.ok(validate(JSON.parse(output)), 'valid schema')
+})
+
+test('schema with const string and different type input', (t) => {
+  t.plan(2)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      foo: { const: 'bar' }
+    }
+  }
+
+  const validate = validator(schema)
+  const stringify = build(schema)
+  const output = stringify({
+    foo: 1
+  })
+
+  t.equal(output, '{"foo":"bar"}')
+  t.ok(validate(JSON.parse(output)), 'valid schema')
+})
+
+test('schema with const string and no input', (t) => {
+  t.plan(2)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      foo: { const: 'bar' }
+    }
+  }
+
+  const validate = validator(schema)
+  const stringify = build(schema)
+  const output = stringify({})
+
+  t.equal(output, '{}')
+  t.ok(validate(JSON.parse(output)), 'valid schema')
+})
+
+test('schema with const number', (t) => {
+  t.plan(2)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      foo: { const: 1 }
+    }
+  }
+
+  const validate = validator(schema)
+  const stringify = build(schema)
+  const output = stringify({
+    foo: 1
+  })
+
+  t.equal(output, '{"foo":1}')
+  t.ok(validate(JSON.parse(output)), 'valid schema')
+})
+
+test('schema with const number and different input', (t) => {
+  t.plan(2)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      foo: { const: 1 }
+    }
+  }
+
+  const validate = validator(schema)
+  const stringify = build(schema)
+  const output = stringify({
+    foo: 2
+  })
+
+  t.equal(output, '{"foo":1}')
+  t.ok(validate(JSON.parse(output)), 'valid schema')
+})
+
+test('schema with const bool', (t) => {
+  t.plan(2)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      foo: { const: true }
+    }
+  }
+
+  const validate = validator(schema)
+  const stringify = build(schema)
+  const output = stringify({
+    foo: true
+  })
+
+  t.equal(output, '{"foo":true}')
+  t.ok(validate(JSON.parse(output)), 'valid schema')
+})
+
+test('schema with const number', (t) => {
+  t.plan(2)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      foo: { const: 1 }
+    }
+  }
+
+  const validate = validator(schema)
+  const stringify = build(schema)
+  const output = stringify({
+    foo: 1
+  })
+
+  t.equal(output, '{"foo":1}')
+  t.ok(validate(JSON.parse(output)), 'valid schema')
+})
+
+test('schema with const null', (t) => {
+  t.plan(2)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      foo: { const: null }
+    }
+  }
+
+  const validate = validator(schema)
+  const stringify = build(schema)
+  const output = stringify({
+    foo: null
+  })
+
+  t.equal(output, '{"foo":null}')
+  t.ok(validate(JSON.parse(output)), 'valid schema')
+})
+
+test('schema with const array', (t) => {
+  t.plan(2)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      foo: { const: [1, 2, 3] }
+    }
+  }
+
+  const validate = validator(schema)
+  const stringify = build(schema)
+  const output = stringify({
+    foo: [1, 2, 3]
+  })
+
+  t.equal(output, '{"foo":[1,2,3]}')
+  t.ok(validate(JSON.parse(output)), 'valid schema')
+})
+
 test('schema with const object', (t) => {
   t.plan(2)
 
@@ -44,6 +222,56 @@ test('schema with const object', (t) => {
   t.ok(validate(JSON.parse(output)), 'valid schema')
 })
 
+test('schema with const and null as type', (t) => {
+  t.plan(4)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      foo: { type: ['string', 'null'], const: 'baz' }
+    }
+  }
+
+  const validate = validator(schema)
+  const stringify = build(schema)
+  const output = stringify({
+    foo: null
+  })
+
+  t.equal(output, '{"foo":null}')
+  t.ok(validate(JSON.parse(output)), 'valid schema')
+
+  const output2 = stringify({ foo: 'baz' })
+  t.equal(output2, '{"foo":"baz"}')
+  t.ok(validate(JSON.parse(output2)), 'valid schema')
+})
+
+test('schema with const as nullable', (t) => {
+  t.plan(4)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      foo: { nullable: true, const: 'baz' }
+    }
+  }
+
+  const validate = validator(schema)
+  const stringify = build(schema)
+  const output = stringify({
+    foo: null
+  })
+
+  t.equal(output, '{"foo":null}')
+  t.ok(validate(JSON.parse(output)), 'valid schema')
+
+  const output2 = stringify({
+    foo: 'baz'
+  })
+  t.equal(output2, '{"foo":"baz"}')
+  t.ok(validate(JSON.parse(output2)), 'valid schema')
+})
+
 test('schema with const and invalid object', (t) => {
   t.plan(2)
 
@@ -55,13 +283,12 @@ test('schema with const and invalid object', (t) => {
     required: ['foo']
   }
 
+  const validate = validator(schema)
   const stringify = build(schema)
-  try {
-    stringify({
-      foo: { foo: 'baz' }
-    })
-  } catch (err) {
-    t.match(err.message, /^Item .* does not match schema definition/, 'Given object has invalid const value')
-    t.ok(err)
-  }
+  const result = stringify({
+    foo: { foo: 'baz' }
+  })
+
+  t.equal(result, '{"foo":{"foo":"bar"}}')
+  t.ok(validate(JSON.parse(result)), 'valid schema')
 })