feat: do not require koa as dependency (#13)

This lets you publish libraries that validate koa requests, but don't depend on koa.

package.json

@@ -16,6 +16,7 @@
     "test": "jest --no-cache",
     "test:coverage": "yarn test --coverage",
     "test:watch": "yarn test --watch",
+    "posttest": "tsc --noEmit",
     "clean": "rimraf lib && rimraf src/Example.validator.ts",
     "prebuild": "yarn clean",
     "build": "tsc",
@@ -68,7 +69,7 @@
     "json-stable-stringify": "^1.0.1",
     "minimatch": "^3.0.4",
     "tsconfig": "^7.0.0",
-    "typescript-json-schema": "^0.38.0",
+    "typescript-json-schema": "^0.38.3",
     "yargs": "^13.2.4"
   }
 }

src/__tests__/output/ComplexExample.usage.ts

@@ -0,0 +1,5 @@
+import {Context} from 'koa';
+import {validateKoaRequest, RequestA} from './ComplexExample.validator';
+
+declare const x: Context;
+export const y: RequestA = validateKoaRequest('RequestA')(x);

src/__tests__/output/ComplexExample.valiator.ts → src/__tests__/output/ComplexExample.validator.ts

@@ -1,7 +1,12 @@
 import Ajv = require('ajv');
-import {Context} from 'koa';
-import {inspect} from 'util';
 import {MyEnum, TypeA, TypeB, RequestA, RequestB} from '../../ComplexExample';
+import {inspect} from 'util';
+export interface KoaContext {
+  readonly request?: unknown; // {body?: unknown}
+  readonly params?: unknown;
+  readonly query?: unknown;
+  throw(status: 400, message: string): unknown;
+}
 export const ajv = new Ajv({allErrors: true, coerceTypes: false});
 
 ajv.addMetaSchema(require('ajv/lib/refs/json-schema-draft-06.json'));
@@ -75,7 +80,7 @@ ajv.addSchema(Schema, 'Schema');
 export function validateKoaRequest(
   typeName: 'RequestA',
 ): (
-  ctx: Context,
+  ctx: KoaContext,
 ) => {
   params: RequestA['params'];
   query: RequestA['query'];
@@ -84,7 +89,7 @@ export function validateKoaRequest(
 export function validateKoaRequest(
   typeName: 'RequestB',
 ): (
-  ctx: Context,
+  ctx: KoaContext,
 ) => {
   params: unknown;
   query: RequestB['query'];
@@ -93,7 +98,7 @@ export function validateKoaRequest(
 export function validateKoaRequest(
   typeName: string,
 ): (
-  ctx: Context,
+  ctx: KoaContext,
 ) => {
   params: unknown;
   query: unknown;
@@ -102,7 +107,7 @@ export function validateKoaRequest(
 export function validateKoaRequest(
   typeName: string,
 ): (
-  ctx: Context,
+  ctx: KoaContext,
 ) => {
   params: any;
   query: any;
@@ -118,7 +123,7 @@ export function validateKoaRequest(
   const validateProperty = (
     prop: string,
     validator: any,
-    ctx: Context,
+    ctx: KoaContext,
   ): any => {
     const data =
       prop === 'body'
@@ -133,7 +138,11 @@ export function validateKoaRequest(
           'Invalid request: ' +
             ajv.errorsText(validator.errors, {dataVar: prop}) +
             '\n\n' +
-            inspect({params: ctx.params, query: ctx.query, body: ctx.body}),
+            inspect({
+              params: ctx.params,
+              query: ctx.query,
+              body: ctx.request && (ctx.request as any).body,
+            }),
         );
       }
     }

src/__tests__/printValidator.test.ts

@@ -3,18 +3,29 @@ import {printTypeCollectionValidator} from '../printValidator';
 import {writeFileSync} from 'fs';
 import prettierFile from '../prettierFile';
 
-let validate: typeof import('./output/ComplexExample.valiator') = undefined as any;
+let validate: typeof import('./output/ComplexExample.validator') = undefined as any;
 
 test('print', () => {
   const {symbols, schema} = parse([
     __dirname + '/../ComplexExample.ts',
   ]).getAllTypes();
   writeFileSync(
-    __dirname + '/output/ComplexExample.valiator.ts',
+    __dirname + '/output/ComplexExample.validator.ts',
     printTypeCollectionValidator(symbols, schema, '../../ComplexExample'),
   );
-  prettierFile(__dirname + '/output/ComplexExample.valiator.ts');
-  validate = require('./output/ComplexExample.valiator');
+  prettierFile(__dirname + '/output/ComplexExample.validator.ts');
+  writeFileSync(
+    __dirname + '/output/ComplexExample.usage.ts',
+    `
+  import {Context} from 'koa';
+  import {validateKoaRequest, RequestA} from './ComplexExample.validator';
+  
+  declare const x: Context;
+  export const y: RequestA = validateKoaRequest('RequestA')(x);
+  `,
+  );
+  prettierFile(__dirname + '/output/ComplexExample.usage.ts');
+  validate = require('./output/ComplexExample.validator');
 });
 test('validateValue', () => {
   expect(validate.validate('MyEnum')(0)).toBe(0);

src/printValidator.ts

@@ -24,8 +24,8 @@ export function printTypeCollectionValidator(
   });
   return [
     t.IMPORT_AJV,
-    ...(koaTypes.length ? [t.IMPORT_KOA_CONTEXT, t.IMPORT_INSPECT] : []),
     t.importNamedTypes(symbols, relativePath),
+    ...(koaTypes.length ? [t.IMPORT_INSPECT, t.DECLARE_KOA_CONTEXT] : []),
     t.declareAJV(options),
     t.exportNamed(symbols),
     t.declareSchema('Schema', schema),

src/template.ts

@@ -6,7 +6,13 @@ export type GENERATED_COMMENT = `// generated by typescript-json-validator`;
 
 export const IMPORT_INSPECT = `import {inspect} from 'util';`;
 export const IMPORT_AJV = `import Ajv = require('ajv');`;
-export const IMPORT_KOA_CONTEXT = `import {Context} from 'koa';`;
+
+export const DECLARE_KOA_CONTEXT = `export interface KoaContext {
+  readonly request?: unknown; // {body?: unknown}
+  readonly params?: unknown;
+  readonly query?: unknown;
+  throw(status: 400, message: string): unknown;
+}`;
 
 export const importNamedTypes = (names: string[], relativePath: string) =>
   `import {${names.join(', ')}} from '${relativePath}';`;
@@ -78,19 +84,19 @@ export const validateKoaRequestOverload = (
   typeName: string,
   schema: TJS.Definition,
 ) =>
-  `export function validateKoaRequest(typeName: '${typeName}'): (ctx: Context) => {
+  `export function validateKoaRequest(typeName: '${typeName}'): (ctx: KoaContext) => {
   params: ${typeOf(typeName, 'params', schema)},
   query: ${typeOf(typeName, 'query', schema)},
   body: ${typeOf(typeName, 'body', schema)},
 };`;
 
-export const VALIDATE_KOA_REQUEST_FALLBACK = `export function validateKoaRequest(typeName: string): (ctx: Context) => {
+export const VALIDATE_KOA_REQUEST_FALLBACK = `export function validateKoaRequest(typeName: string): (ctx: KoaContext) => {
   params: unknown,
   query: unknown,
   body: unknown,
 };`;
 
-export const VALIDATE_KOA_REQUEST_IMPLEMENTATION = `export function validateKoaRequest(typeName: string): (ctx: Context) => {
+export const VALIDATE_KOA_REQUEST_IMPLEMENTATION = `export function validateKoaRequest(typeName: string): (ctx: KoaContext) => {
   params: any,
   query: any,
   body: any,
@@ -101,7 +107,7 @@ export const VALIDATE_KOA_REQUEST_IMPLEMENTATION = `export function validateKoaR
   const validateProperty = (
     prop: string,
     validator: any,
-    ctx: Context,
+    ctx: KoaContext,
   ): any => {
     const data = prop === 'body' ? ctx.request && (ctx.request as any).body : (ctx as any)[prop];
     if (validator) {
@@ -110,7 +116,7 @@ export const VALIDATE_KOA_REQUEST_IMPLEMENTATION = `export function validateKoaR
       if (!valid) {
         ctx.throw(
           400,
-          'Invalid request: ' + ajv.errorsText(validator.errors, {dataVar: prop}) + '\\n\\n' + inspect({params: ctx.params, query: ctx.query, body: ctx.body}),
+          'Invalid request: ' + ajv.errorsText(validator.errors, {dataVar: prop}) + '\\n\\n' + inspect({params: ctx.params, query: ctx.query, body: ctx.request && (ctx.request as any).body}),
         );
       }
     }