feat: add RegExpAsString GraphQL custom scalar type for filtration by RegExp

Author: nodkz

src/types/RegExpAsString.ts

@@ -0,0 +1,40 @@
+import { GraphQLScalarType, Kind } from 'graphql-compose/lib/graphql';
+
+function parseStringWithRegExp(str: string): RegExp {
+  if (str.startsWith('/')) {
+    const m = str.match(/^\/(.+)\/([gimsuy]*)$/);
+    if (m) {
+      return new RegExp(m[1], m[2]);
+    }
+    throw new TypeError('Field error: cannot parse provided string as RegExp object');
+  } else {
+    // simple regexp without expression flags
+    return new RegExp(str);
+  }
+}
+
+const GraphQLRegExpAsString = new GraphQLScalarType({
+  name: 'RegExpAsString',
+  specifiedByUrl: 'http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-262.pdf',
+  description:
+    'The string representation of JavaScript regexp. You may provide it with flags "/^abc.*/i" or without flags like "^abc.*". More info about RegExp characters and flags: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions',
+  serialize: String,
+  parseValue(value: any) {
+    if (typeof value !== 'string') {
+      throw new TypeError(
+        'Field error: GraphQL RegExpAsString value should be provided as a string'
+      );
+    }
+    return parseStringWithRegExp(value);
+  },
+  parseLiteral(ast) {
+    if (ast.kind !== Kind.STRING) {
+      throw new TypeError(
+        'Field error: GraphQL RegExpAsString value should be provided as a string'
+      );
+    }
+    return parseStringWithRegExp(ast.value);
+  },
+});
+
+export default GraphQLRegExpAsString;

src/types/__tests__/RegExpAsString-test.ts

@@ -0,0 +1,60 @@
+import { Kind } from 'graphql-compose/lib/graphql';
+import GraphQLRegExpAsString from '../RegExpAsString';
+
+describe('GraphQLRegExpAsString', () => {
+  describe('serialize', () => {
+    it('pass RegExp without flags', () => {
+      expect(GraphQLRegExpAsString.serialize(new RegExp('^Abc$'))).toBe('/^Abc$/');
+      expect(GraphQLRegExpAsString.serialize(new RegExp(/^Abc$/))).toBe('/^Abc$/');
+    });
+
+    it('pass RegExp with flags', () => {
+      expect(GraphQLRegExpAsString.serialize(new RegExp('^Abc$', 'gm'))).toBe('/^Abc$/gm');
+    });
+
+    it('pass as String', () => {
+      expect(GraphQLRegExpAsString.serialize('abc')).toBe('abc');
+    });
+  });
+
+  describe('parseValue', () => {
+    it('pass as string', () => {
+      expect(GraphQLRegExpAsString.parseValue('^Abc$')).toEqual(/^Abc$/);
+      expect(GraphQLRegExpAsString.parseValue('/^Abc$/')).toEqual(/^Abc$/);
+      expect(GraphQLRegExpAsString.parseValue('/^Abc$/gm')).toEqual(/^Abc$/gm);
+      expect(GraphQLRegExpAsString.parseValue('so/me')).toEqual(/so\/me/);
+    });
+
+    it('pass as wrong type', () => {
+      expect(() => GraphQLRegExpAsString.parseValue(123)).toThrow(
+        'value should be provided as a string'
+      );
+    });
+  });
+
+  describe('parseLiteral', () => {
+    it('parse a ast STRING literal', async () => {
+      const ast = {
+        kind: Kind.STRING,
+        value: '^Abc$',
+      };
+      expect(GraphQLRegExpAsString.parseLiteral(ast, {})).toEqual(/^Abc$/);
+
+      const ast2 = {
+        kind: Kind.STRING,
+        value: '/^Abc$/gm',
+      };
+      expect(GraphQLRegExpAsString.parseLiteral(ast2, {})).toEqual(/^Abc$/gm);
+    });
+
+    it('parse wrong ast literal', async () => {
+      const ast: any = {
+        kind: Kind.INT,
+        value: 123,
+      };
+      expect(() => GraphQLRegExpAsString.parseLiteral(ast, {})).toThrow(
+        'value should be provided as a string'
+      );
+    });
+  });
+});