feat: dynRef for dynamic member referencing

Author: paveltiunov

packages/cubejs-schema-compiler/compiler/CubeSymbols.js

@@ -1,5 +1,6 @@
 const R = require('ramda');
 const UserError = require('./UserError');
+const DynamicReference = require('./DynamicReference');
 
 const FunctionRegex = /function\s+\w+\(([A-Za-z0-9_,]*)|\(([\s\S]*?)\)\s+|\(?(\w+)\)?\s+=>\s/;
 const CONTEXT_SYMBOLS = {
@@ -92,7 +93,11 @@ class CubeSymbols {
     const oldContext = this.resolveSymbolsCallContext;
     this.resolveSymbolsCallContext = context;
     try {
-      return func.apply(null, this.funcArguments(func).map((id) => nameResolver(id.trim())));
+      let res = func.apply(null, this.funcArguments(func).map((id) => nameResolver(id.trim())));
+      if (res instanceof DynamicReference) {
+        res = res.fn.apply(null, res.memberNames.map((id) => nameResolver(id.trim())));
+      }
+      return res;
     } finally {
       this.resolveSymbolsCallContext = oldContext;
     }

packages/cubejs-schema-compiler/compiler/DynamicReference.js

@@ -0,0 +1,8 @@
+class DynamicReference {
+  constructor(memberNames, fn) {
+    this.memberNames = memberNames;
+    this.fn = fn;
+  }
+}
+
+module.exports = DynamicReference;

packages/cubejs-schema-compiler/compiler/PrepareCompiler.js

@@ -10,6 +10,7 @@ const DashboardTemplateEvaluator = require('./DashboardTemplateEvaluator');
 const JoinGraph = require('./JoinGraph');
 const Funnels = require('../extensions/Funnels');
 const RefreshKeys = require('../extensions/RefreshKeys');
+const Reflection = require('../extensions/Reflection');
 const CubeToMetaTransformer = require('./CubeToMetaTransformer');
 
 exports.compile = (repo, options) => {
@@ -38,7 +39,8 @@ exports.prepareCompiler = (repo, options) => {
     cubeFactory: cubeSymbols.createCube.bind(cubeSymbols),
     extensions: {
       Funnels,
-      RefreshKeys
+      RefreshKeys,
+      Reflection
     }
   }, options));
   return {

packages/cubejs-schema-compiler/extensions/Reflection.js

@@ -0,0 +1,24 @@
+const R = require('ramda');
+const DynamicReference = require('../compiler/DynamicReference');
+
+class RefreshKeys {
+  constructor(cubeFactory, compiler) {
+    this.cubeFactory = cubeFactory;
+    this.compiler = compiler;
+    this.dynRef = this.dynRef.bind(this);
+  }
+
+  dynRef(...args) {
+    if (args.length < 2) {
+      throw new Error(`List of references and a function are expected in form: dynRef('ref', (r) => (...))`);
+    }
+    const references = R.dropLast(1, args);
+    const fn = args[args.length - 1];
+    if (typeof fn !== 'function') {
+      throw new Error(`Last argument should be a function`);
+    }
+    return new DynamicReference(references, fn);
+  }
+}
+
+module.exports = RefreshKeys;

packages/cubejs-schema-compiler/test/ExtensionsTest.js

@@ -1,13 +1,17 @@
-const CompileError = require('../compiler/CompileError');
+/* globals it,describe */
+/* eslint-disable quote-props */
 const PostgresQuery = require('../adapter/PostgresQuery');
 const PrepareCompiler = require('./PrepareCompiler');
 require('should');
 
-const prepareCompiler = PrepareCompiler.prepareCompiler;
+const { prepareCompiler } = PrepareCompiler;
 
 describe('Extensions', () => {
-  const { compiler, joinGraph, cubeEvaluator, transformer } = prepareCompiler(`
+  const {
+    compiler, joinGraph, cubeEvaluator
+  } = prepareCompiler(`
     const Funnels = require('Funnels');
+    import { dynRef } from 'Reflection';
 
     cube(\`VisitorsFunnel\`, {
       extends: Funnels.eventFunnel({
@@ -49,7 +53,14 @@ describe('Extensions', () => {
     })
 
     cube(\`FooBar\`, {
-      extends: VisitorsFunnel
+      extends: VisitorsFunnel,
+      
+      measures: {
+        conversionsFraction: {
+          sql: dynRef('conversions', (c) => \`\${c} / 100.0\`),
+          type: 'number'
+        }
+      }
     })
     `);
 
@@ -72,4 +83,24 @@ describe('Extensions', () => {
 
     return result;
   });
+
+  it('dyn ref', () => {
+    const result = compiler.compile().then(() => {
+      const query = new PostgresQuery({ joinGraph, cubeEvaluator, compiler }, {
+        measures: [
+          'FooBar.conversionsFraction'
+        ],
+        timeDimensions: [{
+          dimension: 'FooBar.time',
+          granularity: 'day',
+          dateRange: { from: '2017-01-01', to: '2017-01-30' }
+        }],
+        timezone: 'America/Los_Angeles'
+      });
+
+      console.log(query.buildSqlAndParams()[0]);
+    });
+
+    return result;
+  });
 });