@cbs-consulting/cds-eslint

ESLint plugin for CDS (Core Data Services) files with custom linting rules for better code quality and consistency.

Installation

npm install --save-dev @cbs-consulting/cds-eslint eslint

Usage

Configuration (ESLint 9+ Flat Config)

Create an eslint.config.js in your project root:

const cdsLint = require("@cbs-consulting/cds-eslint");

module.exports = [
  // Simply use the recommended config - it includes parser and all settings
  cdsLint.configs.recommended,
  
  // ...your other configs
];

That's it! The plugin handles the CDS parser internally.

Custom Configuration

If you want to customize the rules:

const cdsLint = require("@cbs-consulting/cds-eslint");

module.exports = [
  {
    files: ["**/*.cds"],
    languageOptions: {
      parser: cdsLint.parsers.cds,
    },
    plugins: {
      "@cbs-consulting/cds-eslint": cdsLint,
    },
    rules: {
      "@cbs-consulting/cds-eslint/group-by-matches-keys": "warn", // or "error"
    },
  },
];

VS Code Integration

For the best development experience with inline error highlighting in VS Code:

1. Install the ESLint extension:

   • Open VS Code
   • Go to Extensions (Ctrl+Shift+X / Cmd+Shift+X)
   • Search for "ESLint" by Microsoft
   • Click Install

2. Configure VS Code settings:

   Add to your .vscode/settings.json:

   {
     "eslint.validate": [
       "javascript",
       "javascriptreact",
       "typescript",
       "typescriptreact",
       "cds"
     ],
     "eslint.probe": [
       "javascript",
       "javascriptreact",
       "typescript",
       "typescriptreact",
       "cds"
     ],
     "eslint.options": {
       "extensions": [".js", ".jsx", ".ts", ".tsx", ".cds"]
     }
   }

3. Restart VS Code to ensure the settings take effect.

Now, CDS files will show inline errors and warnings directly in the editor!

Command Line Usage

You can also run the linter from the command line:

npx eslint "**/*.cds"

Or add to your package.json scripts:

{
  "scripts": {
    "lint": "eslint \"**/*.cds\"",
    "lint:fix": "eslint \"**/*.cds\" --fix"
  }
}

Rules

group-by-matches-keys

Ensures that GROUP BY clauses in CDS views match key columns exactly.

Rule Details:

This rule enforces that GROUP BY clauses properly align with the key columns defined in CDS entity projections and views.

Examples of incorrect code:

// ❌ Missing key in GROUP BY
entity BadExample1 as
  select from Orders as o {
    key o.ID,
    key o.OrderNo,  // ❌ OrderNo is a key but not in GROUP BY
        sum(o.price) as totalPrice
  }
  group by o.ID;

// ❌ Non-key column in GROUP BY
entity BadExample2 as
  select from Orders as o {
    key o.ID,
        o.quantity,  // ❌ quantity is not a key but is in GROUP BY
        sum(o.price) as totalPrice
  }
  group by
    o.ID,
    o.quantity;

// ❌ Undefined column in GROUP BY
entity BadExample3 as
  select from Orders as o {
    key o.productID,
        count(*) as orderCount
  }
  group by
    o.productID,
    o.customerID;  // ❌ customerID is not selected

Examples of correct code:

// ✅ All keys in GROUP BY, no non-keys
entity GoodExample1 as
  select from Orders as o {
    key o.ID,
    key o.OrderNo,
        sum(o.price) as totalPrice
  }
  group by
    o.ID,
    o.OrderNo;

// ✅ Single key with aggregation
entity GoodExample2 as
  select from Orders as o {
    key o.productID,
        count(*) as orderCount,
        sum(o.price) as totalRevenue
  }
  group by o.productID;