Description

In CDS 10 the consistent_params compat flag is removed and its behavior — req.params is always an array of objects — becomes the permanent, non-configurable default. Previously, projects that had not yet opted in via cds.features.consistent_params: true could still receive req.params entries as primitives for single-key entities. Any code that treats req.params[i] as a primitive (a plain string or number) will now receive an object instead, causing unexpected behaviour or runtime errors. Code that already accesses req.params[i].KeyField is unaffected.

How to Check

• [ ] Search for cds.features.consistent_params in package.json, .cdsrc.json, and environment-specific config files — remove it regardless of value.
• [ ] Run the pattern_ast patterns to find all req.params[i] accesses and const [x] = req.params destructuring.
• [ ] For each match, verify whether the element is subsequently used as a primitive (e.g. passed to ===, used in a template literal without .KeyField, or inserted directly into a query).
• [ ] Check test assertions that compare req.params[0] to a scalar value.

Migration Steps

1. Remove the consistent_params flag from CDS configuration:

   // package.json or .cdsrc.json
     "cds": {
       "features": {
   -     "consistent_params": true
       }
     }

2. Update code that treats req.params entries as primitives to access the key field explicitly:

   - const id = req.params[0]; // was a primitive string/number
   + const { ID } = req.params[0]; // always an object now
     const book = await db.read(Books, id);

3. Update array-destructuring patterns:

   - const [id] = req.params;
   + const [{ ID: id }] = req.params;

4. Update test assertions that compare params entries to scalar values:

   - expect(req.params[0]).toBe('42');
   + expect(req.params[0]).toEqual({ ID: '42' });