# TypeScript codegen: PascalCase table keys in tablesSchema cause 'columns' undefined crash on subscription

[Reperion]

Love SpaceTimeDB, congrats on your launch of 2.0, and that video was EPIC :D

Since I am a n00b coder, I ran into an issue and had an a.i. summarise;

Bug Summary

The TypeScript code generator (spacetime generate --lang typescript) produces PascalCase keys in the client tablesSchema object (e.g., Report, ReportCategory), but the SpacetimeDB wire protocol sends table names using the actual snake_case name field values (e.g., report, report_category). The SDK looks up tables by sourceName which is set to the PascalCase key, causing a crash when processing subscription messages.

Error

Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'columns')
    at DbConnection.parseRowList_fn (spacetimedb.js:6484:46)
    at DbConnection.queryRowsToTableUpdates_fn (spacetimedb.js:6532:87)
    at DbConnection.processMessage_fn (spacetimedb.js:6653:107)

Version

• SpacetimeDB CLI: 2.0.1 (commit a4d29daec8ed35ce4913a335b7210b9ae3933d00)
• spacetimedb npm package: 2.0.1
• Module language: TypeScript
• Client framework: React (via spacetimedb/react)

Root Cause

In the SDK source at src/lib/schema.ts:94, tableToSchema() sets sourceName: accName where accName is the object key from the generated tablesSchema:

// schema.ts line 93-95
return {
  sourceName: accName,   // ← set to the PascalCase key
  accessorName: accName,
  ...
};

In src/sdk/db_connection_impl.ts:207-216, the #sourceNameToTableDef map is keyed by table.sourceName:

this.#sourceNameToTableDef[table.sourceName] = table;

When processing subscription messages at line 427, the SDK looks up the table using the wire table name (snake_case from the server):

const table = this.#sourceNameToTableDef[tableName];  // tableName = "report" from wire
const columnsArray = Object.entries(table.columns);    // table is undefined → crash

The mismatch: the map has key "Report" (PascalCase from codegen) but the wire sends "report" (snake_case from DB).

Reproduction

1. Create a TypeScript module with a table:

import { schema, table, t } from 'spacetimedb/server';

const User = table(
  { name: 'user', public: true },
  { identity: t.identity().primaryKey(), username: t.string().optional() }
);

const spacetimedb = schema({ User });
export default spacetimedb;

2. Publish and generate bindings:

spacetime publish mydb --no-config -s local
spacetime generate --lang typescript --out-dir ./src/module_bindings --module-path ./spacetimedb

3. The generated src/module_bindings/index.ts contains:

const tablesSchema = __schema({
  User: __table({ name: 'user', ... }, UserRow),  // ← PascalCase key "User"
});

4. Connect from a client and subscribe:

conn.subscriptionBuilder().subscribe(['SELECT * FROM user']);

5. Crash — the server sends table name "user" but the SDK only has "User" in its lookup map.

Workaround

Manually edit the generated index.ts to use snake_case keys matching the name field:

const tablesSchema = __schema({
  user: __table({ name: 'user', ... }, UserRow),           // was: User
  report_category: __table({ name: 'report_category', ... }, ReportCategoryRow),  // was: ReportCategory
});

Then update all client references from tables.User to tables.user, etc.

Suggested Fix

The codegen should use the table's name field value as the key in tablesSchema, not the PascalCase-converted name. Alternatively, tableToSchema() could read the name from the table definition and use that as sourceName instead of accName.

Environment

• macOS 25.3.0 (Apple Silicon)
• Node.js v25.4.0
• Bun v1.3.8

[mandipadk]

Yup, same problem

[0monish]

Same here

[Shubham8287]

We will release the fix today itself.

[Reperion]

Where is this world going, a n00b (me) writing bug reports after noticing my a.i. struggling, where on V1 it had no issue.. which turns out to be valid input.
And then it gets fixed. SpaceTimeDB FTW.