Template strings and INSERT statements

• Deno Version: 1.7.4
• Deno-Postgres Version: 0.8.0
• Database: CockroachDB

I’m trying to run an INSERT statement using a Pooled connection and template strings. The following is the query being ran:

const result = await client.queryObject(
  `INSERT INTO acme.warehouses (warehouse_id, warehouse_name) VALUES (default, ${'charleston'})`,
  name,
);

Where ${'charleston'} comes from a variable and throws the following:

error: Uncaught (in promise) PostgresError: column "charleston" does not exist
    return new PostgresError(parseWarning(msg));
         ^
    at parseError (warning.ts:34:10)
    at Connection.processError (connection.ts:613:19)
    at Connection._simpleQuery (connection.ts:476:20)
    at async Connection.query (connection.ts:712:16)
    at async mod.ts:99:20

The following two queries do, however, work:

const result = await client.queryObject(
  "INSERT INTO acme.warehouses (warehouse_id, warehouse_name) VALUES (default, 'charleston')"
);

const result = await client.queryObject(
  "INSERT INTO acme.warehouses (warehouse_id, warehouse_name) VALUES (default, $1)",
  "charleston",
);

I’ve created and referenced the connection as recommended by the docs.

[Soremwar]

Hi there @realStandal

I understand your confusion, however this is pretty simple to explain. You are mixing up two different concepts when executing a query: Template strings and function parameters

In the cases you described above, the following is executed by the driver:

const result = await client.queryObject(
  "INSERT INTO acme.warehouses (warehouse_id, warehouse_name) VALUES (default, 'charleston')"
);
// Plain statement executed as is

const result = await client.queryObject(
  "INSERT INTO acme.warehouses (warehouse_id, warehouse_name) VALUES (default, $1)",
  "charleston", // Query parameters
);
// Prepared statement, on execution time your database will understand that the value $1 maps to, is "charleston" in this case

const result = await client.queryObject(
  `INSERT INTO acme.warehouses (warehouse_id, warehouse_name) VALUES (default, ${'charleston'})`,
  name,
);

This is actually a plain statement, cause you are not using query parameters or template strings, causing your query to be passed to PostgreSQL as the following

INSERT INTO acme.warehouses (warehouse_id, warehouse_name) VALUES (default, charleston)

And since charleston is not surrounded by single quotes and doesn’t map to any query parameter, it’s though to be a database column rather than a literal value

In order to execute a query the way you intend it, means rewriting it into the following:

// Using template strings
const result = await client.queryObject`INSERT INTO acme.warehouses (warehouse_id, warehouse_name) VALUES (default, ${'charleston'})`;

// Using plain text
const result = await client.queryObject(
  // Notice the extra quotes surrounding "charleston"
  `INSERT INTO acme.warehouses (warehouse_id, warehouse_name) VALUES (default, '${'charleston'}')`,
);

[tv42]

I just got stumped by this too.

Could I suggest changing the documentation at https://deno-postgres.com/#/?id=prepared-statement-with-template-strings to emphasize that it’s a tagged string literal, and not just backquotes.

I think the way the example code is displayed is absolutely hurting, making the tagged string harder to recognize. Could I recommend rewriting

  const result = await client.queryObject
    `SELECT ID, NAME FROM PEOPLE WHERE AGE > ${min} AND AGE < ${max}`;

as

  const result = await client.queryObject`
    SELECT ID, NAME FROM PEOPLE WHERE AGE > ${min} AND AGE < ${max}
  `;