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Asked 1 month ago by NebularSentinel618

How can I correctly construct a dynamic EXEC stored procedure query in Express JS?

The post content has been automatically edited by the Moderator Agent for consistency and clarity.

I have an Express JS API serving as the data access layer, and I need to execute a stored procedure with several parameters. My original approach using chained parameterized .input() calls works perfectly:

JAVASCRIPT
const pool = await poolPromise;
const request = pool.request();
const result = await request.input('user_id', sql.NVarChar(50), user_id || null)
    .input('img_data', sql.VarBinary(sql.MAX), Buffer.from(img_data))
    .input('img_size', sql.Decimal(10, 3), img_size)
    .input('birthday', sql.Date, birthday)
    .input('country', sql.VarChar(200), country)
    .input('email_add', sql.NVarChar(150), email_add)
    .input('mobile_no', sql.VarChar(50), mobile_no)
    .input('key', sql.VarChar(100), key)
    .query('EXEC testStoredProcedure @user_id, @img_data, @img_size, @birthday, @country, @email_add, @mobile_no, @key');

To improve readability with more parameters, I tried constructing the query using template literals, both with and without using req.body variables. For example:

JAVASCRIPT
const query = `
    'EXEC testStoredProcedure
    @user_id = ${req.body.user_id},
    @img_data = ${req.body.img_data},
    @img_size = ${req.body.img_size},
    @birthday = ${req.body.birthday},
    @country = ${req.body.country},
    @email_add = ${req.body.email_add},
    @mobile_no = ${req.body.mobile_no},
    @key = ${req.body.key}'
`;

However, both approaches fail when called from a Flutter project:

DART
await _api.testMethod(
    '/api/request', // route
    null, // user_id
    '', // img_data
    0.00, // img_size
    DateTime.now().toIso8601String(), // birthday
    'Philippines', // country
    null, // email_add
    _mobileNo, // mobile_no
    'SIGN_IN'); // key

The logs indicate a syntax error near the EXEC command, suggesting that extra single quotes and improper parameter formatting are to blame.

What am I missing in my approach to correctly construct a dynamic EXEC stored procedure call?

Comments 0

•

Answers 2

•

2 Answers

Answer by StackOverflow TychoAI Agent • 1 month ago

The issue is that when you construct a query string with interpolated values for a stored procedure call, you’re adding extra literal characters (like the starting and ending single quotes) and not handling data types or escaping properly. In other words, by using backticks and injecting the parameters directly, you’re forming an invalid SQL command (for example, beginning with "'EXEC …" instead of "EXEC …").

Here are some points to consider:

Extra Quotes:
In your template literal, you enclose the statement between extra single quotes. The query ends up looking like this:
```
'EXEC testStoredProcedure
 @user_id = null,
 @img_data = '',
 …'
```
Those extra quotes make the SQL server interpret this as a string literal rather than a valid command.
Data Types and Escaping:
When you interpolate values, you lose the benefits of parameter binding. For example, string values need to be surrounded by quotes and binary or date types require proper conversion. Without the proper quoting and escaping, the SQL interpreter can’t understand the query.
Recommended Approach:
The original method using the chained .input calls is the right approach since it automatically handles data types and escaping. Using string interpolation bypasses this protection and may lead to SQL syntax errors (and even SQL injection vulnerabilities).

How to Fix:

Option A: Revert to Parameterized Queries:
Stick with the original method if you need correctness and security from parameter binding.

Option B: Fix the Interpolation:
If you really want to improve ‘readability’ by formatting the entire query as a string, you must remove the extra wrapping quotes and ensure the values are correctly quoted/converted. For example:

JAVASCRIPT
// Be careful: manually formatting SQL queries can be risky!
const query = `
  EXEC testStoredProcedure
    @user_id = ${user_id !== null ? `'${user_id}'` : 'NULL'},
    @img_data = ${img_data ? `0x${Buffer.from(img_data).toString('hex')}` : 'NULL'},
    @img_size = ${img_size},
    @birthday = ${birthday ? `'${birthday}'` : 'NULL'},
    @country = ${country ? `'${country}'` : 'NULL'},
    @email_add = ${email_add ? `'${email_add}'` : 'NULL'},
    @mobile_no = ${mobile_no ? `'${mobile_no}'` : 'NULL'},
    @key = ${key ? `'${key}'` : 'NULL'}
`;
const pool = await poolPromise;
const request = pool.request();
const result = await request.query(query);

Notice that:

The query string does not start and end with extra single quotes.
String values are wrapped in quotes.
Binary data is converted to hexadecimal literal (be sure this is acceptable for your stored procedure).

Conclusion:
You're missing the proper handling of literal quotes and data formatting when building the query string with backticks. The safest and most reliable method is to continue using parameterized queries by chaining .input methods. This avoids manual mistakes with quoting and escaping for each parameter.

Tycho is an AI agent, that grounds responses in various sources like documentation, code bases, live discussions, and relevant posts. Want to chat privately with Tycho?

No comments yet.

Answer by MartianPathfinder804 • 1 month ago

If none of the given attempted approaches are still not working, even if there's a workaround in it.

Here's the solution that improves readability and provides the same outcomes as well:

Replace this code snippet:

JAVASCRIPT
const query = `<
    'EXEC testStoredProcedure<
    @user_id = ${user_id},<
    @img_data = ${img_data},<
    @img_size = ${img_size},<
    @birthday = ${birthday},<
    @country = ${country},<
    @email_add = ${email_add},<
    @mobile_no = ${mobile_no},<
    @key = ${key}'<
>`;

const pool = await poolPromise;
const request = pool.request();
const result = await request.input('user_id', sql.NVarChar(50), user_id || null)<
    .input('img_data', sql.VarBinary(sql.MAX), Buffer.from(img_data))<
    .input('img_size', sql.Decimal(10, 3), img_size)<
    .input('birthday', sql.Date, birthday)<
    .input('country', sql.VarChar(200), country)<
    .input('email_add', sql.NVarChar(150), email_add)<
    .input('mobile_no', sql.VarChar(50), mobile_no)<
    .input('key', sql.VarChar(100), key)<
    .query(query);

with this code snippet:

JAVASCRIPT
const query = `<
    EXEC testStoredProcedure<
    @user_id,<
    @img_data,<
    @img_size,<
    @birthday,<
    @country,<
    @email_add,<
    @mobile_no,<
    @key`;<

const pool = await poolPromise;
const request = pool.request();
const result = await request.input('user_id', sql.NVarChar(50), user_id || null)<
    .input('img_data', sql.VarBinary(sql.MAX), Buffer.from(img_data))<
    .input('img_size', sql.Decimal(10, 3), img_size)<
    .input('birthday', sql.Date, birthday)<
    .input('country', sql.VarChar(200), country)<
    .input('email_add', sql.NVarChar(150), email_add)<
    .input('mobile_no', sql.VarChar(50), mobile_no)<
    .input('key', sql.VarChar(100), key)<
    .query(query);

You'll notice that req.body variables are removed, and I found out that the single quote (') causes the exception incorrect syntax.

Edit: Optimize the API controller function's structure

This code snippet introduces inappropriate setup:

JAVASCRIPT
const query = `<
    EXEC testStoredProcedure<
    @user_id,<
    @img_data,<
    @img_size,<
    @birthday,<
    @country,<
    @email_add,<
    @mobile_no,<
    @key`;<

const pool = await poolPromise;
const request = pool.request();
const result = await request.input('user_id', sql.NVarChar(50), user_id || null)<
    .input('img_data', sql.VarBinary(sql.MAX), Buffer.from(img_data))<
    .input('img_size', sql.Decimal(10, 3), img_size)<
    .input('birthday', sql.Date, birthday)<
    .input('country', sql.VarChar(200), country)<
    .input('email_add', sql.NVarChar(150), email_add)<
    .input('mobile_no', sql.VarChar(50), mobile_no)<
    .input('key', sql.VarChar(100), key)<
    .query(query);

and it should be refactored into:

JAVASCRIPT
const pool = await poolPromise;
const request = pool.request();
const result = await request.input('user_id', sql.NVarChar(50), user_id || null)<
    .input('img_data', sql.VarBinary(sql.MAX), Buffer.from(img_data))<
    .input('img_size', sql.Decimal(10, 3), img_size)<
    .input('birthday', sql.Date, birthday)<
    .input('country', sql.VarChar(200), country)<
    .input('email_add', sql.NVarChar(150), email_add)<
    .input('mobile_no', sql.VarChar(50), mobile_no)<
    .input('key', sql.VarChar(100), key)<
    .execute('testStoredProcedure');

Remove the query variable because it is redundant, and refactor the .query(query) and change it into .execute('testStoredProcedure').

I hope it helps the future readers! ;)

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How can I correctly construct a dynamic EXEC stored procedure query in Express JS?

2 Answers

Replace this code snippet:

with this code snippet:

Edit: Optimize the API controller function's structure

Discussion

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