Creating MySQL queries programmatically using data stored in a JSON object

Question

Creating MySQL queries programmatically using data stored in a JSON object

Is it possible to construct a MySQL query dynamically from a JSON object with potentially empty values?

For instance, starting with an object like this:

{
  "a": 1
  "b": ""
  "c": "foo"
}

we want to generate a query like the following (ignoring the empty value for "b") :

SELECT * FROM db.table
WHERE a = 1
AND c = "foo"

or

SELECT * FROM db.table
WHERE a = 1
AND b = ????
AND c = "foo"

Edit : It may be a duplicate question. However, I was hoping for a more SQL-oriented approach, possibly involving variables and IF statements.

Edit 2 : I have discovered a method (working in node.js API but should work similarly in other languages) :

const jsonObj = {
"a": 1,
"b": "",
"c": "foo"
}

const query = `
SELECT * FROM db.table
WHERE
IF('${jsonObj.a}' != '', a = '${jsonObj.a}', 1=1)
AND 
IF('${jsonObj.b}' != '', b = '${jsonObj.b}', 1=1)
AND 
IF('${jsonObj.c}' != '', c = '${jsonObj.c}', 1=1)
`

Please note that this code is not ready for use as-is; adjustments are needed to address potential injection vulnerabilities.

javascript mysql json

Answer 1

Answer №1

Please Note: It is important to be aware that this strategy is susceptible to SQL Injection Attacks. To prevent this, it is crucial to escape the values properly, preferably by utilizing prepared queries. Without sufficient understanding of your database client, providing specific guidance on how to do this is challenging.

Additionally: I highly recommend implementing a whitelist for allowed columns and only allowing column keys within the whitelist to be utilized in your query. Below, you will find an example incorporating a whitelist to illustrate this concept.

Below is an MVP designed to handle a dynamic object and construct a SQL statement based on your specifications:

const obj = {
  "a": 1,
  "b": "",
  "c": "foo",
  "bad": "disallowed"
}

// Example of how to use a whitelist
const whitelist = ['a', 'c'];

// Initialize an empty array to store the WHERE conditions
let where = [];

// Iterate through each key / value in the object
Object.keys(obj).forEach(function (key) {
    // If the key is not whitelisted, do not proceed
    if ( ! whitelist.includes(key) ) {
        return;
    }

    // Do not proceed if the value is an empty string
    if ( '' === obj[key] ) {
        return;
    }

    // Add the clause to the array of conditions if all conditions are met
    where.push(`\`${key}\` = "${obj[key]}"`);
});

// Convert the array of conditions into a string of AND clauses
where = where.join(' AND ');

// Prepend the WHERE keyword if there is a WHERE string
if (where) {
    where = `WHERE ${where}`;
}

const sql = `SELECT * FROM table ${where}`;

console.log(sql);
// SELECT * FROM table WHERE `a` = "1" AND `c` = "foo"

NOTES:

It is important to mention that providing any form of character escaping goes beyond the scope of this question / answer. This method may fail if values include double-quote characters (e.g., ")
Moreover, offering a solution to determine if the value is numeric and refrain from enclosing it in quotes in the query exceeds the bounds of this question / answer. Nonetheless, many databases can handle a numeric value enclosed in quotes successfully.

Answer 2

Please Note: It is important to be aware that this strategy is susceptible to SQL Injection Attacks. To prevent this, it is crucial to escape the values properly, preferably by utilizing prepared queries. Without sufficient understanding of your database client, providing specific guidance on how to do this is challenging.

Additionally: I highly recommend implementing a whitelist for allowed columns and only allowing column keys within the whitelist to be utilized in your query. Below, you will find an example incorporating a whitelist to illustrate this concept.

Below is an MVP designed to handle a dynamic object and construct a SQL statement based on your specifications:

const obj = {
  "a": 1,
  "b": "",
  "c": "foo",
  "bad": "disallowed"
}

// Example of how to use a whitelist
const whitelist = ['a', 'c'];

// Initialize an empty array to store the WHERE conditions
let where = [];

// Iterate through each key / value in the object
Object.keys(obj).forEach(function (key) {
    // If the key is not whitelisted, do not proceed
    if ( ! whitelist.includes(key) ) {
        return;
    }

    // Do not proceed if the value is an empty string
    if ( '' === obj[key] ) {
        return;
    }

    // Add the clause to the array of conditions if all conditions are met
    where.push(`\`${key}\` = "${obj[key]}"`);
});

// Convert the array of conditions into a string of AND clauses
where = where.join(' AND ');

// Prepend the WHERE keyword if there is a WHERE string
if (where) {
    where = `WHERE ${where}`;
}

const sql = `SELECT * FROM table ${where}`;

console.log(sql);
// SELECT * FROM table WHERE `a` = "1" AND `c` = "foo"

NOTES:

It is important to mention that providing any form of character escaping goes beyond the scope of this question / answer. This method may fail if values include double-quote characters (e.g., ")
Moreover, offering a solution to determine if the value is numeric and refrain from enclosing it in quotes in the query exceeds the bounds of this question / answer. Nonetheless, many databases can handle a numeric value enclosed in quotes successfully.

Answer 3

Answer №2

Discover the power of a versatile function designed to handle complex queries

function createQueryParams(params) {
    const constraints = [];
    const data = [];
    Object.keys(params).forEach((item) => {
        if (!params[item] || params[item] == "") {
            return;
        }
        if (Array.isArray(params[item])) {
            constraints.push(`${item} in (?)`);
            data.push(params[item]);
        } else if (typeof params[item] === "string" && params[item].indexOf(",") > -1) {
            constraints.push(`${item} in (?)`);
            data.push(params[item].split(","));
        } else if (params[item] instanceof RegExp) {
            constraints.push(`${item} REGEXP ?`);
            data.push(params[item]);
        } else if (params[item] && typeof params[item] === "object") {
            Object.keys(params[item]).forEach((value) => {
                if (value === "$gte") {
                    constraints.push(`${item} >= ?`);
                    data.push(params[item][value]);
                } else if (value === "$lte") {
                    constraints.push(`${item} <= ?`);
                    data.push(params[item][value]);
                } else if (value === "$gt") {
                    constraints.push(`${item} > ?`);
                    data.push(params[item][value]);
                } else if (value === "$lt") {
                    constraints.push(`${item} < ?`);
                    data.push(params[item][value]);
                } else if (value === "$like") {
                    if (Array.isArray(params[item][value])) {
                        const localConstraints = [];
                        params[item][value].forEach((likeValues) => {
                            localConstraints.push(`${item} LIKE ?`);
                            data.push(`%${likeValues}%`);
                        });
                        constraints.push(`(${localConstraints.join(" OR ")})`);
                    } else if (typeof params[item][value] === "string" && params[item][value].indexOf(",") > -1) {
                        const localConstraints = [];
                        params[item][value] = params[item][value].split(",");
                        params[item][value].forEach((likeValues) => {
                            localConstraints.push(`${item} LIKE ?`);
                            data.push(`%${likeValues}%`);
                        });
                        constraints.push(`(${localConstraints.join(" OR ")})`);
                    } else {
                        constraints.push(`${item} LIKE ?`);
                        data.push(`%${params[item][value]}%`);
                    }
                }
            });
        } else {
            constraints.push(`${item} = ?`);
            data.push(params[item]);
        }
    });
    return { constraints, data };
}

const input = {
    userId: 1,
    company: ["google", "microsoft"],
    username: { $like: "Test" },
    name: { $like: [ "Test1", "Test2" ] },
    age: { $gt: 10 }
}
const queryData = createQueryParams(input);
console.log("SELECT * FROM user WHERE ", queryData.constraints.join(" and "));
console.log(queryData.data);

This multifunctional tool provides a structured approach to escape characters in queries effectively. By using this method, you can safeguard against SQL injection attacks. It is recommended for users utilizing the mysql package

Answer 4

Discover the power of a versatile function designed to handle complex queries

function createQueryParams(params) {
    const constraints = [];
    const data = [];
    Object.keys(params).forEach((item) => {
        if (!params[item] || params[item] == "") {
            return;
        }
        if (Array.isArray(params[item])) {
            constraints.push(`${item} in (?)`);
            data.push(params[item]);
        } else if (typeof params[item] === "string" && params[item].indexOf(",") > -1) {
            constraints.push(`${item} in (?)`);
            data.push(params[item].split(","));
        } else if (params[item] instanceof RegExp) {
            constraints.push(`${item} REGEXP ?`);
            data.push(params[item]);
        } else if (params[item] && typeof params[item] === "object") {
            Object.keys(params[item]).forEach((value) => {
                if (value === "$gte") {
                    constraints.push(`${item} >= ?`);
                    data.push(params[item][value]);
                } else if (value === "$lte") {
                    constraints.push(`${item} <= ?`);
                    data.push(params[item][value]);
                } else if (value === "$gt") {
                    constraints.push(`${item} > ?`);
                    data.push(params[item][value]);
                } else if (value === "$lt") {
                    constraints.push(`${item} < ?`);
                    data.push(params[item][value]);
                } else if (value === "$like") {
                    if (Array.isArray(params[item][value])) {
                        const localConstraints = [];
                        params[item][value].forEach((likeValues) => {
                            localConstraints.push(`${item} LIKE ?`);
                            data.push(`%${likeValues}%`);
                        });
                        constraints.push(`(${localConstraints.join(" OR ")})`);
                    } else if (typeof params[item][value] === "string" && params[item][value].indexOf(",") > -1) {
                        const localConstraints = [];
                        params[item][value] = params[item][value].split(",");
                        params[item][value].forEach((likeValues) => {
                            localConstraints.push(`${item} LIKE ?`);
                            data.push(`%${likeValues}%`);
                        });
                        constraints.push(`(${localConstraints.join(" OR ")})`);
                    } else {
                        constraints.push(`${item} LIKE ?`);
                        data.push(`%${params[item][value]}%`);
                    }
                }
            });
        } else {
            constraints.push(`${item} = ?`);
            data.push(params[item]);
        }
    });
    return { constraints, data };
}

const input = {
    userId: 1,
    company: ["google", "microsoft"],
    username: { $like: "Test" },
    name: { $like: [ "Test1", "Test2" ] },
    age: { $gt: 10 }
}
const queryData = createQueryParams(input);
console.log("SELECT * FROM user WHERE ", queryData.constraints.join(" and "));
console.log(queryData.data);

This multifunctional tool provides a structured approach to escape characters in queries effectively. By using this method, you can safeguard against SQL injection attacks. It is recommended for users utilizing the mysql package

Creating MySQL queries programmatically using data stored in a JSON object

Answer №1

Answer №2

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