[Fixed] Prisma: TypeError: Do not know how to serialize a BigInt – Prisma

BigInt.prototype.toJSON = function () {
  const int = Number.parseInt(this.toString());
  return int ?? this.toString();
};

The Problem:

"When fetching data from a database using Prisma, a TypeError is encountered when encountering a specific character (?", specifically ‘?’, in the data. The error message is ‘TypeError: Do not know how to serialize a?’ and is related to JSON serialization. The data in question is a model property with a name that contains the character ‘?’, such as ‘uniq_users?". The goal is to find a way to handle this character during data serialization to prevent the error and successfully fetch the data."
}

The Solutions:

Solution 1: Avoid `JSON.stringify`

To avoid encountering this error, prevent your entity id from being included in a JSON.stringify function. For example, if Prisma returns the following data:

const user = prisma.user.create({ data: { id: 1, name: "user"} })

JSON.stringify(user) will raise an error if the user id is of type BigInt.

To resolve this, convert the BigInt id to a string before stringifying the data:

JSON.stringify({...user, id: user.id.toString()})

Solution 3: **Custom function**

This solution involves creating a custom function to convert BigInt values to strings before serializing them to JSON. Here’s how it works:

1. Create a helper function:

   Create a function that takes a value as a parameter and converts all BigInts in that value to strings. For example:

   const bigIntToString = (param) => {
     return JSON.stringify(
       param,
       (key, value) => (typeof value === "bigint" ? value.toString() : value) // return everything else unchanged
     );
   };
   

2. Use the custom function:

   When you need to serialize data from Prisma to JSON, use the custom function you created. For instance:

   const users = await prisma.user.findMany({
     take: 15,
   });
   res.status(200).type('json').send(bigIntToString(users));
   

This custom function ensures that BigInt values are properly converted to strings before serialization, resolving the error you encountered.

Solution

\n
” and the solution provided as:

Video Explanation:

The following video, titled "”How", provides additional insights and in-depth exploration related to the topics discussed in this post.

”…

OPTION … UNHANDLED RUNTIME ERROR TYPEERROR: DO NOT KNOW HOW TO SERIALIZE A BIGINT …”]