This is a Prisma Error Map, it provides clear error messages for common issues like duplicate records, missing data, or constraint violations.

errorMap.prisma.ts

import {
  BadRequestException,
  NotFoundException,
  ConflictException,
  InternalServerErrorException,
} from '@nestjs/common';

export enum PrismaErrorCode {
  P2000 = 'P2000',
  P2001 = 'P2001',
  P2002 = 'P2002',
  P2003 = 'P2003',
  P2006 = 'P2006',
  P2007 = 'P2007',
  P2008 = 'P2008',
  P2009 = 'P2009',
  P2010 = 'P2010',
  P2011 = 'P2011',
  P2012 = 'P2012',
  P2014 = 'P2014',
  P2015 = 'P2015',
  P2016 = 'P2016',
  P2017 = 'P2017',
  P2018 = 'P2018',
  P2019 = 'P2019',
  P2021 = 'P2021',
  P2025 = 'P2025',
  P2031 = 'P2031',
  P2033 = 'P2033',
  P2034 = 'P2034',
  P2037 = 'P2037',
  P1000 = 'P1000',
  P1001 = 'P1001',
  P1002 = 'P1002',
  P1015 = 'P1015',
  P1017 = 'P1017',
}

interface PrismaErrorMeta {
  target?: string;
  model?: string;
  relationName?: string;
  details?: string;
}

export type operationT = 'create' | 'read' | 'update' | 'delete';

export type PrismaErrorHandler = (
  operation: operationT,
  meta?: PrismaErrorMeta,
) => Error;

export const ERROR_MAP: Record<PrismaErrorCode, PrismaErrorHandler> = {
  P2000: (_operation, meta) =>
    new BadRequestException(
      `The provided value for ${meta?.target || 'a field'} is too long. Please use a shorter value.`,
    ),

  P2001: (operation, meta) =>
    new NotFoundException(
      `The ${meta?.model || 'record'} you are trying to ${operation} could not be found.`,
    ),

  P2002: (operation, meta) => {
    const field = meta?.target || 'unique field';
    switch (operation) {
      case 'create':
        return new ConflictException(
          `A record with the same ${field} already exists. Please use a different value.`,
        );
      case 'update':
        return new ConflictException(
          `The new value for ${field} conflicts with an existing record.`,
        );
      default:
        return new ConflictException(
          `Unique constraint violation on ${field}.`,
        );
    }
  },

  P2003: (operation) =>
    new BadRequestException(
      `Foreign key constraint failed. Unable to ${operation} the record because related data is invalid or missing.`,
    ),

  P2006: (_operation, meta) =>
    new BadRequestException(
      `The provided value for ${meta?.target || 'a field'} is invalid. Please correct it.`,
    ),

  P2007: (operation) =>
    new InternalServerErrorException(
      `Data validation error during ${operation}. Please ensure all inputs are valid and try again.`,
    ),

  P2008: (operation) =>
    new InternalServerErrorException(
      `Failed to query the database during ${operation}. Please try again later.`,
    ),

  P2009: (operation) =>
    new InternalServerErrorException(
      `Invalid data fetched during ${operation}. Check query structure.`,
    ),

  P2010: () =>
    new InternalServerErrorException(
      `Invalid raw query. Ensure your query is correct and try again.`,
    ),

  P2011: (_operation, meta) =>
    new BadRequestException(
      `The required field ${meta?.target || 'a field'} is missing. Please provide it to continue.`,
    ),

  P2012: (operation, meta) =>
    new BadRequestException(
      `Missing required relation ${meta?.relationName || ''}. Ensure all related data exists before ${operation}.`,
    ),

  P2014: (operation) => {
    switch (operation) {
      case 'create':
        return new BadRequestException(
          `Cannot create record because the referenced data does not exist. Ensure related data exists.`,
        );
      case 'delete':
        return new BadRequestException(
          `Unable to delete record because it is linked to other data. Update or delete dependent records first.`,
        );
      default:
        return new BadRequestException(`Foreign key constraint error.`);
    }
  },

  P2015: () =>
    new InternalServerErrorException(
      `A record with the required ID was expected but not found. Please retry.`,
    ),

  P2016: (operation) =>
    new InternalServerErrorException(
      `Query ${operation} failed because the record could not be fetched. Ensure the query is correct.`,
    ),

  P2017: (operation) =>
    new InternalServerErrorException(
      `Connected records were not found for ${operation}. Check related data.`,
    ),

  P2018: () =>
    new InternalServerErrorException(
      `The required connection could not be established. Please check relationships.`,
    ),

  P2019: (_operation, meta) =>
    new InternalServerErrorException(
      `Invalid input for ${meta?.details || 'a field'}. Please ensure data conforms to expectations.`,
    ),

  P2021: (_operation, meta) =>
    new InternalServerErrorException(
      `The ${meta?.model || 'model'} was not found in the database.`,
    ),

  P2025: (operation, meta) =>
    new NotFoundException(
      `The ${meta?.model || 'record'} you are trying to ${operation} does not exist. It may have been deleted.`,
    ),

  P2031: () =>
    new InternalServerErrorException(
      `Invalid Prisma Client initialization error. Please check configuration.`,
    ),

  P2033: (operation) =>
    new InternalServerErrorException(
      `Insufficient database write permissions for ${operation}.`,
    ),

  P2034: (operation) =>
    new InternalServerErrorException(
      `Database read-only transaction failed during ${operation}.`,
    ),

  P2037: (operation) =>
    new InternalServerErrorException(
      `Unsupported combinations of input types for ${operation}. Please correct the query or input.`,
    ),

  P1000: () =>
    new InternalServerErrorException(
      `Database authentication failed. Verify your credentials and try again.`,
    ),

  P1001: () =>
    new InternalServerErrorException(
      `The database server could not be reached. Please check its availability.`,
    ),

  P1002: () =>
    new InternalServerErrorException(
      `Connection to the database timed out. Verify network connectivity and server availability.`,
    ),

  P1015: (operation) =>
    new InternalServerErrorException(
      `Migration failed. Unable to complete ${operation}. Check migration history or database state.`,
    ),

  P1017: () =>
    new InternalServerErrorException(
      `Database connection failed. Ensure the database is online and credentials are correct.`,
    ),
};