How to fix P2019: Input error in Prisma

try {
  const result = await prisma.user.findMany({
    where: {
      metadata: {
        path: ['preferences', 'theme'],
        // Missing the required scalar filter!
      }
    }
  });
} catch (error) {
  if (error instanceof Prisma.PrismaClientKnownRequestError) {
    if (error.code === 'P2019') {
      console.log('Input error:', error.message);
      // Example message: "Input error. A JSON path cannot be set without a scalar filter"
    }
  }
}

// ❌ WRONG - Missing scalar filter causes P2019
const users = await prisma.user.findMany({
  where: {
    metadata: {
      path: ['preferences', 'theme'],
    }
  }
});

// ✅ CORRECT - Include scalar filter
const users = await prisma.user.findMany({
  where: {
    metadata: {
      path: ['preferences', 'theme'],
      equals: 'dark' // Required scalar filter
    }
  }
});

// Other valid scalar filters for JSON fields
const examples = await prisma.user.findMany({
  where: {
    metadata: {
      path: ['settings', 'notifications'],
      not: false, // not filter
      // or: string_contains, string_starts_with, gt, gte, lt, lte, etc.
    }
  }
});

// schema.prisma
model User {
  id        Int      @id @default(autoincrement())
  age       Int
  email     String
  createdAt DateTime @default(now())
}

// ❌ WRONG - Type mismatches cause P2019
const user = await prisma.user.create({
  data: {
    age: "25",        // String instead of Int
    email: 12345,     // Number instead of String
    createdAt: "now"  // String instead of DateTime
  }
});

// ✅ CORRECT - Proper types
const user = await prisma.user.create({
  data: {
    age: 25,                    // Int
    email: '[email protected]',  // String
    createdAt: new Date()       // DateTime
  }
});

// schema.prisma
model Post {
  id        String   @id @default(cuid())
  title     String   // Required, no default
  content   String   // Required, no default
  published Boolean  @default(false)
  authorId  String   // Required, no default
}

// ❌ WRONG - Missing required fields
const post = await prisma.post.create({
  data: {
    title: 'My Post'
    // Missing content and authorId - causes P2019
  }
});

// ✅ CORRECT - All required fields provided
const post = await prisma.post.create({
  data: {
    title: 'My Post',
    content: 'Post content here',
    authorId: userId
    // published is optional (has default)
  }
});

import { Prisma } from '@prisma/client';

// Define a validator for user creation input
const userCreateInput = Prisma.validator<Prisma.UserCreateInput>()({
  email: '[email protected]',
  name: 'John Doe',
  age: 30
});

// Use the validated input
const user = await prisma.user.create({
  data: userCreateInput
});

// For dynamic data, combine with external validation libraries
import { z } from 'zod';

const userSchema = z.object({
  email: z.string().email(),
  name: z.string().min(1),
  age: z.number().int().positive()
});

// Validate user input before passing to Prisma
const validatedData = userSchema.parse(userInput);
const user = await prisma.user.create({
  data: validatedData
});

// ❌ WRONG - Field doesn't exist in schema
const users = await prisma.user.findMany({
  where: {
    userName: 'john' // Schema has 'username', not 'userName'
  },
  select: {
    id: true,
    fullName: true // Field doesn't exist
  }
});

// ✅ CORRECT - Use exact field names from schema
const users = await prisma.user.findMany({
  where: {
    username: 'john' // Matches schema field name
  },
  select: {
    id: true,
    name: true // Correct field name
  }
});

// TypeScript will help catch these errors if you use proper types
type UserWhereInput = Prisma.UserWhereInput;
const whereClause: UserWhereInput = {
  username: 'john' // TypeScript will error if field doesn't exist
};