{"componentChunkName":"component---src-templates-post-template-js","path":"/posts/mongoose-to-typeorm-equivalent-of-pre-save-in-typeorm","result":{"data":{"markdownRemark":{"id":"0b329b77-760c-5dec-ad15-79db01e506ec","html":"

I have a code where I create a user and hash the password before saving.

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userSchema.pre('save', async function(next) {\n  const user = this;\n  if (user.isModified('password')) {\n    user.password = await brcrypt.hash(user.password, BCRYPT_HASH_ROUND);\n  }\n  next();\n});
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The userSchema could be any data model but the interesting part here is the pre('save'), ...

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Lately, I’ve been playing around with Nestjs to use for my next project and I was trying to implement a user management with it.

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Here’s my code when adding a new user

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import { Repository, EntityRepository } from 'typeorm';\nimport { User } from './user.entity';\nimport { UserCredentialsDto } from './dto/user-credentials.dto';\nimport * as bcrypt from 'bcryptjs';\nconst BCRYPT_HASH_ROUND = 8;\n\n@EntityRepository(User)\nexport class UserRepository extends Repository<User> {\n  async add(userCredentialsDTO: UserCredentialsDto): Promise<any> {\n    const { email, password } = userCredentialsDTO;\n    const user = new User();\n    user.email = email;\n    user.password = await bcrypt.hash(this.password, BCRYPT_HASH_ROUND);\n    try {\n       return await user.save();\n    } catch (e) {\n      if (e.code === '23505') {\n        throw new Error('Email already exists');\n      }\n    }\n  }\n}
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In my code, I’m hashing the password explicity before executing the user.save() method. I want what I have in mongoose where I tapped in the pre-save event and hash the password from there.

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To do this, I just need to use @BeforeInsert listener on my user entity like this

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import {\n  BaseEntity,\n  Entity,\n  PrimaryGeneratedColumn,\n  Column,\n  BeforeInsert,\n} from 'typeorm';\nimport * as bcrypt from 'bcryptjs';\nconst BCRYPT_HASH_ROUND = 8;\n\n@Entity()\nexport class User extends BaseEntity {\n  @PrimaryGeneratedColumn()\n  id: number;\n\n  @Column({ unique: true, length: 256 })\n  email: string;\n\n  @Column()\n  password: string;\n\n  @BeforeInsert()\n  async beforeInsert() {\n    this.password = await bcrypt.hash(this.password, BCRYPT_HASH_ROUND);\n  }\n  // imagine more code below\n  ....
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Another benefit with this approach would be that the UserRepository doesn’t need to know anything about bcryptjs!

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#TodayILearned

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