Incorrect data loading from JSON string for column type 'simple-json'. Why?

[MWarCZ]

Issue type:

[x] question
[x] bug report
[ ] feature request
[ ] documentation issue

Database system/driver:

[ ] cordova
[ ] mongodb
[ ] mssql
[x] mysql / mariadb
[ ] oracle
[ ] postgres
[ ] cockroachdb
[ ] sqlite
[ ] sqljs
[ ] react-native
[ ] expo

TypeORM version:

[x] latest
[ ] @next
[ ] 0.x.x (or put your version here)

Why are some correct JSON values returned as Object when typeorm loading JSON string (simple-json)?

JSON.parse('{"foo": "bar"}') // { foo: 'bar' }
JSON.parse('[ 1, 2, 3]') // [1, 2, 3]
JSON.parse('true') // true => But typeorm return: { }
JSON.parse('123') // 123 => But typeorm return: { }
JSON.parse('"message"') // 'message' => But typeorm return: { }

In my project, I noticed this strange behavior.

• Data inside entity is correct before saving.
• Inside database, data is also correct.
• But loaded entity has incorrect data.

Example - Part of my problem:

@Entity()
export class Foo {
  @Column('simple-json')
  returnValue: Json = false
} 

// ...

let foo = await connection.manager.save(new Foo())
// foo => Foo { returnValue: false }
// Inside DB => select 'foo'.'returnValue' from 'foo' => returnValue: "false"
let findFoo = await connection.getRepository(Foo).findOneOrFail()
// findFoo => Foo { returnValue: {} }

I looked into typeorm code and I found explicit test on type Object before returning parsed values.

Why is this behavior chosen?

[zhangyy91]

I met the same issue. According to the standards like RFC 7159, ECMA-404, ECMA-262, any JSON value is valid JSON text, including simple strings and numbers. But current behavior is against the standards and the official document,

simple-json which can store any values which can be stored in database via JSON.stringify

Hope this issue can be fixed quickly.

[wodka]

The error problem was introduced in pull request #4476

[zhangyy91]

@wodka Thank you for the information. I just got the pull request and found the cause. I think this issue can be fixed without much effort. According to the standards and documents, when retrieving simple-json columns, we can just use JSON.parse() to get the JSON value, if it fails, null should be returned.

static stringToSimpleJson(value: any) {
  try {
    return JSON.parse(value);
  } catch (err) {
    return null;
  }
}