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NULL JSON field fails to Scan into json.RawMessage #3373

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Jille opened this issue May 10, 2024 · 2 comments · May be fixed by #3778
Open

NULL JSON field fails to Scan into json.RawMessage #3373

Jille opened this issue May 10, 2024 · 2 comments · May be fixed by #3778
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bug Something isn't working

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@Jille
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Jille commented May 10, 2024

Version

1.26.0

What happened?

I have a MariaDB table with a nullable JSON column but selecting it when the value is NULL fails to Scan() it into the field.

I'm using the github.com/go-sql-driver/mysql driver.

Relevant log output

sql: Scan error on column index 1, name "my_json_column": unsupported Scan, storing driver.Value type <nil> into type *json.RawMessage


### Database schema

```sql
CREATE TABLE authors (
  id   INT PRIMARY KEY,
  bio  JSON
);

SQL queries

-- name: GetAuthor :one
SELECT * FROM authors WHERE id = ?;

Configuration

No response

Playground URL

https://play.sqlc.dev/p/8e1085762b38b90fb51da2bdac5fe4d2b37d6b89cfae5562063e295d3a829a18

What operating system are you using?

Linux

What database engines are you using?

MySQL

What type of code are you generating?

Go
@Jille Jille added bug Something isn't working triage New issues that hasn't been reviewed labels May 10, 2024
@Jille Jille changed the title NULL JOSN NULL JSON field fails to Scan into json.RawMessage May 10, 2024
@kyleconroy kyleconroy removed the triage New issues that hasn't been reviewed label Aug 5, 2024
@jarri-abidi
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jarri-abidi commented Sep 2, 2024 •
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any plans to fix this @kyleconroy? if you can suggest how to do it, maybe i can try

@advait
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advait commented Jan 7, 2025 •
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The bug actually appears here where we fail to check for notNull in json fields.

In my testing, it seems if we output *.json.RawMessage for nullable fields, the Scan operation succeeds successfully for null values.

I don't see any other references of pointers inside of sqlc-generated code (vs. explicit NullRawMessage types as exist in the postgres implementation) so I'm uncertain pointers would be acceptable. In any case I'll spin up a PR shortly for discussion.

@advait advait linked a pull request Jan 7, 2025 that will close this issue
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Add support for nullable json fieds in MySQL. advait/sqlc
4 participants
@kyleconroy @Jille @advait @jarri-abidi