diesel::expression_methods::TextOrNullableText seems to be missing for diesel::sql_types::Uuid

[Roms1383]

Hello, thanks for this wonderful library !

I ran this morning into an issue when trying to use like on table fields of type diesel::sql_types::Uuid.

Setup

Versions

• Rust: rustc 1.51.0 (2fd73fabe 2021-03-23)
• Diesel: 1.4.6
• Database: psql (PostgreSQL) 13.2
• Operating System

Feature Flags

• diesel: ["postgres", "chrono", "r2d2", "uuidv07", "numeric"]

Problem Description

When trying to use like or ilike (for Postgres) with a diesel table field of type Uuid, I run into the missing implementation of diesel::expression_methods::TextOrNullableText for diesel::sql_types::Uuid.

What are you trying to accomplish?

Just using LIKE filter on a query.

What is the expected output?

It should be able to filter diesel::sql_types::Uuid with LIKE.

What is the actual output?

Compilation error as shown above.

Are you seeing any additional errors?

None.

Steps to reproduce

# Cargo.toml
[dependencies]
diesel = { version = "1.4.5", features = ["postgres", "chrono", "r2d2", "uuidv07", "numeric"] }
uuid = { version = "0.8", features = ["serde", "v4"] }

// schema.rs
table! {
    use diesel::sql_types::*;
    my_table (id) {
        id -> Uuid,
    }
}

// querying like :
let mut query = my_table::table.into_boxed::<diesel::pg::Pg>();
query = query.filter(my_table::id.ilike("78621%"));
// or : query = query.filter(my_table::id.like("78621%"));
let results = query.load(&connection)?;

Checklist

• [x] I have already looked over the issue tracker
• [ ] I have already looked at the disussion forum for similar possible closed issues.
• [x] This issue can be reproduced on Rust's stable channel : stable-aarch64-apple-darwin (default)
• [ ] This issue can be reproduced without requiring a third party crate : requires at least uuid

Thanks :)

[Mingun]

diesel = { ... features = [..., "uuidv07", ...] }
uuid = { version = "0.8", ... }

Hm...

[Roms1383]

Yes @Mingun that's what I have already (please check the Cargo.toml excerpt).

[Roms1383]

@Mingun or do you mean remove the uuid dependency ?

[Mingun]

I mean that you probably need to use "uuid" feature of the diesel crate or use uuid with version <=0.7.

There are several closed issues in this repo with similar "trait not implemented" errors that connected with incompatible versions of dependencies

[Roms1383]

well if I switch to :

[dependencies]
diesel = { version = "1.4.5", features = ["postgres", "chrono", "r2d2", "uuidv07", "numeric"] } # <-- using uuid feature as before
uuid = { version = "0.6", features = ["serde", "v4"] } # <-- with 0.6 version here

The problem is then I end up with compilation errors like :

And :

I have also tried in that different setup :

diesel = { version = "1.4.6", features = ["postgres", "chrono", "r2d2", "uuid", "numeric"] }
uuid = { version = "0.8.2", features = ["serde", "v4"] }

By switching uuid's to_hyphenated() method to hyphenated() but then running into these compilation errors :

Or even :

diesel = { version = "1.4.6", features = ["postgres", "chrono", "r2d2", "uuid", "numeric"] }
uuid = { version = "0.6.5", features = ["serde", "v4"] }

But no matter which I'm still running into these compilation errors :

So I must admit that I'm a little bit confused here @Mingun.

[Roms1383]

@Mingun wouldn't it make sense to simply add :

impl TextOrNullableText for Uuid {}
impl TextOrNullableText for Nullable<Uuid> {}

to diesel::expression_methods::text_expression_methods ?

[weiznich]

@Roms1383 This error is expected as this would not generate valid SQL. Postgres does only support LIKE and similar operations on string types (so Text, VarChar and similar types). A expression of the type Uuid is not supported as left hand side of a LIKE expression. See the postgres documentation for details.

Closed as everything works as expected, which means in this case we turned a runtime error in your SQL query into a compile time error.

@Mingun That's totally unrelated to the uuid version and so on

[Roms1383]

@Mingun Ok, is there another way to go to implement a LIKE or ILIKE search on a partial string representation of Uuid parameter ? e.g. ... WHERE id LIKE '2127%'

[weiznich]

@Roms1383 To make that clear: @Mingun Is not related to the diesel project in any way. They are just a person that commented on this issue trying to help you. Otherwise our issue tracker is not the right place to ask questions please use any of the other support variants for this.

[Roms1383]

Ok thanks @weiznich I'm gonna look into it