Can't use postgresql-service

[Iam-WenYi]

Describe the bug

The example code gived in postgresql's service markfodown document can't run.

Steps to Reproduce

1. Make a copy of ofs directory, rename to postgresql-opendal-try/
2. Chanage Cargo.toml to this:

# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.

[package]
categories = ["postgresql-service-example"]
description = "OpenDAL PostgreSQL Service Example"
keywords = ["storage", "data", "postgresql"]
name = "postgresql-service-example"
version = "0.0.1"

authors = ["Wen Yi <wen-yi@qq.com>"]
edition = "2021"
homepage = "https://opendal.apache.org/"
license = "Apache-2.0"
repository = "https://github.com/apache/opendal"
rust-version = "1.80"

[dependencies]
anyhow = { version = "1" }
clap = { version = "4.5.21", features = ["derive", "env"] }
log = { version = "0.4.22" }
logforth = { version = "0.23.1", default-features = false }
opendal = { version = "0.53.0", path = "../../core" }
tokio = { version = "1.37.0", features = [
  "fs",
  "macros",
  "rt-multi-thread",
  "io-std",
  "signal",
] }
url = { version = "2.5.4" }

[target.'cfg(any(target_os = "linux", target_os = "freebsd", target_os = "macos"))'.dependencies]
fuse3 = { version = "0.8.1", "features" = ["tokio-runtime", "unprivileged"] }
fuse3_opendal = { version = "0.0.14", path = "../../integrations/fuse3" }
libc = "0.2.154"
nix = { version = "0.29.0", features = ["user"] }

[target.'cfg(target_os = "windows")'.dependencies]
cloud-filter = { version = "0.0.5" }
cloud_filter_opendal = { version = "0.0.7", path = "../../integrations/cloud_filter" }

[features]
default = ["services-fs", "services-s3"]
services-fs = ["opendal/services-fs"]
services-s3 = ["opendal/services-s3"]

[dev-dependencies]
opendal = { version = "0.53.0", path = "../../core", features = ["tests"] }
tempfile = "3.16.0"
test-context = "0.4.1"
walkdir = "2.5.0"

3. Change main.rs to this:

use anyhow::Result;
use opendal::services::Postgresql;
use opendal::Operator;

#[tokio::main]
async fn main() -> Result<()> {
    let mut builder = Postgresql::default()
        .root("/")
        .connection_string("postgresql://you_username:your_password@127.0.0.1:5432/your_database")
        .table("your_table")
        // key field type in the table should be compatible with Rust's &str like text
        .key_field("key")
        // value field type in the table should be compatible with Rust's Vec<u8> like bytea
        .value_field("value");

    let op = Operator::new(builder)?.finish();
    Ok(())
}

4. Cargo build

Expected Behavior

I want to use the OpenDAL to connect to the postgresql, but I can't

Additional Context

No response

Are you willing to submit a PR to fix this bug?

• Yes, I would like to submit a PR.

[Xuanwo]

Hi, @Iam-WenYi, as suggested in the error message: opendal::services::Postgresql is a different thing from opendal::Scheme::Postgersql. Please don't mix use them.

[Xuanwo]

Also, OpenDAL doesn't enable all services by default. Instead, it uses features to select which services to use. So, you'll also need to make sure that pg has been enabled, like this:

opendal = { version = "0.53.0", path = "../../core", features = ["services-postgresql"] }

And the last thing, opendal rust core (core) and oli are differnt projects.

Make a copy of ofs directory, rename to postgresql-opendal-try/

Doesn't make sense to me.