use std::fmt::Write;
use std::path::Path;
use scythe_backend::manifest::{BackendManifest, load_manifest};
use scythe_backend::naming::{
enum_type_name, enum_variant_name, fn_name, row_struct_name, to_pascal_case, to_snake_case,
};
use scythe_core::analyzer::{AnalyzedQuery, CompositeInfo, EnumInfo};
use scythe_core::errors::{ErrorCode, ScytheError};
use scythe_core::parser::QueryCommand;
use crate::backend_trait::{CodegenBackend, ResolvedColumn, ResolvedParam};
const DEFAULT_MANIFEST_TOML: &str = include_str!("../../manifests/elixir-postgrex.toml");
pub struct ElixirPostgrexBackend {
manifest: BackendManifest,
}
impl ElixirPostgrexBackend {
pub fn new(engine: &str) -> Result<Self, ScytheError> {
match engine {
"postgresql" | "postgres" | "pg" => {}
_ => {
return Err(ScytheError::new(
ErrorCode::InternalError,
format!(
"elixir-postgrex only supports PostgreSQL, got engine '{}'",
engine
),
));
}
}
let manifest_path = Path::new("backends/elixir-postgrex/manifest.toml");
let manifest = if manifest_path.exists() {
load_manifest(manifest_path)
.map_err(|e| ScytheError::new(ErrorCode::InternalError, format!("manifest: {e}")))?
} else {
toml::from_str(DEFAULT_MANIFEST_TOML)
.map_err(|e| ScytheError::new(ErrorCode::InternalError, format!("manifest: {e}")))?
};
Ok(Self { manifest })
}
}
impl CodegenBackend for ElixirPostgrexBackend {
fn name(&self) -> &str {
"elixir-postgrex"
}
fn manifest(&self) -> &scythe_backend::manifest::BackendManifest {
&self.manifest
}
fn generate_row_struct(
&self,
query_name: &str,
columns: &[ResolvedColumn],
) -> Result<String, ScytheError> {
let struct_name = row_struct_name(query_name, &self.manifest.naming);
let mut out = String::new();
let _ = writeln!(out, "defmodule {} do", struct_name);
let _ = writeln!(out, " @moduledoc \"Row type for {} queries.\"", query_name);
let _ = writeln!(out);
let _ = writeln!(out, " @type t :: %__MODULE__{{");
for (i, c) in columns.iter().enumerate() {
let sep = if i + 1 < columns.len() { "," } else { "" };
let type_ref = if c.neutral_type.starts_with("enum::") {
format!("{}.t()", c.full_type)
} else {
c.full_type.clone()
};
let _ = writeln!(out, " {}: {}{}", c.field_name, type_ref, sep);
}
let _ = writeln!(out, " }}");
let fields = columns
.iter()
.map(|c| format!(":{}", c.field_name))
.collect::<Vec<_>>()
.join(", ");
let _ = writeln!(out, " defstruct [{}]", fields);
let _ = write!(out, "end");
Ok(out)
}
fn generate_model_struct(
&self,
table_name: &str,
columns: &[ResolvedColumn],
) -> Result<String, ScytheError> {
let name = to_pascal_case(table_name);
self.generate_row_struct(&name, columns)
}
fn generate_query_fn(
&self,
analyzed: &AnalyzedQuery,
struct_name: &str,
columns: &[ResolvedColumn],
params: &[ResolvedParam],
) -> Result<String, ScytheError> {
let func_name = fn_name(&analyzed.name, &self.manifest.naming);
let sql = super::clean_sql_with_optional(
&analyzed.sql,
&analyzed.optional_params,
&analyzed.params,
);
let mut out = String::new();
let param_list = params
.iter()
.map(|p| p.field_name.clone())
.collect::<Vec<_>>()
.join(", ");
let sep = if param_list.is_empty() { "" } else { ", " };
let param_args = if params.is_empty() {
"[]".to_string()
} else {
format!(
"[{}]",
params
.iter()
.map(|p| p.field_name.clone())
.collect::<Vec<_>>()
.join(", ")
)
};
let param_specs = if params.is_empty() {
String::new()
} else {
let specs: Vec<String> = params.iter().map(|p| p.full_type.clone()).collect();
format!(", {}", specs.join(", "))
};
match &analyzed.command {
QueryCommand::One => {
let _ = writeln!(
out,
"@spec {}(Postgrex.conn(){}) :: {{:ok, %{}{{}}}} | {{:error, term()}}",
func_name, param_specs, struct_name
);
}
QueryCommand::Many => {
let _ = writeln!(
out,
"@spec {}(Postgrex.conn(){}) :: {{:ok, [%{}{{}}]}} | {{:error, term()}}",
func_name, param_specs, struct_name
);
}
QueryCommand::Batch => {
let batch_fn_name = format!("{}_batch", func_name);
let _ = writeln!(
out,
"@spec {}(Postgrex.conn(), list()) :: :ok | {{:error, term()}}",
batch_fn_name
);
let _ = writeln!(out, "def {}(conn, items) do", batch_fn_name);
let _ = writeln!(out, " Postgrex.transaction(conn, fn tx_conn ->");
let _ = writeln!(out, " Enum.each(items, fn item ->");
if params.len() > 1 {
let _ = writeln!(
out,
" Postgrex.query!(tx_conn, \"{}\", Tuple.to_list(item))",
sql
);
} else if params.len() == 1 {
let _ = writeln!(out, " Postgrex.query!(tx_conn, \"{}\", [item])", sql);
} else {
let _ = writeln!(out, " Postgrex.query!(tx_conn, \"{}\", [])", sql);
}
let _ = writeln!(out, " end)");
let _ = writeln!(out, " end)");
let _ = write!(out, "end");
return Ok(out);
}
QueryCommand::Exec => {
let _ = writeln!(
out,
"@spec {}(Postgrex.conn(){}) :: :ok | {{:error, term()}}",
func_name, param_specs
);
}
QueryCommand::ExecResult | QueryCommand::ExecRows => {
let _ = writeln!(
out,
"@spec {}(Postgrex.conn(){}) :: {{:ok, non_neg_integer()}} | {{:error, term()}}",
func_name, param_specs
);
}
QueryCommand::Grouped => {
unreachable!("Grouped is rewritten to Many before codegen")
}
}
let _ = writeln!(out, "def {}(conn{}{}) do", func_name, sep, param_list);
match &analyzed.command {
QueryCommand::One => {
let _ = writeln!(
out,
" case Postgrex.query(conn, \"{}\", {}) do",
sql, param_args
);
let _ = writeln!(out, " {{:ok, %{{rows: [row]}}}} ->");
let field_vars = columns
.iter()
.map(|c| c.field_name.clone())
.collect::<Vec<_>>()
.join(", ");
let _ = writeln!(out, " [{}] = row", field_vars);
let struct_fields = columns
.iter()
.map(|c| format!("{}: {}", c.field_name, c.field_name))
.collect::<Vec<_>>()
.join(", ");
let _ = writeln!(out, " {{:ok, %{}{{{}}}}}", struct_name, struct_fields);
let _ = writeln!(out, " {{:ok, %{{rows: []}}}} -> {{:error, :not_found}}");
let _ = writeln!(out, " {{:error, err}} -> {{:error, err}}");
let _ = writeln!(out, " end");
}
QueryCommand::Many => {
let _ = writeln!(
out,
" case Postgrex.query(conn, \"{}\", {}) do",
sql, param_args
);
let _ = writeln!(out, " {{:ok, %{{rows: rows}}}} ->");
let field_vars = columns
.iter()
.map(|c| c.field_name.clone())
.collect::<Vec<_>>()
.join(", ");
let struct_fields = columns
.iter()
.map(|c| format!("{}: {}", c.field_name, c.field_name))
.collect::<Vec<_>>()
.join(", ");
let _ = writeln!(out, " results = Enum.map(rows, fn row ->");
let _ = writeln!(out, " [{}] = row", field_vars);
let _ = writeln!(out, " %{}{{{}}}", struct_name, struct_fields);
let _ = writeln!(out, " end)");
let _ = writeln!(out, " {{:ok, results}}");
let _ = writeln!(out, " {{:error, err}} -> {{:error, err}}");
let _ = writeln!(out, " end");
}
QueryCommand::Exec => {
let _ = writeln!(
out,
" case Postgrex.query(conn, \"{}\", {}) do",
sql, param_args
);
let _ = writeln!(out, " {{:ok, _}} -> :ok");
let _ = writeln!(out, " {{:error, err}} -> {{:error, err}}");
let _ = writeln!(out, " end");
}
QueryCommand::ExecResult | QueryCommand::ExecRows => {
let _ = writeln!(
out,
" case Postgrex.query(conn, \"{}\", {}) do",
sql, param_args
);
let _ = writeln!(out, " {{:ok, %{{num_rows: n}}}} -> {{:ok, n}}");
let _ = writeln!(out, " {{:error, err}} -> {{:error, err}}");
let _ = writeln!(out, " end");
}
QueryCommand::Batch | QueryCommand::Grouped => unreachable!(),
}
let _ = write!(out, "end");
Ok(out)
}
fn generate_enum_def(&self, enum_info: &EnumInfo) -> Result<String, ScytheError> {
let type_name = enum_type_name(&enum_info.sql_name, &self.manifest.naming);
let mut out = String::new();
let _ = writeln!(out, "defmodule {} do", type_name);
let _ = writeln!(
out,
" @moduledoc \"Enum type for {}.\"",
enum_info.sql_name
);
let _ = writeln!(out);
let _ = writeln!(out, " @type t :: String.t()");
let _ = writeln!(out);
for value in &enum_info.values {
let variant = enum_variant_name(value, &self.manifest.naming);
let _ = writeln!(out, " @spec {}() :: String.t()", to_snake_case(&variant));
let _ = writeln!(
out,
" def {}(), do: \"{}\"",
to_snake_case(&variant),
value
);
}
let values_list = enum_info
.values
.iter()
.map(|v| format!("\"{}\"", v))
.collect::<Vec<_>>()
.join(", ");
let _ = writeln!(out, " @spec values() :: [String.t()]");
let _ = writeln!(out, " def values, do: [{}]", values_list);
let _ = write!(out, "end");
Ok(out)
}
fn generate_composite_def(&self, composite: &CompositeInfo) -> Result<String, ScytheError> {
let name = to_pascal_case(&composite.sql_name);
let mut out = String::new();
let _ = writeln!(out, "defmodule {} do", name);
let _ = writeln!(
out,
" @moduledoc \"Composite type for {}.\"",
composite.sql_name
);
let _ = writeln!(out);
if composite.fields.is_empty() {
let _ = writeln!(out, " @type t :: %__MODULE__{{}}");
} else {
let _ = writeln!(out, " @type t :: %__MODULE__{{");
for (i, f) in composite.fields.iter().enumerate() {
let sep = if i + 1 < composite.fields.len() {
","
} else {
""
};
let _ = writeln!(out, " {}: term(){}", to_snake_case(&f.name), sep);
}
let _ = writeln!(out, " }}");
}
let _ = writeln!(out);
if composite.fields.is_empty() {
let _ = writeln!(out, " defstruct []");
} else {
let fields = composite
.fields
.iter()
.map(|f| format!(":{}", to_snake_case(&f.name)))
.collect::<Vec<_>>()
.join(", ");
let _ = writeln!(out, " defstruct [{}]", fields);
}
let _ = write!(out, "end");
Ok(out)
}
}