use scythe_backend::manifest::BackendManifest;
use scythe_backend::naming::{
enum_type_name, enum_variant_name, fn_name, row_struct_name, to_pascal_case, to_snake_case,
};
use std::fmt::Write;
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");
const DEFAULT_MANIFEST_REDSHIFT: &str = include_str!("../../manifests/elixir-postgrex.redshift.toml");
pub struct ElixirPostgrexBackend {
manifest: BackendManifest,
}
impl ElixirPostgrexBackend {
pub fn new(engine: &str) -> Result<Self, ScytheError> {
let default_toml = match engine {
"postgresql" | "postgres" | "pg" => DEFAULT_MANIFEST_TOML,
"redshift" => DEFAULT_MANIFEST_REDSHIFT,
_ => {
return Err(ScytheError::new(
ErrorCode::InternalError,
format!(
"elixir-postgrex only supports PostgreSQL/Redshift, got engine '{}'",
engine
),
));
}
};
let manifest = super::parse_manifest(default_toml)?;
Ok(Self { manifest })
}
}
impl CodegenBackend for ElixirPostgrexBackend {
fn name(&self) -> &str {
"elixir-postgrex"
}
fn manifest(&self) -> &scythe_backend::manifest::BackendManifest {
&self.manifest
}
fn supported_engines(&self) -> &[&str] {
&["postgresql", "redshift"]
}
fn query_class_header(&self) -> String {
"defmodule Scythe.Queries do".to_string()
}
fn file_footer(&self) -> String {
"end".to_string()
}
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 | QueryCommand::Opt => {
let _ = writeln!(
out,
"@spec {}(Postgrex.conn(){}) :: {{:ok, %{}{{}}}} | {{:error, :not_found}} | {{: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,
" case Postgrex.query(tx_conn, \"{}\", Tuple.to_list(item)) do",
sql
);
} else if params.len() == 1 {
let _ = writeln!(out, " case Postgrex.query(tx_conn, \"{}\", [item]) do", sql);
} else {
let _ = writeln!(out, " case Postgrex.query(tx_conn, \"{}\", []) do", sql);
}
let _ = writeln!(out, " {{:ok, _}} -> :ok");
let _ = writeln!(out, " {{:error, err}} -> DBConnection.rollback(tx_conn, err)");
let _ = writeln!(out, " end");
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 queries are routed to generate_grouped_query_fn")
}
}
let _ = writeln!(out, "def {}(conn{}{}) do", func_name, sep, param_list);
match &analyzed.command {
QueryCommand::One | QueryCommand::Opt => {
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)
}
fn generate_grouped_structs(
&self,
parent_struct_name: &str,
child_struct_name: &str,
parent_columns: &[ResolvedColumn],
child_columns: &[ResolvedColumn],
_key_column: &str,
) -> Result<String, ScytheError> {
let mut out = String::new();
let _ = writeln!(out, "defmodule {} do", child_struct_name);
let _ = writeln!(out, " @moduledoc \"Child row type for grouped query.\"");
let _ = writeln!(out);
let _ = writeln!(out, " @type t :: %__MODULE__{{");
for (i, c) in child_columns.iter().enumerate() {
let sep = if i + 1 < child_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 child_fields = child_columns
.iter()
.map(|c| format!(":{}", c.field_name))
.collect::<Vec<_>>()
.join(", ");
let _ = writeln!(out, " defstruct [{}]", child_fields);
let _ = writeln!(out, "end");
let _ = writeln!(out);
let _ = writeln!(out, "defmodule {} do", parent_struct_name);
let _ = writeln!(out, " @moduledoc \"Parent row type for grouped query.\"");
let _ = writeln!(out);
let _ = writeln!(out, " @type t :: %__MODULE__{{");
for c in parent_columns.iter() {
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);
}
let _ = writeln!(out, " children: [{}.t()]", child_struct_name);
let _ = writeln!(out, " }}");
let parent_fields = parent_columns
.iter()
.map(|c| format!(":{}", c.field_name))
.collect::<Vec<_>>()
.join(", ");
let _ = writeln!(out, " defstruct [{}, :children]", parent_fields);
let _ = write!(out, "end");
Ok(out)
}
fn generate_grouped_query_fn(
&self,
request: &crate::backend_trait::GroupedQueryFn<'_>,
) -> Result<String, ScytheError> {
let analyzed = request.analyzed;
let parent_struct_name = request.parent_struct_name;
let child_struct_name = request.child_struct_name;
let all_columns = request.all_columns;
let parent_columns = request.parent_columns;
let child_columns = request.child_columns;
let params = request.params;
let key_column = request.key_column;
let func_name = fn_name(&analyzed.name, &self.manifest.naming);
let key_field = to_snake_case(key_column);
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 {
format!(
", {}",
params
.iter()
.map(|p| p.full_type.clone())
.collect::<Vec<_>>()
.join(", ")
)
};
let all_field_vars = all_columns
.iter()
.map(|c| c.field_name.clone())
.collect::<Vec<_>>()
.join(", ");
let child_struct_fields = child_columns
.iter()
.map(|c| format!("{}: {}", c.field_name, c.field_name))
.collect::<Vec<_>>()
.join(", ");
let parent_struct_fields = parent_columns
.iter()
.map(|c| format!("{}: {}", c.field_name, c.field_name))
.collect::<Vec<_>>()
.join(", ");
let child_init = format!("%{}{{{}}}", child_struct_name, child_struct_fields);
let parent_init = format!("%{}{{{}, children: [child]}}", parent_struct_name, parent_struct_fields);
let _ = writeln!(
out,
"@spec {}(Postgrex.conn(){}) :: {{:ok, [%{}{{}}]}} | {{:error, term()}}",
func_name, param_specs, parent_struct_name
);
let _ = writeln!(out, "def {}(conn{}{}) do", func_name, sep, param_list);
let _ = writeln!(out, " case Postgrex.query(conn, \"{}\", {}) do", sql, param_args);
let _ = writeln!(out, " {{:ok, %{{rows: rows}}}} ->");
let _ = writeln!(
out,
" {{order, acc}} = Enum.reduce(rows, {{[], %{{}}}}, fn row, {{order, acc}} ->"
);
let _ = writeln!(out, " [{}] = row", all_field_vars);
let _ = writeln!(out, " child = {}", child_init);
let _ = writeln!(out, " if Map.has_key?(acc, {}) do", key_field);
let _ = writeln!(
out,
" {{order, Map.update!(acc, {}, fn p -> %{{p | children: [child | p.children]}} end)}}",
key_field
);
let _ = writeln!(out, " else");
let _ = writeln!(out, " parent = {}", parent_init);
let _ = writeln!(
out,
" {{[{} | order], Map.put(acc, {}, parent)}}",
key_field, key_field
);
let _ = writeln!(out, " end");
let _ = writeln!(out, " end)");
let _ = writeln!(out, " result = Enum.map(Enum.reverse(order), fn key ->");
let _ = writeln!(out, " parent = Map.fetch!(acc, key)");
let _ = writeln!(out, " %{{parent | children: Enum.reverse(parent.children)}}");
let _ = writeln!(out, " end)");
let _ = writeln!(out, " {{:ok, result}}");
let _ = writeln!(out, " {{:error, err}} -> {{:error, err}}");
let _ = writeln!(out, " end");
let _ = write!(out, "end");
Ok(out)
}
}
#[cfg(test)]
mod tests {
use scythe_core::analyzer::{AnalyzedColumn, AnalyzedQuery, GroupByConfig};
use scythe_core::parser::QueryCommand;
use super::ElixirPostgrexBackend;
use crate::generate_with_backend;
fn make_grouped_query() -> AnalyzedQuery {
let parent_cols = vec![
AnalyzedColumn {
name: "id".to_string(),
neutral_type: "int32".to_string(),
nullable: false,
..Default::default()
},
AnalyzedColumn {
name: "name".to_string(),
neutral_type: "string".to_string(),
nullable: false,
..Default::default()
},
AnalyzedColumn {
name: "email".to_string(),
neutral_type: "string".to_string(),
nullable: false,
..Default::default()
},
];
let child_cols = vec![
AnalyzedColumn {
name: "order_id".to_string(),
neutral_type: "int32".to_string(),
nullable: false,
..Default::default()
},
AnalyzedColumn {
name: "total".to_string(),
neutral_type: "decimal".to_string(),
nullable: true,
..Default::default()
},
AnalyzedColumn {
name: "order_date".to_string(),
neutral_type: "datetime".to_string(),
nullable: false,
..Default::default()
},
];
let all_cols = [parent_cols.clone(), child_cols.clone()].concat();
AnalyzedQuery {
name: "GetUsersWithOrders".to_string(),
command: QueryCommand::Grouped,
sql: "SELECT u.id, u.name, u.email, o.id AS order_id, o.total, o.created_at AS order_date\n\
FROM users u JOIN orders o ON o.user_id = u.id"
.to_string(),
columns: all_cols,
params: vec![],
deprecated: None,
source_table: None,
composites: vec![],
enums: vec![],
optional_params: vec![],
group_by: Some(GroupByConfig {
table: "users".to_string(),
key_column: "id".to_string(),
parent_columns: parent_cols,
child_columns: child_cols,
}),
custom: vec![],
}
}
#[test]
fn test_grouped_postgrex_structs() {
let backend = ElixirPostgrexBackend::new("postgresql").unwrap();
let query = make_grouped_query();
let result = generate_with_backend(&query, &backend).unwrap();
let row_struct = result.row_struct.as_deref().unwrap();
assert!(
row_struct.contains("defmodule GetUsersWithOrdersChildRow do"),
"missing child defmodule; got:\n{row_struct}"
);
assert!(
row_struct.contains("order_id: integer()"),
"child struct missing order_id; got:\n{row_struct}"
);
assert!(
row_struct.contains("total: Decimal.t() | nil"),
"child struct missing nullable total; got:\n{row_struct}"
);
assert!(
row_struct.contains("defmodule GetUsersWithOrdersRow do"),
"missing parent defmodule; got:\n{row_struct}"
);
assert!(
row_struct.contains("id: integer()"),
"parent struct missing id; got:\n{row_struct}"
);
assert!(
row_struct.contains("children: [GetUsersWithOrdersChildRow.t()]"),
"parent struct missing children field; got:\n{row_struct}"
);
let child_pos = row_struct.find("GetUsersWithOrdersChildRow do").unwrap();
let parent_pos = row_struct.find("GetUsersWithOrdersRow do").unwrap();
assert!(child_pos < parent_pos, "child struct must appear before parent struct");
assert!(result.model_struct.is_none(), "grouped must not produce a model_struct");
}
#[test]
fn test_grouped_postgrex_query_fn() {
let backend = ElixirPostgrexBackend::new("postgresql").unwrap();
let query = make_grouped_query();
let result = generate_with_backend(&query, &backend).unwrap();
let query_fn = result.query_fn.as_deref().unwrap();
assert!(
query_fn.contains("def get_users_with_orders(conn) do"),
"missing fn head; got:\n{query_fn}"
);
assert!(
query_fn.contains("Postgrex.query(conn,"),
"fn must use Postgrex.query; got:\n{query_fn}"
);
assert!(
query_fn.contains("Enum.reduce(rows,"),
"fn must use Enum.reduce for fold; got:\n{query_fn}"
);
assert!(
query_fn.contains("Map.update!"),
"fn must use Map.update! to append children; got:\n{query_fn}"
);
assert!(
query_fn.contains("Enum.reverse(order)"),
"fn must reverse order list to restore insertion order; got:\n{query_fn}"
);
assert!(
query_fn.contains("{:ok, result}"),
"fn must return {{:ok, result}}; got:\n{query_fn}"
);
}
}