scythe_codegen/backends/
csharp_mysqlconnector.rs

1use std::fmt::Write;
2use std::path::Path;
3
4use scythe_backend::manifest::{BackendManifest, load_manifest};
5use scythe_backend::naming::{
6    enum_type_name, enum_variant_name, fn_name, row_struct_name, to_pascal_case,
7};
8use scythe_backend::types::resolve_type;
9
10use scythe_core::analyzer::{AnalyzedQuery, CompositeInfo, EnumInfo};
11use scythe_core::errors::{ErrorCode, ScytheError};
12use scythe_core::parser::QueryCommand;
13
14use crate::backend_trait::{CodegenBackend, ResolvedColumn, ResolvedParam};
15
16const DEFAULT_MANIFEST_TOML: &str = include_str!("../../manifests/csharp-mysqlconnector.toml");
17
18pub struct CsharpMysqlConnectorBackend {
19    manifest: BackendManifest,
20}
21
22impl CsharpMysqlConnectorBackend {
23    pub fn new(engine: &str) -> Result<Self, ScytheError> {
24        match engine {
25            "mysql" | "mariadb" => {}
26            _ => {
27                return Err(ScytheError::new(
28                    ErrorCode::InternalError,
29                    format!(
30                        "csharp-mysqlconnector only supports MySQL, got engine '{}'",
31                        engine
32                    ),
33                ));
34            }
35        }
36        let manifest_path = Path::new("backends/csharp-mysqlconnector/manifest.toml");
37        let manifest = if manifest_path.exists() {
38            load_manifest(manifest_path)
39                .map_err(|e| ScytheError::new(ErrorCode::InternalError, format!("manifest: {e}")))?
40        } else {
41            toml::from_str(DEFAULT_MANIFEST_TOML)
42                .map_err(|e| ScytheError::new(ErrorCode::InternalError, format!("manifest: {e}")))?
43        };
44        Ok(Self { manifest })
45    }
46}
47
48/// Map a neutral type to a MySqlDataReader method.
49fn reader_method(neutral_type: &str) -> &'static str {
50    match neutral_type {
51        "bool" => "GetBoolean",
52        "int16" => "GetInt16",
53        "int32" => "GetInt32",
54        "int64" => "GetInt64",
55        "float32" => "GetFloat",
56        "float64" => "GetDouble",
57        "string" | "json" | "inet" | "interval" | "uuid" => "GetString",
58        "decimal" => "GetDecimal",
59        "date" => "GetFieldValue<DateOnly>",
60        "time" | "time_tz" => "GetFieldValue<TimeOnly>",
61        "datetime" => "GetDateTime",
62        "datetime_tz" => "GetFieldValue<DateTimeOffset>",
63        _ => "GetValue",
64    }
65}
66
67/// Rewrite $1, $2, ... to @p1, @p2, ...
68fn rewrite_params(sql: &str) -> String {
69    let mut result = sql.to_string();
70    for i in (1..=99).rev() {
71        let from = format!("${}", i);
72        let to = format!("@p{}", i);
73        result = result.replace(&from, &to);
74    }
75    result
76}
77
78/// Build the expression to read a column from MySqlDataReader.
79fn column_read_expr(col: &ResolvedColumn, ordinal: usize) -> String {
80    if col.neutral_type.starts_with("enum::") {
81        format!(
82            "(Enum.TryParse<{typ}>(reader.GetString({ord}), true, out var enumVal{ord}) ? enumVal{ord} : throw new InvalidOperationException($\"Invalid enum value '{{reader.GetString({ord})}}' for {typ}\"))",
83            typ = col.lang_type,
84            ord = ordinal
85        )
86    } else {
87        let method = reader_method(&col.neutral_type);
88        format!("reader.{}({})", method, ordinal)
89    }
90}
91
92impl CodegenBackend for CsharpMysqlConnectorBackend {
93    fn name(&self) -> &str {
94        "csharp-mysqlconnector"
95    }
96
97    fn manifest(&self) -> &scythe_backend::manifest::BackendManifest {
98        &self.manifest
99    }
100
101    fn supported_engines(&self) -> &[&str] {
102        &["mysql"]
103    }
104
105    fn file_header(&self) -> String {
106        "// Auto-generated by scythe. Do not edit.\nusing MySqlConnector;\n\npublic static class Queries {"
107            .to_string()
108    }
109
110    fn file_footer(&self) -> String {
111        "}".to_string()
112    }
113
114    fn generate_row_struct(
115        &self,
116        query_name: &str,
117        columns: &[ResolvedColumn],
118    ) -> Result<String, ScytheError> {
119        let struct_name = row_struct_name(query_name, &self.manifest.naming);
120        let mut out = String::new();
121        let _ = writeln!(out, "public record {}(", struct_name);
122        for (i, c) in columns.iter().enumerate() {
123            let field = to_pascal_case(&c.field_name);
124            let sep = if i + 1 < columns.len() { "," } else { "" };
125            let _ = writeln!(out, "    {} {}{}", c.full_type, field, sep);
126        }
127        let _ = write!(out, ");");
128        Ok(out)
129    }
130
131    fn generate_model_struct(
132        &self,
133        table_name: &str,
134        columns: &[ResolvedColumn],
135    ) -> Result<String, ScytheError> {
136        let name = to_pascal_case(table_name);
137        self.generate_row_struct(&name, columns)
138    }
139
140    fn generate_query_fn(
141        &self,
142        analyzed: &AnalyzedQuery,
143        struct_name: &str,
144        columns: &[ResolvedColumn],
145        params: &[ResolvedParam],
146    ) -> Result<String, ScytheError> {
147        let func_name = fn_name(&analyzed.name, &self.manifest.naming);
148        let sql = rewrite_params(&super::clean_sql_oneline_with_optional(
149            &analyzed.sql,
150            &analyzed.optional_params,
151            &analyzed.params,
152        ));
153        let mut out = String::new();
154
155        let param_list = params
156            .iter()
157            .map(|p| format!("{} {}", p.full_type, p.field_name))
158            .collect::<Vec<_>>()
159            .join(", ");
160        let sep = if param_list.is_empty() { "" } else { ", " };
161
162        // Handle :batch separately
163        if matches!(analyzed.command, QueryCommand::Batch) {
164            let batch_fn_name = format!("{}Batch", func_name);
165            if params.len() > 1 {
166                let params_record_name = format!("{}BatchParams", to_pascal_case(&analyzed.name));
167                let _ = writeln!(out, "public record {}(", params_record_name);
168                for (i, p) in params.iter().enumerate() {
169                    let field = to_pascal_case(&p.field_name);
170                    let sep = if i + 1 < params.len() { "," } else { "" };
171                    let _ = writeln!(out, "    {} {}{}", p.full_type, field, sep);
172                }
173                let _ = writeln!(out, ");");
174                let _ = writeln!(out);
175                let _ = writeln!(
176                    out,
177                    "public static async Task {}(MySqlConnection conn, List<{}> items) {{",
178                    batch_fn_name, params_record_name
179                );
180            } else if params.len() == 1 {
181                let _ = writeln!(
182                    out,
183                    "public static async Task {}(MySqlConnection conn, List<{}> items) {{",
184                    batch_fn_name, params[0].full_type
185                );
186            } else {
187                let _ = writeln!(
188                    out,
189                    "public static async Task {}(MySqlConnection conn, int count) {{",
190                    batch_fn_name
191                );
192            }
193            let _ = writeln!(
194                out,
195                "    await using var tx = await conn.BeginTransactionAsync();"
196            );
197            let _ = writeln!(out, "    try {{");
198            if params.is_empty() {
199                let _ = writeln!(out, "        for (int i = 0; i < count; i++) {{");
200            } else {
201                let _ = writeln!(out, "        foreach (var item in items) {{");
202            }
203            let _ = writeln!(
204                out,
205                "            await using var cmd = new MySqlCommand(\"{}\", conn, (MySqlTransaction)tx);",
206                sql
207            );
208            for (i, p) in params.iter().enumerate() {
209                let value_expr = if params.len() > 1 {
210                    let field = to_pascal_case(&p.field_name);
211                    format!("item.{}", field)
212                } else {
213                    "item".to_string()
214                };
215                let _ = writeln!(
216                    out,
217                    "            cmd.Parameters.AddWithValue(\"@p{}\", {});",
218                    i + 1,
219                    value_expr
220                );
221            }
222            let _ = writeln!(out, "            await cmd.ExecuteNonQueryAsync();");
223            let _ = writeln!(out, "        }}");
224            let _ = writeln!(out, "        await tx.CommitAsync();");
225            let _ = writeln!(out, "    }} catch {{");
226            let _ = writeln!(out, "        await tx.RollbackAsync();");
227            let _ = writeln!(out, "        throw;");
228            let _ = writeln!(out, "    }}");
229            let _ = write!(out, "}}");
230            return Ok(out);
231        }
232
233        let return_type = match &analyzed.command {
234            QueryCommand::One => format!("{}?", struct_name),
235            QueryCommand::Many => {
236                format!("List<{}>", struct_name)
237            }
238            QueryCommand::Exec => "void".to_string(),
239            QueryCommand::ExecResult | QueryCommand::ExecRows => "int".to_string(),
240            QueryCommand::Batch => unreachable!(),
241        };
242
243        let is_async_void = return_type == "void";
244        let task_type = if is_async_void {
245            "Task".to_string()
246        } else {
247            format!("Task<{}>", return_type)
248        };
249
250        let _ = writeln!(
251            out,
252            "public static async {} {}(MySqlConnection conn{}{}) {{",
253            task_type, func_name, sep, param_list
254        );
255
256        let _ = writeln!(
257            out,
258            "    await using var cmd = new MySqlCommand(\"{}\", conn);",
259            sql
260        );
261        for (i, p) in params.iter().enumerate() {
262            let value_expr = if p.neutral_type.starts_with("enum::") {
263                format!("{}.ToString().ToLower()", p.field_name)
264            } else {
265                p.field_name.clone()
266            };
267            let _ = writeln!(
268                out,
269                "    cmd.Parameters.AddWithValue(\"@p{}\", {});",
270                i + 1,
271                value_expr
272            );
273        }
274
275        match &analyzed.command {
276            QueryCommand::One => {
277                let _ = writeln!(
278                    out,
279                    "    await using var reader = await cmd.ExecuteReaderAsync();"
280                );
281                let _ = writeln!(out, "    if (!await reader.ReadAsync()) return null;");
282                let _ = writeln!(out, "    return new {}(", struct_name);
283                for (i, col) in columns.iter().enumerate() {
284                    let expr = column_read_expr(col, i);
285                    let sep = if i + 1 < columns.len() { "," } else { "" };
286                    if col.nullable {
287                        let _ = writeln!(out, "        reader.IsDBNull({i}) ? null : {expr}{sep}");
288                    } else {
289                        let _ = writeln!(out, "        {expr}{sep}");
290                    }
291                }
292                let _ = writeln!(out, "    );");
293            }
294            QueryCommand::Many => {
295                let _ = writeln!(
296                    out,
297                    "    await using var reader = await cmd.ExecuteReaderAsync();"
298                );
299                let _ = writeln!(out, "    var results = new List<{}>();", struct_name);
300                let _ = writeln!(out, "    while (await reader.ReadAsync()) {{");
301                let _ = writeln!(out, "        results.Add(new {}(", struct_name);
302                for (i, col) in columns.iter().enumerate() {
303                    let expr = column_read_expr(col, i);
304                    let sep = if i + 1 < columns.len() { "," } else { "" };
305                    if col.nullable {
306                        let _ =
307                            writeln!(out, "            reader.IsDBNull({i}) ? null : {expr}{sep}");
308                    } else {
309                        let _ = writeln!(out, "            {expr}{sep}");
310                    }
311                }
312                let _ = writeln!(out, "        ));");
313                let _ = writeln!(out, "    }}");
314                let _ = writeln!(out, "    return results;");
315            }
316            QueryCommand::Exec => {
317                let _ = writeln!(out, "    await cmd.ExecuteNonQueryAsync();");
318            }
319            QueryCommand::ExecResult | QueryCommand::ExecRows => {
320                let _ = writeln!(out, "    return await cmd.ExecuteNonQueryAsync();");
321            }
322            QueryCommand::Batch => unreachable!(),
323        }
324
325        let _ = write!(out, "}}");
326        Ok(out)
327    }
328
329    fn generate_enum_def(&self, enum_info: &EnumInfo) -> Result<String, ScytheError> {
330        let type_name = enum_type_name(&enum_info.sql_name, &self.manifest.naming);
331        let mut out = String::new();
332        let _ = writeln!(out, "public enum {} {{", type_name);
333        for value in &enum_info.values {
334            let variant = enum_variant_name(value, &self.manifest.naming);
335            let _ = writeln!(out, "    {},", variant);
336        }
337        let _ = write!(out, "}}");
338        Ok(out)
339    }
340
341    fn generate_composite_def(&self, composite: &CompositeInfo) -> Result<String, ScytheError> {
342        let name = to_pascal_case(&composite.sql_name);
343        let mut out = String::new();
344        if composite.fields.is_empty() {
345            let _ = writeln!(out, "public record {}();", name);
346        } else {
347            let _ = writeln!(out, "public record {}(", name);
348            for (i, field) in composite.fields.iter().enumerate() {
349                let cs_type = resolve_type(&field.neutral_type, &self.manifest, false)
350                    .map(|t| t.into_owned())
351                    .unwrap_or_else(|_| "object".to_string());
352                let field_name = to_pascal_case(&field.name);
353                let sep = if i + 1 < composite.fields.len() {
354                    ","
355                } else {
356                    ""
357                };
358                let _ = writeln!(out, "    {} {}{}", cs_type, field_name, sep);
359            }
360            let _ = write!(out, ");");
361        }
362        Ok(out)
363    }
364}
scythe_codegen/backends/csharp_mysqlconnector.rs

scythe_codegen/backends/
csharp_mysqlconnector.rs
