codegen: slop out an AST generator for 'checkForeignKeyErrors' in 'SaveXyz()'

doc/TODO.txt

@@ -15,3 +15,17 @@ TODO: generator-foreign-keys
 TODO: migration-structs
 - Right now, migrations are strings.  Could be a struct with "name", "up" and "down" fields
 - Adding a "down" operation enables handling newer DB versions with "down instead of error-out" for development (perhaps a flag)
+
+IDEA: migrations-table
+- Store migrations in a table.  This makes the schema more self-documenting.
+- Possible schema: name, sql_up, sql_down, hash (computed from those fields plus previous migration hash)
+    - or just rowid instead of hash?  Migration sequence should be immutable after publishing, so there should never be "conflicts"
+
+TODO: language-server-for-TODO.txt
+
+TODO: auto-migration-checker
+- Use `pkg/schema` to test whether a base schema plus a migration equals a new schema
+
+TODO: codegen `without rowid` tables properly
+
+TODO: generated test file inclues global test DB setup, which is wrong

ops/devcontainer/Dockerfile

@@ -10,6 +10,8 @@ RUN apk add less
 RUN curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b /usr/local/bin v2.0.2
 RUN GOBIN=/usr/local/bin go install git.offline-twitter.com/offline-labs/gocheckout@v0.0.2
 
+COPY etc/group /etc/group
+
 # Create a user in the container with the same UID as on the host machine, to avoid ownership conflicts.
 # The user gets sudo of course.
 #

ops/devcontainer/etc/group

@@ -0,0 +1,3 @@
+root:x:0:
+nogroup:x:65533:
+nobody:x:65534:

ops/gas_init_test.sh

@@ -31,9 +31,12 @@ cd $test_project
 
 # Create a new table in the schema
 cat >> pkg/db/schema.sql <<EOF
+create table item_flavor (rowid integer primary key, name text not null) strict;
+
 create table items (
     rowid integer primary key,
-    description text not null default ''
+    description text not null default '',
+    flavor integer references item_flavor(rowid)
 ) strict;
 EOF
 

pkg/codegen/modelgenerate/generate_model.go

@@ -21,6 +21,14 @@ func GenerateIDType(table schema.Table) *ast.GenDecl {
 	}
 }
 
+func fkFieldName(col schema.Column) string {
+	if col.IsNonCodeTableForeignKey() {
+		return textutils.SnakeToCamel(strings.TrimSuffix(col.Name, "_id")) + "ID"
+	} else {
+		return textutils.SnakeToCamel(col.Name)
+	}
+}
+
 // GenerateModelAST produces an AST for a struct type corresponding to the model.
 // TODO: generate the right field types here based on column types.
 func GenerateModelAST(table schema.Table) *ast.GenDecl {
@@ -37,9 +45,9 @@ func GenerateModelAST(table schema.Table) *ast.GenDecl {
 				Tag:   &ast.BasicLit{Kind: token.STRING, Value: "`db:\"rowid\" json:\"id\"`"},
 			})
 		default:
-			if col.IsForeignKey && strings.HasSuffix(col.Name, "_id") {
+			if col.IsNonCodeTableForeignKey() {
 				fields = append(fields, &ast.Field{
-					Names: []*ast.Ident{ast.NewIdent(textutils.SnakeToCamel(strings.TrimSuffix(col.Name, "_id")) + "ID")},
+					Names: []*ast.Ident{ast.NewIdent(fkFieldName(col))},
 					Type:  ast.NewIdent(schema.TypenameFromTablename(col.ForeignKeyTargetTable) + "ID"),
 					Tag:   &ast.BasicLit{Kind: token.STRING, Value: fmt.Sprintf("`db:\"%s\" json:\"%s\"`", col.Name, col.Name)},
 				})
@@ -52,7 +60,7 @@ func GenerateModelAST(table schema.Table) *ast.GenDecl {
 					} else if strings.HasSuffix(col.Name, "_at") {
 						typeName = "Timestamp"
 					} else {
-						typeName = "int64"
+						typeName = "int"
 					}
 				case "text":
 					typeName = "string"
@@ -102,33 +110,227 @@ func GenerateSaveItemFunc(tbl schema.Table) *ast.FuncDecl {
 		updatePairs = append(updatePairs, col.Name+"="+val)
 	}
 
+	hasFks := false
+	checkForeignKeyFailuresAssignment := &ast.AssignStmt{
+		Lhs: []ast.Expr{ast.NewIdent("checkForeignKeyFailures")},
+		Tok: token.DEFINE,
+		Rhs: []ast.Expr{
+			&ast.FuncLit{
+				Type: &ast.FuncType{
+					Params: &ast.FieldList{
+						List: []*ast.Field{{
+							Names: []*ast.Ident{ast.NewIdent("err")},
+							Type:  ast.NewIdent("error"),
+						}},
+					},
+					Results: &ast.FieldList{
+						List: []*ast.Field{{Type: ast.NewIdent("error")}},
+					},
+				},
+				Body: &ast.BlockStmt{
+					List: func() []ast.Stmt {
+						ret := []ast.Stmt{}
+						// if !isSqliteFkError(err) { return nil }
+						ret = append(ret, &ast.IfStmt{
+							Cond: &ast.UnaryExpr{Op: token.NOT, X: &ast.CallExpr{Fun: ast.NewIdent("IsSqliteFkError"), Args: []ast.Expr{ast.NewIdent("err")}}},
+							Body: &ast.BlockStmt{List: []ast.Stmt{&ast.ReturnStmt{Results: []ast.Expr{ast.NewIdent("nil")}}}},
+						})
+
+						for _, col := range tbl.Columns {
+							if !col.IsForeignKey { // Check both "real" foreign keys and code table values
+								continue
+							}
+							hasFks = true
+
+							structFieldName := fkFieldName(col)
+							structField := &ast.SelectorExpr{X: ast.NewIdent(tbl.VarName), Sel: ast.NewIdent(structFieldName)}
+
+							if col.IsNonCodeTableForeignKey() {
+								// Real foreign key; look up referent by ID to see if it exists
+								ret = append(ret, &ast.IfStmt{
+									Init: &ast.AssignStmt{
+										Lhs: []ast.Expr{ast.NewIdent("_"), ast.NewIdent("err")},
+										Tok: token.DEFINE,
+										Rhs: []ast.Expr{
+											&ast.CallExpr{
+												Fun: &ast.SelectorExpr{X: ast.NewIdent("db"), Sel: ast.NewIdent(getByIDFuncName(col.ForeignKeyTargetTable))},
+												Args: []ast.Expr{
+													structField,
+												},
+											},
+										},
+									},
+									Cond: &ast.CallExpr{
+										Fun: &ast.SelectorExpr{X: ast.NewIdent("errors"), Sel: ast.NewIdent("Is")},
+										Args: []ast.Expr{
+											ast.NewIdent("err"),
+											ast.NewIdent("ErrNotInDB"),
+										},
+									},
+									Body: &ast.BlockStmt{
+										List: []ast.Stmt{
+											&ast.ReturnStmt{
+												Results: []ast.Expr{
+													&ast.CallExpr{
+														Fun: ast.NewIdent("NewForeignKeyError"),
+														Args: []ast.Expr{
+															&ast.BasicLit{Kind: token.STRING, Value: fmt.Sprintf("%q", structFieldName)},
+															&ast.BasicLit{Kind: token.STRING, Value: fmt.Sprintf("%q", col.ForeignKeyTargetTable)},
+															structField,
+														},
+													},
+												},
+											},
+										},
+									},
+								})
+							} else {
+								// Code table value.  Query the table to see if it exists
+								ret = append(ret, &ast.IfStmt{
+									Init: &ast.AssignStmt{
+										Lhs: []ast.Expr{
+											ast.NewIdent("err"),
+										},
+										Tok: token.ASSIGN,
+										Rhs: []ast.Expr{
+											&ast.CallExpr{
+												Fun: &ast.SelectorExpr{X: &ast.SelectorExpr{X: ast.NewIdent("db"), Sel: ast.NewIdent("DB")}, Sel: ast.NewIdent("Get")},
+												Args: []ast.Expr{
+													&ast.CallExpr{Fun: ast.NewIdent("new"), Args: []ast.Expr{ast.NewIdent("int")}},
+													&ast.BasicLit{Kind: token.STRING, Value: fmt.Sprintf("`select 1 from %s where rowid = ?`", col.ForeignKeyTargetTable)},
+													structField,
+												},
+											},
+										},
+									},
+									Cond: &ast.CallExpr{
+										Fun:  &ast.SelectorExpr{X: ast.NewIdent("errors"), Sel: ast.NewIdent("Is")},
+										Args: []ast.Expr{ast.NewIdent("err"), &ast.SelectorExpr{X: ast.NewIdent("sql"), Sel: ast.NewIdent("ErrNoRows")}},
+									},
+									Body: &ast.BlockStmt{
+										List: []ast.Stmt{
+											&ast.ReturnStmt{
+												Results: []ast.Expr{
+													&ast.CallExpr{
+														Fun: ast.NewIdent("NewForeignKeyError"),
+														Args: []ast.Expr{
+															ast.NewIdent(`"Type"`),
+															ast.NewIdent(fmt.Sprintf("%q", col.ForeignKeyTargetTable)),
+															structField,
+														},
+													},
+												},
+											},
+										},
+									},
+								})
+							}
+						}
+						// final return nil
+						ret = append(ret, &ast.ReturnStmt{Results: []ast.Expr{ast.NewIdent("nil")}})
+						return ret
+					}(),
+				},
+			},
+		},
+	}
+
 	insertStmt := fmt.Sprintf("\n\t\t    insert into %s (%s)\n\t\t         values (%s)\n\t\t", tbl.TableName, strings.Join(insertCols, ", "), strings.Join(insertVals, ", "))
 	updateStmt := fmt.Sprintf("\n\t\t    update %s\n\t\t       set %s\n\t\t     where rowid = :rowid\n\t\t", tbl.TableName, strings.Join(updatePairs, ",\n\t\t           "))
 
 	funcBody := &ast.BlockStmt{
-		List: []ast.Stmt{
-			&ast.IfStmt{
+		List: func() []ast.Stmt {
+			ret := []ast.Stmt{}
+			if hasFks {
+				ret = append(ret, checkForeignKeyFailuresAssignment)
+			}
+			// if item.ID == 0 {...} else {...}
+			ret = append(ret, &ast.IfStmt{
 				Cond: &ast.BinaryExpr{
 					X:  &ast.SelectorExpr{X: ast.NewIdent(tbl.VarName), Sel: ast.NewIdent("ID")},
 					Op: token.EQL,
 					Y:  &ast.BasicLit{Kind: token.INT, Value: "0"},
 				},
 				Body: &ast.BlockStmt{
-					List: []ast.Stmt{
-						&ast.AssignStmt{
-							Lhs: []ast.Expr{ast.NewIdent("result")},
-							Tok: token.DEFINE,
-							Rhs: []ast.Expr{&ast.CallExpr{
-								Fun: ast.NewIdent("Must"),
-								Args: []ast.Expr{&ast.CallExpr{
+					// Do create
+					List: append(
+						func() []ast.Stmt {
+							namedExecStmt := &ast.CallExpr{
 								Fun: &ast.SelectorExpr{X: ast.NewIdent("db.DB"), Sel: ast.NewIdent("NamedExec")},
 								Args: []ast.Expr{
 									&ast.BasicLit{Kind: token.STRING, Value: "`" + insertStmt + "`"},
 									ast.NewIdent(tbl.VarName),
 								},
-								}},
+							}
+							if !hasFks {
+								// No foreign key checking needed; just use `Must` for brevity
+								return []ast.Stmt{
+									&ast.AssignStmt{
+										Lhs: []ast.Expr{ast.NewIdent("result")},
+										Tok: token.DEFINE,
+										Rhs: []ast.Expr{&ast.CallExpr{
+											Fun:  ast.NewIdent("Must"),
+											Args: []ast.Expr{namedExecStmt},
 										}},
 									},
+								}
+							}
+
+							return []ast.Stmt{
+								// result, err := db.DB.NamedExec(`...`, u)
+								&ast.AssignStmt{
+									Lhs: []ast.Expr{
+										ast.NewIdent("result"),
+										ast.NewIdent("err"),
+									},
+									Tok: token.DEFINE,
+									Rhs: []ast.Expr{namedExecStmt},
+								},
+
+								// if fkErr := checkForeignKeyFailures(err); fkErr != nil { return fkErr } else if err != nil { panic(err) }
+								&ast.IfStmt{
+									Init: &ast.AssignStmt{
+										Lhs: []ast.Expr{ast.NewIdent("fkErr")},
+										Tok: token.DEFINE,
+										Rhs: []ast.Expr{
+											&ast.CallExpr{
+												Fun:  ast.NewIdent("checkForeignKeyFailures"),
+												Args: []ast.Expr{ast.NewIdent("err")},
+											},
+										},
+									},
+									Cond: &ast.BinaryExpr{
+										X:  ast.NewIdent("fkErr"),
+										Op: token.NEQ,
+										Y:  ast.NewIdent("nil"),
+									},
+									Body: &ast.BlockStmt{
+										List: []ast.Stmt{
+											&ast.ReturnStmt{
+												Results: []ast.Expr{ast.NewIdent("fkErr")},
+											},
+										},
+									},
+									Else: &ast.IfStmt{
+										Cond: &ast.BinaryExpr{
+											X:  ast.NewIdent("err"),
+											Op: token.NEQ,
+											Y:  ast.NewIdent("nil"),
+										},
+										Body: &ast.BlockStmt{
+											List: []ast.Stmt{
+												&ast.ExprStmt{
+													X: &ast.CallExpr{
+														Fun:  ast.NewIdent("panic"),
+														Args: []ast.Expr{ast.NewIdent("err")},
+													},
+												},
+											},
+										},
+									},
+								},
+							}
+						}(),
 						&ast.AssignStmt{
 							Lhs: []ast.Expr{&ast.SelectorExpr{X: ast.NewIdent(tbl.VarName), Sel: ast.NewIdent("ID")}},
 							Tok: token.ASSIGN,
@@ -143,9 +345,10 @@ func GenerateSaveItemFunc(tbl schema.Table) *ast.FuncDecl {
 								}},
 							}},
 						},
-					},
+					),
 				},
 				Else: &ast.BlockStmt{
+					// Do update
 					List: []ast.Stmt{
 						&ast.AssignStmt{
 							Lhs: []ast.Expr{ast.NewIdent("result")},
@@ -175,8 +378,13 @@ func GenerateSaveItemFunc(tbl schema.Table) *ast.FuncDecl {
 						},
 					},
 				},
-			},
-		},
+			})
+			if hasFks {
+				// If there's foreign key checking, it needs to return an error (or nil)
+				ret = append(ret, &ast.ReturnStmt{Results: []ast.Expr{ast.NewIdent("nil")}})
+			}
+			return ret
+		}(),
 	}
 
 	funcDecl := &ast.FuncDecl{
@@ -184,18 +392,25 @@ func GenerateSaveItemFunc(tbl schema.Table) *ast.FuncDecl {
 		Name: ast.NewIdent("Save" + tbl.GoTypeName),
 		Type: &ast.FuncType{
 			Params: &ast.FieldList{List: []*ast.Field{{Names: []*ast.Ident{ast.NewIdent(tbl.VarName)}, Type: &ast.StarExpr{X: ast.NewIdent(tbl.GoTypeName)}}}},
-			Results: nil,
+			Results: func() *ast.FieldList {
+				if hasFks {
+					return &ast.FieldList{List: []*ast.Field{{Type: ast.NewIdent("error")}}}
+				}
+				return nil
+			}(),
 		},
 		Body: funcBody,
 	}
 	return funcDecl
 }
 
+func getByIDFuncName(tblname string) string {
+	return "Get" + schema.TypenameFromTablename(tblname) + "ByID"
+}
+
 // GenerateGetItemByIDFunc produces an AST for the `GetXyzByID()` function.
 // E.g., a table with `table.TypeName = "foods"` will produce a "GetFoodByID()" function.
 func GenerateGetItemByIDFunc(tbl schema.Table) *ast.FuncDecl {
-	funcName := "Get" + tbl.GoTypeName + "ByID"
-
 	recv := &ast.FieldList{List: []*ast.Field{{Names: []*ast.Ident{ast.NewIdent("db")}, Type: ast.NewIdent("DB")}}}
 	arg := &ast.FieldList{List: []*ast.Field{{Names: []*ast.Ident{ast.NewIdent("id")}, Type: ast.NewIdent(tbl.TypeIDName)}}}
 	result := &ast.FieldList{List: []*ast.Field{{Names: []*ast.Ident{ast.NewIdent("ret")}, Type: ast.NewIdent(tbl.GoTypeName)}, {Names: []*ast.Ident{ast.NewIdent("err")}, Type: ast.NewIdent("error")}}}
@@ -228,7 +443,7 @@ func GenerateGetItemByIDFunc(tbl schema.Table) *ast.FuncDecl {
 
 	funcDecl := &ast.FuncDecl{
 		Recv: recv,
-		Name: ast.NewIdent(funcName),
+		Name: ast.NewIdent(getByIDFuncName(tbl.TableName)),
 		Type: &ast.FuncType{Params: arg, Results: result},
 		Body: funcBody,
 	}
@@ -258,12 +473,12 @@ func GenerateGetAllItemsFunc(tbl schema.Table) *ast.FuncDecl {
 					&ast.UnaryExpr{Op: token.AND, X: ast.NewIdent("ret")},
 					&ast.BinaryExpr{
 						X: &ast.BinaryExpr{
-							X:  &ast.BasicLit{Kind: token.STRING, Value: "`SELECT `"},
+							X:  &ast.BasicLit{Kind: token.STRING, Value: "`select `"},
 							Op: token.ADD,
 							Y:  SQLFieldsConstIdent(tbl),
 						},
 						Op: token.ADD,
-						Y:  &ast.BasicLit{Kind: token.STRING, Value: "` FROM " + tbl.TableName + "`"},
+						Y:  &ast.BasicLit{Kind: token.STRING, Value: "` from " + tbl.TableName + "`"},
 					},
 				},
 			},
@@ -351,8 +566,12 @@ func GenerateDeleteItemFunc(tbl schema.Table) *ast.FuncDecl {
 func GenerateSQLFieldsConst(tbl schema.Table) *ast.GenDecl {
 	columns := make([]string, 0, len(tbl.Columns))
 	for _, col := range tbl.Columns {
+		if col.IsNullableForeignKey() {
+			columns = append(columns, fmt.Sprintf("ifnull(%s, 0) %s", col.Name, col.Name))
+		} else {
 			columns = append(columns, col.Name)
 		}
+	}
 	// Join with comma and space
 	value := "`" + strings.Join(columns, ", ") + "`"
 

pkg/schema/table.go

@@ -1,5 +1,7 @@
 package schema
 
+import "strings"
+
 // Column represents a single column in a table.
 type Column struct {
 	TableName              string `db:"table_name"`
@@ -20,6 +22,10 @@ func (c Column) IsNullableForeignKey() bool {
 	return !c.IsNotNull && !c.IsPrimaryKey && c.IsForeignKey
 }
 
+func (c Column) IsNonCodeTableForeignKey() bool {
+	return c.IsForeignKey && strings.HasSuffix(c.Name, "_id")
+}
+
 // Table is a single SQLite table.
 type Table struct {
 	TableName string `db:"name"`