codegen: add unique index lookup funcs

pkg/codegen/modelgenerate/generate_model.go

@@ -63,7 +63,7 @@ func GenerateModelAST(table schema.Table) *ast.GenDecl {
 					Tag:   &ast.BasicLit{Kind: token.STRING, Value: fmt.Sprintf("`db:\"%s\" json:\"%s\"`", col.Name, col.Name)},
 				})
 			} else {
-				typeName := col.GoType()
+				typeName := col.GoTypeName()
 				fields = append(fields, &ast.Field{
 					Names: []*ast.Ident{ast.NewIdent(textutils.SnakeToCamel(col.Name))},
 					Type:  ast.NewIdent(typeName),
@@ -457,6 +457,51 @@ func GenerateGetItemByIDFunc(tbl schema.Table) *ast.FuncDecl {
 	return funcDecl
 }
 
+// GenerateGetItemByIDFunc produces an AST for the `GetXyzByID()` function.
+// E.g., a table with `table.TypeName = "foods"` will produce a "GetFoodByID()" function.
+func GenerateGetItemByUniqColFunc(tbl schema.Table, col schema.Column) *ast.FuncDecl {
+	// Use the xyzSQLFields constant in the select query
+	selectExpr := &ast.BinaryExpr{
+		X: &ast.BinaryExpr{
+			X:  &ast.BasicLit{Kind: token.STRING, Value: "`\n\t    select `"},
+			Op: token.ADD,
+			Y:  SQLFieldsConstIdent(tbl),
+		},
+		Op: token.ADD,
+		Y:  &ast.BasicLit{Kind: token.STRING, Value: fmt.Sprintf("`\n\t      from %s\n\t     where %s = ?\n\t`", tbl.TableName, col.Name)},
+	}
+
+	param := ast.NewIdent(col.GoVarName())
+
+	return &ast.FuncDecl{
+		Recv: dbRecv,
+		Name: ast.NewIdent("Get" + schema.TypenameFromTablename(tbl.TableName) + "By" + col.GoFieldName()),
+		Type: &ast.FuncType{
+			Params: &ast.FieldList{List: []*ast.Field{
+				{Names: []*ast.Ident{param}, Type: ast.NewIdent(col.GoTypeName())},
+			}},
+			Results: &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")},
+			}},
+		},
+		Body: &ast.BlockStmt{
+			List: []ast.Stmt{
+				&ast.AssignStmt{
+					Lhs: []ast.Expr{ast.NewIdent("err")},
+					Tok: token.ASSIGN,
+					Rhs: []ast.Expr{&ast.CallExpr{Fun: &ast.SelectorExpr{X: dbDB, Sel: ast.NewIdent("Get")}, Args: []ast.Expr{&ast.UnaryExpr{Op: token.AND, X: ast.NewIdent("ret")}, selectExpr, param}}},
+				},
+				&ast.IfStmt{
+					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.CompositeLit{Type: ast.NewIdent(tbl.GoTypeName)}, ast.NewIdent("ErrNotInDB")}}}},
+				},
+				&ast.ReturnStmt{},
+			},
+		},
+	}
+}
+
 // GenerateGetAllItemsFunc produces an AST for the `GetAllXyzs()` function.
 // E.g., a table with `table.TypeName = "foods"` will produce a "GetAllFoods()" function.
 func GenerateGetAllItemsFunc(tbl schema.Table) *ast.FuncDecl {