QueryTyper

Description

QueryTyper is a tool for Typescript projects that make extensive use of raw SQL queries. It enables type checking between the SQL file that defines a query and the Typescript statement where the query is executed. This catches several common mistakes at compile-time, such as:

• An argument X was added to a query, but the application code was not updated to pass X
• The query expects a non-nullable argument X, but the application code passes a nullable value for X
• The query returns an integer field Y, but the application code treats Y as a string

Query directory structure

QueryTyper supports one or more root directories. A root directory can contain one or more query collection directories. A query collection directory can contain one or more query files. Query files should have the name pattern *.query.sql

E.g. a root directory could be server/queries, a query collection directory could be server/queries/users, and a query file could be server/queries/users/addUsers.query.sql.

Query Annotations

Query files can contain single-line annotations using the syntax -- @annotationName [annotationValue]. Every annotation is a SQL comment, so does not affect the query's behavior.

Available query annotations

@arg argName: argType

Defines a query argument argName of type argType

@return fieldName: fieldType

Defines a query return field fieldName or type fieldType

@extendsArgs dt.ArgType

Imports multiple query arguments from a custom type ArgType

@extendsResults dt.ResultType

Imports multiple query results from a custom type ResultType

@unique

Marks the query as returning zero or one row

Configuration file

The configuration file should be named querytyper.config.json and should be placed in the npm package root directory.

Configuration fields

rootDirs

Defines the paths of the root directories. Paths are specified relative to the npm package root.

queryTemplatePath

Defines the path to the query template, relative to the npm package root.

dataTypesPath

Defines the path to a data types Typescript module, relative to the queries. QueryTyper annotations can use custom types from that module.

exportsFileName

QueryTyper will create an exports file inside each query collection directory. exportsFileName defines the name of the exports file.

helperMapping

QueryTyper will support multiple function to execute sql code. You can adde them as property of this object where property name will be the keyword used in sql header and value will be the name of the function to call.

Example configuration file

{
    "rootDirs": ["server/queries", "tests/queries"],
    "queryTemplatePath": "server/queries/query.ts.template",
    "dataTypesPath": "../../../common/DataTypes",
    "exportsFileName": "index.ts",
    "helperMapping": {
        "default": "buildQuery",
        "unique": "buildQueryWithUniqueResult"
    }
}

Query template

The query template defines how to create a Typescript stub from the extracted QueryTyper annotations. A query template can contain symbols prefixed by @ which will be replaced by values

Query template symbols

@extraImports

@extraImports is replaced with addtional import statements e.g. a custom data types module

@helperFunction

@helperFunction is replaced with buildQuery or buildQueryWithUniqueResult

@argumentFields

@argumentFields is replaced with the argument fields

@extendArg

@extendArg is replaced with an extends statement for the argument type

@resultFields

@resultFields is replaced with the result fields

@extendResult

@extendResult is replaced with an extends statement for the result type

@queryName

@queryName is replaced with the query name

@helperFunction

@helperFunction is replaced with non deafult query execution function

Example query template:

/* tslint:disable */
@extraImports
import { @helperFunction } from '../queryHelper';

export interface Arguments @extendArg {
@argumentFields
}

export interface Result @extendResult {
@resultFields
}

export const @queryName = @helperFunction<Arguments, Result>(__filename);