Feat custom typecast

__tests__/decode.test.ts

@@ -0,0 +1,32 @@
+import type { Field } from '../src'
+import { ColumnType, Decoders } from '../src/config'
+import { cast } from '../src/decode'
+
+describe('decode', () => {
+  describe('cast', () => {
+    test('use default decode method if config not provided', () => {
+      expect(cast(makeField(ColumnType.BIGINT), '21412421321421521321', {})).toEqual('21412421321421521321')
+      expect(cast(makeField(ColumnType.FLOAT), '1.2', {})).toEqual(1.2)
+      expect(cast(makeField(ColumnType.INT), '1', {})).toEqual(1)
+    })
+
+    test('override default decode method if config provided', () => {
+      const config: Decoders = {
+        [ColumnType.BIGINT]: BigInt,
+        [ColumnType.FLOAT]: String
+      }
+
+      expect(cast(makeField(ColumnType.BIGINT), '21412421321421521321', config)).toEqual(21412421321421521321n)
+      expect(cast(makeField(ColumnType.FLOAT), '1.2', config)).toEqual('1.2')
+      expect(cast(makeField(ColumnType.INT), '1', config)).toEqual(1)
+    })
+  })
+})
+
+function makeField(type: ColumnType): Field {
+  return {
+    name: 'foo',
+    type: type,
+    nullable: false
+  }
+}

src/config.ts

@@ -23,15 +23,55 @@ export interface Config {
   fetch?: (input: string, init?: Req) => Promise<Res>
   arrayMode?: boolean
   fullResult?: boolean
+  decoders?: Decoders
 }
 
 export interface ExecuteOptions {
   arrayMode?: boolean
   fullResult?: boolean
+  decoders?: Decoders
 }
 
 export interface TxOptions {
   isolation?: 'READ COMMITTED' | 'REPEATABLE READ'
 }
 
 export type ExecuteArgs = object | any[] | null
+
+export const enum ColumnType {
+  TINYINT = 'TINYINT',
+  UNSIGNED_TINYINT = 'UNSIGNED TINYINT',
+  SMALLINT = 'SMALLINT',
+  UNSIGNED_SMALLINT = 'UNSIGNED SMALLINT',
+  MEDIUMINT = 'MEDIUMINT',
+  INT = 'INT',
+  UNSIGNED_INT = 'UNSIGNED INT',
+  YEAR = 'YEAR',
+  FLOAT = 'FLOAT',
+  DOUBLE = 'DOUBLE',
+  BIGINT = 'BIGINT',
+  UNSIGNED_BIGINT = 'UNSIGNED BIGINT',
+  DECIMAL = 'DECIMAL',
+  CHAR = 'CHAR',
+  VARCHAR = 'VARCHAR',
+  BINARY = 'BINARY',
+  VARBINARY = 'VARBINARY',
+  TINYTEXT = 'TINYTEXT',
+  TEXT = 'TEXT',
+  MEDIUMTEXT = 'MEDIUMTEXT',
+  LONGTEXT = 'LONGTEXT',
+  TINYBLOB = 'TINYBLOB',
+  BLOB = 'BLOB',
+  MEDIUMBLOB = 'MEDIUMBLOB',
+  LONGBLOB = 'LONGBLOB',
+  DATE = 'DATE',
+  TIME = 'TIME',
+  DATETIME = 'DATETIME',
+  TIMESTAMP = 'TIMESTAMP',
+  BIT = 'BIT',
+  JSON = 'JSON'
+}
+
+export type Decoders = {
+  [P in ColumnType]?: (rawValue: string) => any
+}

src/decode.ts

@@ -1,10 +1,16 @@
+import { Decoders } from './config'
 import { Field } from './index.js'
 
-export function cast(field: Field, value: string | null): any {
+export function cast(field: Field, value: string | null, decoder: Decoders): any {
   if (value === null) {
     return null
   }
 
+  // use user provided decoder if exists
+  if (decoder[field.type]) {
+    return decoder[field.type](value)
+  }
+
   switch (field.type) {
     // bool will be converted to TINYINT
     case 'TINYINT':

src/index.ts

@@ -1,7 +1,7 @@
 import { format } from './format.js'
 import { cast } from './decode.js'
 import { DatabaseError } from './error.js'
-import { Config, ExecuteOptions, ExecuteArgs, TxOptions } from './config.js'
+import { Config, ExecuteOptions, ExecuteArgs, TxOptions, Decoders } from './config.js'
 import { postQuery } from './serverless.js'
 
 export { Config, ExecuteOptions, ExecuteArgs, DatabaseError }
@@ -120,9 +120,10 @@ export class Connection {
 
     const arrayMode = options.arrayMode ?? this.config.arrayMode ?? false
     const fullResult = options.fullResult ?? this.config.arrayMode ?? false
+    const decoders = { ...this.config.decoders, ...options.decoders }
 
     const fields = resp?.types ?? []
-    const rows = resp ? parse(fields, resp?.rows ?? [], cast, arrayMode) : []
+    const rows = resp ? parse(fields, resp?.rows ?? [], cast, arrayMode, decoders) : []
 
     if (fullResult) {
       const rowsAffected = resp?.rowsAffected ?? 0
@@ -147,19 +148,19 @@ export function connect(config: Config): Connection {
 }
 
 type Cast = typeof cast
-function parseArrayRow(fields: Field[], rawRow: string[], cast: Cast): Row {
+function parseArrayRow(fields: Field[], rawRow: string[], cast: Cast, decoders: Decoders): Row {
   return fields.map((field, ix) => {
-    return cast(field, rawRow[ix])
+    return cast(field, rawRow[ix], decoders)
   })
 }
 
-function parseObjectRow(fields: Field[], rawRow: string[], cast: Cast): Row {
+function parseObjectRow(fields: Field[], rawRow: string[], cast: Cast, decoders: Decoders): Row {
   return fields.reduce((acc, field, ix) => {
-    acc[field.name] = cast(field, rawRow[ix])
+    acc[field.name] = cast(field, rawRow[ix], decoders)
     return acc
   }, {} as Row)
 }
 
-function parse(fields: Field[], rows: string[][], cast: Cast, arrayMode: boolean): Row[] {
-  return rows.map((row) => (arrayMode === true ? parseArrayRow(fields, row, cast) : parseObjectRow(fields, row, cast)))
+function parse(fields: Field[], rows: string[][], cast: Cast, arrayMode: boolean, decode: Decoders): Row[] {
+  return rows.map((row) => (arrayMode === true ? parseArrayRow(fields, row, cast, decode) : parseObjectRow(fields, row, cast, decode)))
 }