postgresql - 需要自定义 Sequelize Postgres 数据类型的工作示例
问题描述
我在 Postgres 中有一个自定义类型,我想在 Sequelize 中使用它。我已经根据 Sequelize 文档中的示例编写了代码,除了调用我在 Sequelize 或其他地方找不到的函数(“继承”)。但是,使用 sequelize.define 创建具有此自定义类型属性的模型会在 Sequelize 中引发异常。我的代码中是否有突出的错误?还是有另一个很好的例子或教程来实现自定义数据类型?此外,文档示例中显示的“继承”功能是怎么回事——文档是否遗漏了导入/要求,或者该调用是否错误?
我关注的文档在这里:http ://docs.sequelizejs.com/manual/data-types.html#extending-datatypes
Postgres 中定义的类型:
CREATE TYPE public.measurement AS
(
unit text,
value double precision
);
我在 NodeJS 中的测试代码:
const Sequelize = require('sequelize');
let dataTypes = Sequelize.DataTypes;
// Create class for custom datatype
class MEASUREMENT extends dataTypes.ABSTRACT {
toSql() {
console.log('MEASUREMENT toSql');
return 'MEASUREMENT';
}
static parse(value) {
console.log('MEASUREMENT parse value=', value);
return value;
}
};
// Set key
MEASUREMENT.prototype.key = 'MEASUREMENT';
MEASUREMENT.key = MEASUREMENT.prototype.key;
// Add to DataTypes
dataTypes.MEASUREMENT = MEASUREMENT;
// Add to Sequelize
Sequelize.MEASUREMENT = Sequelize.Utils.classToInvokable(MEASUREMENT);
let pgTypes = dataTypes.postgres;
// Map dialects
dataTypes.MEASUREMENT.types.postgres = ['MEASUREMENT']
pgTypes.MEASUREMENT = function MEASUREMENT() {
if (!(this instanceof pgTypes.MEASUREMENT)) return new pgTypes.MEASUREMENT();
DataTypes.MEASUREMENT.apply(this, arguments);
}
// inherits(pgTypes.MEASUREMENT, dataTypes.MEASUREMENT);
// Node throws a parse error. This is in the example in the Sequelize docs, however.
pgTypes.MEASUREMENT.parse = dataTypes.MEASUREMENT.parse;
// ------------------------------
const sequelize = new Sequelize('test', 'test', 'test', {
host: 'localhost',
dialect: 'postgres'
});
const Thing = sequelize.define('thing', {
name: Sequelize.STRING,
weight: Sequelize.MEASUREMENT
});
运行时调用堆栈:
C:\Workspaces\nebula\server\node_modules\sequelize\lib\dialects\abstract\connection-manager.js:48
if (dataType.types[this.dialectName]) {
^
TypeError: Cannot read property 'postgres' of undefined
at _.each.dataType (C:\Workspaces\nebula\server\node_modules\sequelize\lib\dialects\abstract\connection-manager.js:48:27)
at C:\Workspaces\nebula\server\node_modules\lodash\lodash.js:4911:15
at baseForOwn (C:\Workspaces\nebula\server\node_modules\lodash\lodash.js:2996:24)
at C:\Workspaces\nebula\server\node_modules\lodash\lodash.js:4880:18
at Function.forEach (C:\Workspaces\nebula\server\node_modules\lodash\lodash.js:9344:14)
at ConnectionManager.refreshTypeParser (C:\Workspaces\nebula\server\node_modules\sequelize\lib\dialects\abstract\connection-manager.js:46:7)
at new ConnectionManager (C:\Workspaces\nebula\server\node_modules\sequelize\lib\dialects\postgres\connection-manager.js:23:10)
at new PostgresDialect (C:\Workspaces\nebula\server\node_modules\sequelize\lib\dialects\postgres\index.js:14:30)
at new Sequelize (C:\Workspaces\nebula\server\node_modules\sequelize\lib\sequelize.js:320:20)
at Object.<anonymous> (C:\Workspaces\nebula\server\testsequelizecustom.js:58:19)
at Module._compile (internal/modules/cjs/loader.js:689:30)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:700:10)
at Module.load (internal/modules/cjs/loader.js:599:32)
at tryModuleLoad (internal/modules/cjs/loader.js:538:12)
at Function.Module._load (internal/modules/cjs/loader.js:530:3)
at Function.Module.runMain (internal/modules/cjs/loader.js:742:12)
at startup (internal/bootstrap/node.js:279:19)
at bootstrapNodeJSCore (internal/bootstrap/node.js:752:3)
解决方案
要修复错误,我们需要定义postgres
对象上的属性。dataType.types
就在您已经拥有的那一行之下:
pgTypes.MEASUREMENT.parse = dataTypes.MEASUREMENT.parse;
添加以下行,错误应该消失:
pgTypes.MEASUREMENT.types = {postgres:[‘MEASUREMENT’]};
您可能还需要添加这一行,以处理相关错误(见下文)。
dataTypes.postgres.MEASUREMENT.key = ‘MEASUREMENT’;
相关错误:
[...]/node_modules/sequelize/lib/dialects/postgres/connection-manager.js:36
if (dataType.key.toLowerCase() === 'range') {
^
TypeError: Cannot read property 'toLowerCase' of undefined
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