我第一次尝试进行ORM Sequelize，遇到一个我不知道如何解决的问题，希望您能为我提供帮助。我正在定义一些模型，但是当我尝试定义一个EmiratesTo关联时，会引发异常：
throw new Error(this.name + '.' + Utils.lowercaseFirst(Type.toString()) + ' called with something that\'s not a subclass of Sequelize.Model');
^
Error: reference.class BelongsTo extends Association {
constructor(source, target, options) {
super(source, target, options);
this.associationType = 'BelongsTo';
this.isSingleAssociation = true;
this.foreignKeyAttribute = {};
if (this.as) {
this.isAliased = true;
this.options.name = {
singular: this.as
};
} else {
this.as = this.target.options.name.singular;
this.options.name = this.target.options.name;
}
if (_.isObject(this.options.foreignKey)) {
this.foreignKeyAttribute = this.options.foreignKey;
this.foreignKey = this.foreignKeyAttribute.name || this.foreignKeyAttribute.fieldName;
} else if (this.options.foreignKey) {
this.foreignKey = this.options.foreignKey;
}
if (!this.foreignKey) {
this.foreignKey = Utils.camelizeIf(
[
Utils.underscoredIf(this.as, this.source.options.underscored),
this.target.primaryKeyAttribute
].join('_'),
!this.source.options.underscored
);
}
this.identifier = this.foreignKey;
if (this.source.rawAttributes[this.identifier]) {
this.identifierField = this.source.rawAttributes[this.identifier].field || this.identifier;
}
this.targetKey = this.options.targetKey || this.target.primaryKeyAttribute;
this.targetKeyField = this.target.rawAttributes[this.targetKey].field || this.targetKey;
this.targetKeyIsPrimary = this.targetKey === this.target.primaryKeyAttribute;
this.targetIdentifier = this.targetKey;
this.associationAccessor = this.as;
this.options.useHooks = options.useHooks;
// Get singular name, trying to uppercase the first letter, unless the model forbids it
const singular = Utils.uppercaseFirst(this.options.name.singular);
this.accessors = {
get: 'get' + singular,
set: 'set' + singular,
create: 'create' + singular
};
}
// the id is in the source table
injectAttributes() {
const newAttributes = {};
newAttributes[this.foreignKey] = _.defaults({}, this.foreignKeyAttribute, {
type: this.options.keyType || this.target.rawAttributes[this.targetKey].type,
allowNull: true
});
if (this.options.constraints !== false) {
const source = this.source.rawAttributes[this.foreignKey] || newAttributes[this.foreignKey];
this.options.onDelete = this.options.onDelete || (source.allowNull ? 'SET NULL' : 'NO ACTION');
this.options.onUpdate = this.options.onUpdate || 'CASCADE';
}
Helpers.addForeignKeyConstraints(newAttributes[this.foreignKey], this.target, this.source, this.options, this.targetKeyField);
Utils.mergeDefaults(this.source.rawAttributes, newAttributes);
this.identifierField = this.source.rawAttributes[this.foreignKey].field || this.foreignKey;
this.source.refreshAttributes();
Helpers.checkNamingCollision(this);
return this;
}
mixin(obj) {
const methods = ['get', 'set', 'create'];
Helpers.mixinMethods(this, obj, methods);
}
/**
* Get the associated instance.
*
* @param {Object} [options]
* @param {String|Boolean} [options.scope] Apply a scope on the related model, or remove its default scope by passing false.
* @param {String} [options.schema] Apply a schema on the related model
* @see {@link Model.findOne} for a full explanation of options
* @return {Promise<Model>}
*/
get(instances, options) {
const association = this;
const where = {};
let Target = association.target;
let instance;
options = Utils.cloneDeep(options);
if (options.hasOwnProperty('scope')) {
if (!options.scope) {
Target = Target.unscoped();
} else {
Target = Target.scope(options.scope);
}
}
if (options.hasOwnProperty('schema')) {
Target = Target.schema(options.schema, options.schemaDelimiter);
}
if (!Array.isArray(instances)) {
instance = instances;
instances = undefined;
}
if (instances) {
where[association.targetKey] = {
[Op.in]: instances.map(instance => instance.get(association.foreignKey))
};
} else {
if (association.targetKeyIsPrimary && !options.where) {
return Target.findById(instance.get(association.foreignKey), options);
} else {
where[association.targetKey] = instance.get(association.foreignKey);
options.limit = null;
}
}
options.where = options.where ?
{[Op.and]: [where, options.where]} :
where;
if (instances) {
return Target.findAll(options).then(results => {
const result = {};
for (const instance of instances) {
result[instance.get(association.foreignKey, {raw: true})] = null;
}
for (const instance of results) {
result[instance.get(association.targetKey, {raw: true})] = instance;
}
return result;
});
}
return Target.findOne(options);
}
/**
* Set the associated model.
*
* @param {Model|String|Number} [newAssociation] An persisted instance or the primary key of an instance to associate with this. Pass `null` or `undefined` to remove the association.
* @param {Object} [options] Options passed to `this.save`
* @param {Boolean} [options.save=true] Skip saving this after setting the foreign key if false.
* @return {Promise}
*/
set(sourceInstance, associatedInstance, options) {
const association = this;
options = options || {};
let value = associatedInstance;
if (associatedInstance instanceof association.target) {
value = associatedInstance[association.targetKey];
}
sourceInstance.set(association.foreignKey, value);
if (options.save === false) return;
options = _.extend({
fields: [association.foreignKey],
allowNull: [association.foreignKey],
association: true
}, options);
// passes the changed field to save, so only that field get updated.
return sourceInstance.save(options);
}
/**
* Create a new instance of the associated model and associate it with this.
*
* @param {Object} [values]
* @param {Object} [options] Options passed to `target.create` and setAssociation.
* @see {@link Model#create} for a full explanation of options
* @return {Promise}
*/
create(sourceInstance, values, fieldsOrOptions) {
const association = this;
const options = {};
if ((fieldsOrOptions || {}).transaction instanceof Transaction) {
options.transaction = fieldsOrOptions.transaction;
}
options.logging = (fieldsOrOptions || {}).logging;
return association.target.create(values, fieldsOrOptions).then(newAssociatedObject =>
sourceInstance[association.accessors.set](newAssociatedObject, options)
);
}
} called with something that's not a subclass of Sequelize.Model
at Function.<anonymous> (/home/wolgan/TCC2/web/node_modules/sequelize/lib/associations/mixin.js:81:13)
at Object.<anonymous> (/home/wolgan/TCC2/web/models/Reference.js:11:11)
at Module._compile (module.js:660:30)
at Object.Module._extensions..js (module.js:671:10)
at Module.load (module.js:573:32)
at tryModuleLoad (module.js:513:12)
at Function.Module._load (module.js:505:3)
at Module.require (module.js:604:17)
at require (internal/module.js:11:18)
at Object.<anonymous> (/home/wolgan/TCC2/web/models/Project.js:4:19)
at Module._compile (module.js:660:30)
at Object.Module._extensions..js (module.js:671:10)
at Module.load (module.js:573:32)
at tryModuleLoad (module.js:513:12)
at Function.Module._load (module.js:505:3)
at Module.require (module.js:604:17)
at require (internal/module.js:11:18)
at Object.<anonymous> (/home/wolgan/TCC2/web/models/Researcher.js:4:17)
at Module._compile (module.js:660:30)
at Object.Module._extensions..js (module.js:671:10)
at Module.load (module.js:573:32)
at tryModuleLoad (module.js:513:12)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! web@0.0.0 start: `PORT=8000 node ./bin/www`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the web@0.0.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
npm ERR! A complete log of this run can be found in:
npm ERR! /home/wolgan/.npm/_logs/2018-10-02T17_26_00_132Z-debug.log
使用一些“ console.log调试”，我看到当执行到达这里的belongsTo时会发生异常：
const Researcher = require('./Researcher');
const Project = sequelize.define('projects', {
sippee_id: {
type: Sequelize.INTEGER,
},
});
console.log(2)
Project.belongsTo(Researcher);
答案 0 :(得分：0)
此错误的最可能原因是，您已经在“ Researcher”定义文件中包括了“ Project”模型，并在那里声明了关联。 有几种方法可以解决此问题。
我的首选方法不是在单个文件中声明关联，而是为此目的专门使用另一个文件。从那里导出所有模型。并且每当您需要使用模型时，都应包含用于关联的文件。示例：
const Researcher = require('./Researcher');
const Project = require('./Project');
Project.belongsTo(Researcher);
Researcher.hasMany(Project);
module.exports = {Researcher:Researcher,Project:Project};
//association.js
在您的app.js或其他文件中：
const db = require('./db/association.js');
const Researcher = db.Researcher;
const Project = db.Project;
Project.findAll().then(projects => {
//Your code
})
您还可以看一下Sequelize官方github页面上给出的以下示例： Sequelize Express example