sequelize_models_to_migration_generator.js

const Sequelize = require('sequelize');
const models = require('./models');
const fs = require('fs');

// delete models.default;

const sequelize = new Sequelize(
    '',
    '',
    '', {
        host: '',
        dialect: 'postgres',
    }
);

for(let model in models) {
    if (!(models[model] instanceof Sequelize.Model)) break;
    let attributes = models[model].attributes;
    for(let column in attributes) {
        delete attributes[column].Model;
        delete attributes[column].fieldName;

        const field = attributes[column].field;
        delete attributes[column].field;
        delete attributes[column].validate;
        for(let property in attributes[column]) {
            if(property.startsWith('_')) {
                delete attributes[column][property];
            }
        }

        if(typeof attributes[column]['type'] !== 'undefined') {

            if(typeof attributes[column]['type']['options'] !== 'undefined' && typeof attributes[column]['type']['options'].toString === 'function') {
                attributes[column]['type']['options'] = attributes[column]['type']['options'].toString(sequelize);
            }

            if(typeof attributes[column]['type'].toString === 'function') {
                attributes[column]['type'] = attributes[column]['type'].toString(sequelize);
            }
            const attribute = Object.assign({}, attributes[column]);
            delete attributes[column];
            attributes[field] = attribute;
        }
    }

    // console.log(attributes)

    let schema = JSON.stringify(attributes, null, 2);
    let tableName = models[model].tableName;
    let indexes = ['\n'];

    if(models[model].options.indexes.length) {

        models[model].options.indexes.forEach((obj) => {

            indexes.push('        .then(() => {');
            indexes.push('            return queryInterface.addIndex(');
            indexes.push(`                '${tableName}',`);
            indexes.push(`                ['${obj.fields.join("','")}']`);

            let opts = {};
            if(obj.name) {
                opts.indexName = obj.name;
            }
            if(obj.unique === true) {
                opts.indicesType = 'UNIQUE';
            }
            if(obj.method === true) {
                opts.indexType = obj.method;
            }
            if(Object.keys(opts).length) {
                indexes.push(`                , ${JSON.stringify(opts)}`)
            }

            indexes.push('            )');
            indexes.push('        })');

        });

    }

    schema = schema.split('\n').map((line) => '      ' + line).join('\n');

    let template = `
module.exports = {
  up(queryInterface, Sequelize) {
    return queryInterface.createTable('${tableName}',
${schema})
    },
    down(queryInterface, Sequelize) {
      return queryInterface.dropTable('${tableName}');
    },
};`

    let d = new Date();

    let filename = [d.getFullYear(), d.getMonth()+1, d.getDate(), d.getHours(), d.getMinutes(), d.getSeconds()]
    .map((num) => num <= 60 && (num + 100).toString().substring(1) || num)
    .join('') + `-${models[model].tableName}`;

    fs.writeFileSync(`./tmp2/${filename}.js`, template);

};