mgs-graphql/lib/utils/Connection.js

The simple way to generates GraphQL schemas and Sequelize models from your models definition,microservice supported

'use strict'
const _ = require('lodash')

const resolve = async function connectionResolve (Model, {args = {}, condition = {}, include = [], sort = [], sequelizeOptions = {}}) {
  let {after, first, before, last} = args
  first = (first == null ? 100 : first)

  const count = await Model.count({
    where: condition,
    include,
    distinct: true,
    col: sequelizeOptions.group ? sequelizeOptions.group : 'id'
  })
  if (last || before) {
    throw new Error('Argument last or before is not supported!')
  }
  const offset = Math.max(after != null ? parseInt(after) : 0, 0)

  sort = sort || args.sort || []

  let order = sort.map(({field, order}) => [field, order])

  const result = await Model.findAll({
    where: condition,
    include,
    limit: first,
    offset: offset,
    order,
    ...sequelizeOptions
  })

  let index = 0
  let startCursor = offset + 1
  let endCursor = offset + result.length
  return {
    pageInfo: {
      startCursor: startCursor,
      endCursor: endCursor,
      hasPreviousPage: offset > 0,
      hasNextPage: offset + result.length < count
    },
    edges: result.map(node => {
      return {
        node: node,
        cursor: offset + (++index)
      }
    }),
    count: count
  }
}

const sqlResolve = async function (sequelize, modelName, args) {
  let {after, first, before, last, conditionSql, orderBySql, replacements} = args

  first = (first == null ? 100 : first)

  const count = (await sequelize.query('select count(*) as count ' + conditionSql, {replacements: replacements}))[0][0].count

  if (last || before) {
    throw new Error('Argument last or before is not supported!')
  }

  const offset = Math.max(after != null ? parseInt(after) : 0, 0)

  const tableName = sequelize.models[modelName].options.tableName || sequelize.models[modelName].options.name.plural

  const columnMappings = []
  _.forOwn(sequelize.models[modelName].tableAttributes, (field, key) => {
    if (field && field.field && field.fieldName) {
      if (field.field === field.fieldName) {
        columnMappings.push(`${tableName}.${field.field}`)
      } else {
        columnMappings.push(`${tableName}.${field.field} as ${field.fieldName}`)
      }
    }
  })

  const result = await sequelize.query(`select ${columnMappings.join(', ')} ${conditionSql} ${orderBySql} LIMIT ${first} OFFSET ${offset}`
    , {
      replacements: replacements,
      model: sequelize.models[modelName],
      mapToModel: true
    }
  )

  let index = 0
  let startCursor = offset + 1
  let endCursor = offset + result.length
  return {
    pageInfo: {
      startCursor: startCursor,
      endCursor: endCursor,
      hasPreviousPage: offset > 0,
      hasNextPage: offset + result.length < count
    },
    edges: result.map(node => {
      return {
        node: node,
        cursor: offset + (++index)
      }
    }),
    count: count
  }
}

module.exports = {
  resolve,
  sqlResolve
}