Question

我正在使用Knex和Postgres，NodeJS，Express＆amp;反应。我有一个USERS表，一个USERLIKS和一个FILTERS表。我被困的地方是性别查询。用户可以在他们的过滤器中定义他们正在寻找男性，女性或两者。

如果我使用“.orWhereExists”等其他过滤器，例如第二个过滤器，那么您已经不喜欢/拒绝的用户将被忽略。我的直觉说我应该以某种方式嵌套性别查询行，然后将它们更改为“.orWhereExists”，但我不确定如何。

感谢您的帮助。刚刚开始编写并且喜欢它，但这个问题一直是一个令人头疼的问题

Filters is organized like so 
  table.increments('id')   <-----primary
  table.integer('userid')  <-----foreign
  table.integer('min_age');
  table.integer('max_age');
  table.string('female');
  table.string('male');

app.get('/api/potentials', (req, res) => {
  const cookieid = req.session.id
  console.log("potentials get for id ", cookieid)

    knex('users')
     .select('*')
     .whereNot('users.id', cookieid )
     .whereNotExists(knex.select('*').from('userlikes').whereRaw('userlikes.userid1 = ?', [cookieid]).andWhereRaw('users.id = userlikes.userid2'))
     .whereExists(knex.select('*').from('filters').whereRaw('users.gender = filters.female'))
     .whereExists(knex.select('*').from('filters').whereRaw('users.gender = filters.male'))
     .whereExists(knex.select('*').from('filters').whereRaw('users.age >= filters.min_age'))
     .whereExists(knex.select('*').from('filters').whereRaw('users.age < filters.max_age'))
     .then((result) => {
        console.log("filter result", result)
        res.send(result)
          })
    .catch((err) => {
            console.log("error", err)
          })

Answer 1

Knex功能.buildermodify()适用于您的情况。另见：documentation link。

要使用它，您需要创建一个函数，其目的是有条件地将.where或其他类似的子句添加到您的knex查询中，并且在实际的knex查询中，您使用.buildermodify()

文档中的示例：

var withUserName = function(queryBuilder, foreignKey) {
    queryBuilder.leftJoin('users', foreignKey, 'users.id')
        .select('users.user_name');
};

knex.table('articles')
    .select('title', 'body')
    .modify(withUserName, 'articles_user.id')
    .then(function(article) {
          console.log(article.user_name);
    });

将其应用于您获得性别（和年龄）的需求：

/* NEW FUNCTION TO DO THE SPECIAL FILTERING */
function customFiltering(queryBuilder, inputGender, minAge, maxAge) {

    if (inputGender === gender_is_female) { /* you need to fix this */

        /* THIS LINE IS THE SECRET SAUCE TO CONDITIONALLY UPDATE YOUR QUERY */
        /* queryBuilder.<my additional conditional clauses> */
        queryBuilder.whereExists( knex.select('*').from('filters')
                    .whereRaw('users.gender = filters.female'));
    } else if (inputGender === gender_is_male) {
        queryBuilder.whereExists( knex.select('*').from('filters')
                    .whereRaw('users.gender = filters.male'));
    }

    /* ADD MORE CODE HERE for the ages filter - minAge, maxAge */

};

knex('users')
 .select('*')
 .whereNot('users.id', cookieid )
 .whereNotExists( knex.select('*').from('userlikes').whereRaw('userlikes.userid1 = ?', [cookieid]).andWhereRaw('users.id = userlikes.userid2'))
 .modify(customFiltering, inputGender, minAge, maxAge)
 .then((result) => {
    console.log("filter result", result)
    res.send(result)
  })
 .catch((err) => {
    console.log("error", err)
 })

祝你好运！

Answer 2

我通常对复杂查询构建的做法是在纯SQL中编写它，然后尝试将其转换为knex构造。

据我所知，你正在寻找类似的东西

select
  *
from
  users as u
where
    ...
    and (
      (exists select * from filters as f where f.male = u.gender)
      or (exists select * from filters as f where f.female = u.gender)
    )

用knex语言写成

knex('users as u')
  .where('other conditions')
  .where((b) => {
    b
      .whereExists(knex.select('*').from('filters as f').whereRaw('u.gender = f.female'))
      .orWhereExists(knex.select('*').from('filters as f').whereRaw('u.gender = f.male'))
  })

knex有可能将括号中的where子句分组。在here搜索＆＃34; Grouped Chain＆＃34;

Answer 3

A solution someone offline gave me that worked was to use a "promise" but GaryL's solution above is more inline with what I was looking for. In the event it is helpful to people with similar questions this also worked.

> Blockquote
app.get('/api/potentials', (req, res) => {
  const cookieid = 1//req.session.id
  console.log("potentials get for id ", cookieid)
    Promise.all([
    knex('users')
     .select('filters.min_age','filters.max_age', 'filters.female','filters.male')
     .innerJoin('filters', 'users.id', 'filters.userid')
     .where('users.id',cookieid ),

    knex('users')
    .whereNotExists(knex.select('*').from('userlikes').whereRaw('userlikes.userid1 = ?', [cookieid]).andWhereRaw('users.id = userlikes.userid2'))
      ])

     .then((result) => {
        const[filterCriteria, users] = result
        const [min_age, max_age, female, male] = Object.values(filterCriteria[0])
          res.send(users.filter(user => {
           if((user.age >= min_age) && (user.age <= max_age) && ( (user.gender = female) || (user.gender = male) ||  (user.gender = female) && (user.gender = male) ) ) {
            return user
          }
        }))
      })
    .catch((err) => {
            console.log("error", err)
          })
      })

Knex.js，嵌套“.orWhereExists”进入过滤器字段以包含男性，女性或两者的选项

3 个答案: