firestore查询中的条件where子句 [英] Conditional where clause in firestore queries

问题描述

我从firestore获取了一些数据但在我的查询中我想添加一个条件where子句。我正在使用async-await for api而不确定如何添加consitional where子句。

I have fetch some data from firestore but in my query I want to add a conditional where clause. I am using async-await for api and not sure how to add a consitional where clause.

这是我的函数

export async function getMyPosts (type) {
  await api
  var myPosts = []

  const posts = await api.firestore().collection('posts').where('status', '==', 'published')
    .get()
    .then(snapshot => {
      snapshot.forEach(doc => {
        console.log(doc.data())
      })
    })
    .catch(catchError)
}

在我的主要功能中，我得到一个名为'type'的参数。根据该参数的值，我想在上面的查询中添加另一个qhere子句。例如，如果type ='nocomments'，那么我想添加一个where子句。 where（'commentCount'，'=='，0 ），否则如果type ='nocategories'，那么where子句将查询另一个属性，如 .where（' tags'，'=='，'none'）

In my main function I am getting a param called 'type'. Based on the value of that param I want to add another qhere clause to the above query. For example, if type = 'nocomments', then I want to add a where clause .where('commentCount', '==', 0), otherwise if type = 'nocategories', then the where clause will be querying another property like .where('tags', '==', 'none')

我无法理解如何添加此条件where子句。

I am unable to understand how to add this conditional where clause.

注意：在firestore中添加多个条件，只需附加where子句，如 - 。 where（state，==，CA） .where（population，>，1000000）依此类推。

NOTE: in firestore you add multiple conditions by just appending your where clauses like - .where("state", "==", "CA").where("population", ">", 1000000) and so on.

推荐答案

仅在需要时将where子句添加到查询中：

Add the where clause to the query only when needed:

export async function getMyPosts (type) {
  await api
  var myPosts = []

  var query = api.firestore().collection('posts')
  if (your_condition_is_true) {  // you decide
    query = query.where('status', '==', 'published')
  }
  const questions = await query.get()
    .then(snapshot => {
      snapshot.forEach(doc => {
        console.log(doc.data())
      })
    })
    .catch(catchError)
}

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