可选参数和条款 .where [英] Optional parameter and clausule .where

问题描述

我正在使用 angularcli 和 angularfire2，我的应用程序有一个带有可选参数的方法，用于在 firestore 中检索数据.

buildWomen(id: string, sex?: string, age?: string): Observable{this.humanCollec = this.db.collection('human/' + id + '/women', ref => ref.where('sex', '==', sex)//--可以为空.where('年龄', '==', 年龄);//-- 这可以为空返回 this.humamObersArray = this.humanCollec.valueChanges();}

为了简化这个例子，我只显示了 2 个参数，但在实际方法中我有 10 个参数.当最后一个参数为 null

时，有一种检查它或忽略 .where 子句的最佳方法

更新:

...service.ts

<预><代码>...humanCol: AngularFirestoreCollection<Human>;humanObersArray: Observable;...buildHuman(id:string,sex?:string,age?:string,ethnicity?:string,height?:string,weight?:string,religion?:string){//:Observable<Human[]>//this.humanCol =this.db.collection('human/'+id+'/women', ref => {让 retVal = ref 为任何；if (sex != null) { retVal = retVal.where('sex', '==', sex) }if (age != null) { retVal = retVal.where('age', '==', age) }if (ethnicity != null) { retVal = retVal.where('ethnicity', '==',ethnicity) }if (height != null) { retVal = retVal.where('height', '==', height) }if (weight != null) { retVal = retVal.where('weight', '==', weight) }如果(宗教！= null){ retVal = retVal.where('宗教'，'=='，宗教)}返回 retVal；//返回 this.humanObersArray = this.humanCol.valueChanges();});}

解决方案

在工厂内的 ref 上构建，检查参数是否存在:

this.humanCollec = this.db.collection(`human/${id}/women`, ref => {让 retVal = ref 为任何；if (sex != null) { retVal = retVal.where('sex', '==', sex) }if (age != null) { retVal = retVal.where('age', '==', age) }...返回 retVal；});

I'm using angularcli and angularfire2, my app have a method with optional parameter for to retrieve data in firestore.

buildWomen(id: string, sex?: string, age?: string): Observable<Humans[]> {
    this.humanCollec = this.db.collection('human/' + id + '/women', ref => ref
      .where('sex', '==', sex) //--this can be null
      .where('age', '==', age); //--this can be null
    return this.humamObersArray = this.humanCollec.valueChanges();
  }

I'm showing only 2 parameters for simplify this example but in real method I have 10 parameters. There is a the best way for check it or ignore .where clausule when last parameter is null

UPDATE:

...service.ts

...
humanCol: AngularFirestoreCollection<Human>;
humanObersArray: Observable<Human[]>;
...
buildHuman(id: string, sex?: string, age?: string, ethnicity?: string, height?: string, weight?: string, religion?: string){ //: Observable<Human[]>
      //this.humanCol = 

      this.db.collection('human/'+id+'/women', ref => {
      let retVal = ref as any;
      if (sex != null) { retVal = retVal.where('sex', '==', sex) }
      if (age != null) { retVal = retVal.where('age', '==', age) }
      if (ethnicity != null) { retVal = retVal.where('ethnicity', '==', ethnicity) }
      if (height != null) { retVal = retVal.where('height', '==', height) }
      if (weight != null) { retVal = retVal.where('weight', '==', weight) }
      if (religion != null) { retVal = retVal.where('religion', '==', religion) }

      return retVal;
      //return this.humanObersArray = this.humanCol.valueChanges();
    });
  }

解决方案

Build on the ref within the factory, checking for the presence of the parameters:

this.humanCollec = this.db.collection(`human/${id}/women`, ref => {
  let retVal = ref as any;
  if (sex != null) { retVal = retVal.where('sex', '==', sex) }
  if (age != null) { retVal = retVal.where('age', '==', age) }
  ...
  return retVal;
});

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