Question

我正在订阅我的firebase数据库中的列表。我想知道如何使用每个项目属性之一进行过滤/查询？

这是我目前用来取回整个列表的内容：

 return this.af.database.list('items');

Answer 1

您可以这样做来过滤搜索结果

Average.Rating.per.Interval <- data.frame(interval=as.numeric(),
                                    occupation=as.character(), 
                                    average.rating=as.numeric(), 
                                    stringsAsFactors=FALSE) 
##interval number refers to the dataset number (e.g. for 'e.1' it is 1, for 'e.2' it's 2)

Average.Rating.per.Interval <- as.matrix(Average.Rating.per.Interval)

e.1.artist <- e.1[which(e.1[,"occupation"]=='artist', arr.ind = TRUE),]
mean(e.1.artist$rating)
Average.Rating.per.Interval <- rbind(Average.Rating.per.Interval, 
c(interval=1,occupation="artist",average.rating=mean(e.1.artist$rating)))


e.1.technician <- e.1[which(e.1[,"occupation"]=='technician', arr.ind = TRUE),]
mean(e.1.technician$rating)
Average.Rating.per.Interval <- rbind(Average.Rating.per.Interval, 
c(1,"technician",mean(e.1.technician$rating)))


e.1.marketing <- e.1[which(e.1[,"occupation"]=='marketing', arr.ind = TRUE),]
mean(e.1.marketing$rating)
Average.Rating.per.Interval <- rbind(Average.Rating.per.Interval, 
c(1,"marketing",mean(e.1.marketing$rating)))

有关查询列表here

的详细信息

AngularFire2 - 订阅查询

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