Reduce不算密鑰

Question

我正在使用couchbase 3.0並玩弄啤酒樣本數據。

我已創建地圖的存在的圖：

function (doc, meta) { 
    if (doc.category && doc.abv) { 
    emit(doc.category, doc.abv); 
    } 
} 

這得到以下輸出：

{"total_rows":2397,"rows":[ 
{"id":"21st_amendment_brewery_cafe-watermelon_wheat","key":"Belgian and French Ale","value":5.5}, 
{"id":"3_fonteinen_brouwerij_ambachtelijke_geuzestekerij-drie_fonteinen_kriek","key":"Belgian and French Ale","value":5}, 
{"id":"3_fonteinen_brouwerij_ambachtelijke_geuzestekerij-oude_geuze","key":"Belgian and French Ale","value":6}, 
{"id":"512_brewing_company-512_wit","key":"Belgian and French Ale","value":5.2}, 
{"id":"512_brewing_company-one","key":"Belgian and French Ale","value":8}, 
{"id":"abbaye_de_maredsous-10","key":"Belgian and French Ale","value":10}, 
{"id":"abbaye_de_maredsous-8","key":"Belgian and French Ale","value":8}, 
{"id":"abbaye_notre_dame_du_st_remy-rochefort_10","key":"Belgian and French Ale","value":11.3}, 
{"id":"abita_brewing_company-satsuma_harvest_wit","key":"Belgian and French Ale","value":5.1}, 
{"id":"affligem_brouwerij-affligem_dubbel","key":"Belgian and French Ale","value":6.8} 
] 
} 

當選擇頂部10

現在我想計數每個類別的啤酒數量。所以我決定添加內建的減少_count。

不幸的是輸出沒有預期的一個，而是：

{"rows":[ 
{"key":null,"value":2397} 
] 
} 

爲什麼我有鑰匙設置爲null，而不是作爲doc.category？

Answer 1

我意識到我查詢視圖時忘記添加組參數。有了這一切，一切工作正常。