0
私のコレクションでは、各ドキュメントはユーザー生成のクイズを表し、タグの配列フィールド、つまり履歴、科学、数学などを含みます。各タグに関連付けられたドキュメントの数。このように見えるユニークなタグリスト内特定の要件の下で集計されたドキュメントの数を取得する
以下の集計結果：{tags:["History", "Science", "Math"]}
db.quizzes.aggregate([
{$unwind: "$tags"},
{$group: {_id:null, tgs: {$addToSet: "$tags"}}},
{$project: {_id:0, tags: "$tgs"}},
])
は、しかし、上記の集約は、各タグを含む文書の数のカウントを得ることができますか？たとえば、3つのヒストリクイズ、2つのサイエンスクイズ、5つのMathクイズがある場合、結果は次のようになります。{tags:[{tag: "History", count: 3}, {tag: "Science", count: 2}, {tag: "Math", count:5}]}
ありがとうございます。
収集文書を含めるように編集：
{
"_id" : ObjectId("57d8ccd573099cb013b462b5"),
"title" : "Presidential Trivia",
"quiz" : "[{\"question\":\"How many presidents were members of the Whig party?\",\"choices\":[\"Two\",\"Three\",\"Four\"],\"correct\":\"2\"},{\"question\":\"Who was the first president to be impeached?\",\"choices\":[\"Warren Harding\",\"Andrew Johnson\",\"Andrew Jackson\"],\"correct\":\"1\"},{\"question\":\"How many presidents died during their presidency?\",\"choices\":[\"Four\",\"Six\",\"Eight\"],\"correct\":\"2\"},{\"question\":\"How many presidents had no party affiliation?\",\"choices\":[\"One\",\"Two\",\"Three\"],\"correct\":\"0\"},{\"question\":\"Who was the only president to serve two non-consecutive terms, making him both the 22nd and 24th president?\",\"choices\":[\"John Quincy Adams\",\"Grover Cleveland\",\"Theodore Roosevelt\"],\"correct\":\"1\"}]",
"correctArray" : "[\"2\",\"1\",\"2\",\"0\",\"1\"]",
"author" : "jake2",
"createTime" : ISODate("2016-09-14T04:06:45.118Z"),
"likes" : 0,
"avgScore" : 0,
"plays" : 3,
"private" : "0",
"tags" : [
"US Presidents",
"American History",
"History"
]
}
{
"_id" : ObjectId("57d8d08973099cb013b462b6"),
"title" : "Finance Quiz",
"quiz" : "[{\"question\":\"Which of these involves the analysis of of a business's financial statements, often used in stock valuation?\",\"choices\":[\"Fundamental Analysis\",\"Technical Analysis\",\"P/E ratio\"],\"correct\":\"0\"},{\"question\":\"What was the name of the bond purchasing program started by the U.S. Federal Reserve in response to the 2008 financial crisis?\",\"choices\":[\"Stimulus Package\",\"Quantitative Easing\",\"Mercantilism\"],\"correct\":\"1\"},{\"question\":\"Which term describes a debt security issued by a government, company, or other entity?\",\"choices\":[\"Bond\",\"Stock\",\"Mutual fund\"],\"correct\":\"0\"},{\"question\":\"Which of these companies has the largest market capitalization (as of October 2015)?\",\"choices\":[\"Ford Motors\",\"Apple\",\"Bank of America\"],\"correct\":\"1\"},{\"question\":\"Which of these is a measure of the size of an economy?\",\"choices\":[\"Purchasing Power Index\",\"Unemployment Rate\",\"Gross Domestic Product\"],\"correct\":\"2\"}]",
"correctArray" : "[\"0\",\"1\",\"0\",\"1\",\"2\"]",
"author" : "jake2",
"createTime" : ISODate("2016-09-14T04:22:33.756Z"),
"tags" : [
"Finance"
],
"likes" : 0,
"avgScore" : 0,
"plays" : 10,
"private" : "0"
}
{
"_id" : ObjectId("57d8d24073099cb013b462b8"),
"title" : "Astronomy Pop Quiz",
"quiz" : "[{\"question\":\"Which of the following are currently (as of November 2015) used by scientists as observational evidence of the existence of dark matter?\",\"choices\":[\"Gravitational Lensing\",\"Specimens of dark matter collected by NASA\",\"Anomalies in planetary orbits\"],\"correct\":\"0\"},{\"question\":\"Which of these emits the most energy?\",\"choices\":[\"Stars\",\"Quasars\",\"Black Holes\"],\"correct\":\"1\"},{\"question\":\"What is it called when light or electromagnetic radiation from an object is increased in wavelength?\",\"choices\":[\"The Jupiter Effect\",\"Redshift\",\"The Observer's Differential\"],\"correct\":\"1\"},{\"question\":\"Who was the first human in space?\",\"choices\":[\"Yuri Gagarin\",\"Alan Shepard\",\"John Glenn\"],\"correct\":\"0\"},{\"question\":\"Which of these is the most dense?\",\"choices\":[\"The Sun\",\"A neutron star\",\"Earth\"],\"correct\":\"1\"}]",
"correctArray" : "[\"0\",\"1\",\"1\",\"0\",\"1\"]",
"author" : "Bertram",
"createTime" : ISODate("2016-09-14T04:29:52.636Z"),
"tags" : [
"Astronomy"
],
"likes" : 1,
"avgScore" : 0,
"plays" : 5,
"private" : "0"
}
{
"_id" : ObjectId("57d8d3c173099cb013b462ba"),
"title" : "Film Trivia",
"quiz" : "[{\"question\":\"Who directed The Godfather trilogy?\",\"choices\":[\"John Huston\",\"Francis Ford Coppola\",\"Martin Scorsese\"],\"correct\":\"1\"},{\"question\":\"What year was the first Ocscar awarded?\",\"choices\":[\"1923\",\"1927\",\"1932\"],\"correct\":\"1\"},{\"question\":\"As of 2010, this and Schindler's List (1993) are the only films to win Best Picture, Director and Screenplay at the Golden Globes, BAFTAs and the Oscars.\",\"choices\":[\"Rain Man\",\"Slumdog Millionaire\",\"Titanic\"],\"correct\":\"1\"},{\"question\":\"In Casablanca, why can't Rick return to America?\",\"choices\":[\"He is indebted to the mob.\",\"He was deported.\",\"No reason is given.\"],\"correct\":\"2\"},{\"question\":\"What was the highest-grossing Western of all time?\",\"choices\":[\"Django Unchained\",\"True Grit\",\"Dances with Wolves\"],\"correct\":\"2\"}]",
"correctArray" : "[\"1\",\"1\",\"1\",\"2\",\"2\"]",
"author" : "Pappy2",
"createTime" : ISODate("2016-09-14T04:36:17.950Z"),
"tags" : [
"Movies"
],
"likes" : 1,
"avgScore" : 0,
"plays" : 8,
"private" : "0"
}
{
"_id" : ObjectId("57ea7f67a58303f01a585e55"),
"title" : "US History Concepts",
"quiz" : "[{\"question\":\"\",\"choices\":[\"\",\"\",\"\"]}]",
"correctArray" : "[]",
"author" : "martha",
"createTime" : ISODate("2016-09-27T14:17:11.627Z"),
"tags" : [
"US History",
"History"
],
"likes" : 0,
"avgScore" : 0,
"plays" : 1,
"private" : "0"
}
dbまたはschemaに保存されたドキュメントデータを投稿してください。 – Sachin
@Sachinありがとう、私は要求された情報を追加しました。 –