77 lines
2.5 KiB
Markdown
77 lines
2.5 KiB
Markdown
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---
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id: 587d7fb9367417b2b2512c12
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title: 通過鏈式調用輔助查詢函數來縮小搜索結果
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challengeType: 2
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forumTopicId: 301533
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dashedName: chain-search-query-helpers-to-narrow-search-results
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---
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# --description--
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如果不給 `Model.find()`（或者別的搜索方法）的最後一個參數傳入回調函數, 查詢將不會執行。 可以將查詢條件存儲在變量中供以後使用， 也可以通過鏈式調用這類變量來構建新的查詢字段。 實際的數據庫操作會在最後調用 `.exec()` 方法時執行。 必須把回調函數傳給最後一個方法。 Mongoose 提供了許多輔助查詢函數, 這裏使用最常見的一種。
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# --instructions--
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修改 `queryChain` 函數來查詢喜歡 `foodToSearch` 食物的人。 同時，需要將查詢結果按 `name` 屬性排序， 查詢結果應限制在兩個 document 內，並隱藏 age 屬性。 請鏈式調用 `.find()`、`.sort()`、`.limit()` 和 `.select()`，並在最後調用 `.exec()`， 並將 `done(err, data)` 回調函數傳入 `exec()`。
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# --hints--
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應該成功地鏈式調用輔助查詢函數。
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```js
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(getUserInput) =>
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$.ajax({
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url: getUserInput('url') + '/_api/query-tools',
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type: 'POST',
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contentType: 'application/json',
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data: JSON.stringify([
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{ name: 'Pablo', age: 26, favoriteFoods: ['burrito', 'hot-dog'] },
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{ name: 'Bob', age: 23, favoriteFoods: ['pizza', 'nachos'] },
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{ name: 'Ashley', age: 32, favoriteFoods: ['steak', 'burrito'] },
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{ name: 'Mario', age: 51, favoriteFoods: ['burrito', 'prosciutto'] }
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])
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}).then(
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(data) => {
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assert.isArray(data, 'the response should be an Array');
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assert.equal(
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data.length,
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2,
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'the data array length is not what expected'
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);
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assert.notProperty(
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data[0],
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'age',
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'The returned first item has too many properties'
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);
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assert.equal(
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data[0].name,
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'Ashley',
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'The returned first item name is not what expected'
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);
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assert.notProperty(
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data[1],
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'age',
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'The returned second item has too many properties'
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);
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assert.equal(
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data[1].name,
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'Mario',
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'The returned second item name is not what expected'
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);
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},
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(xhr) => {
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throw new Error(xhr.responseText);
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}
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);
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```
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# --solutions--
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```js
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/**
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Backend challenges don't need solutions,
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because they would need to be tested against a full working project.
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Please check our contributing guidelines to learn more.
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*/
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```
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