以不同格式处理数据

Question

我设法创建了一个查询，使用以下脚本从数据库中获取一些数据：

app.get("/diseases", async (req, res) => {
  const rows = await process.postgresql.query(
    "SELECT ds.disease, ds.symptom FROM diseases ds"
  );
  console.log(rows);
  res.status(200).send(JSON.stringify(rows));
});

数据采用以下格式：

[
  { disease: ' boală hipertensivă', symptom: ' durere toracică' },
  {
    disease: ' boală hipertensivă',
    symptom: ' respirație întretăiată'
  },
  { disease: ' boală hipertensivă', symptom: ' amețeală' },
  { disease: ' boală hipertensivă', symptom: ' astenie' },
  { disease: ' boală hipertensivă', symptom: ' toamnă (Fall)' },
  { disease: ' boală hipertensivă', symptom: ' sincopă' },
  { disease: ' diabet', symptom: ' poliurie' }
]

我的问题是如何将此数据转换为如下格式：

{"Hypertensive disease": ["Pain chest", "Shortness of breath", "Dizziness", "Asthenia", "Fall", "Syncope", "Vertigo", "Sweat", "Sweating increased", "Palpitation", "Nausea", "Angina pectoris", "Pressure chest"], "Diabetes": ["Polyuria"]}

Answer 1

您正在尝试对数据进行分组和转置。最好的方法是在数组上使用 .reduce() 函数。这是一个例子：

const arr = [
  { disease: "boală hipertensivă", symptom: " durere toracică" },
  { disease: "boală hipertensivă", symptom: " respirație întretăiată" },
  { disease: "boală hipertensivă", symptom: " amețeală" },
  { disease: "boală hipertensivă", symptom: " astenie" },
  { disease: "boală hipertensivă", symptom: " toamnă (Fall)" },
  { disease: "boală hipertensivă", symptom: " sincopă" },
  { disease: "diabet", symptom: " poliurie" }
];
console.log(arr.reduce((group, row) => {
  // Check if disease group has the disease
  if (typeof group[row.disease] === "undefined") {
    // Initialise an array.
    group[row.disease] = [];
  }
  // Push the symptoms.
  group[row.disease].push(row.symptom.trim());
  // return the updated group.
  return group;
}, {}));

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对于上面的给定输入，我得到这样的响应：

{
  "boală hipertensivă": [
    "durere toracică",
    "respirație întretăiată",
    "amețeală",
    "astenie",
    "toamnă (Fall)",
    "sincopă"
  ],
  "diabet": [
    "poliurie"
  ]
}

Answer 2

return rows.reduce((acc, item) => { if (!!acc[item.disease]) acc[item.disease].push(item.symptom); else acc[item.disease] = [item.symptom]; return acc; }, {})

reduce函数有两个参数——一个迭代处理函数，它累积一个结果，以及初始结果（我们把一个空对象作为初始结果{}）。

迭代处理器有两个参数 - 累加器对象 acc 和当前项 item，它应该 return 新的（或修改的）累加器对象。

在每次迭代中，我们的函数都会检查 acc 是否已经有一个具有 'disease' 值的字段。如果没有' - 它会创建此字段并在其中放入 1 个项目数组 [item.symptom]。如果该字段已经存在，它会将症状推送到该数组。在我们处理数据之后，我们得到以疾病为键的对象，以他们的症状为值的数组。

以不同格式处理数据

Manipulating data in a different format

javascript

node.js