示例 - 索引和查询 JSON 文档
了解如何将 Redis 查询引擎与 JSON 结合使用
此示例说明如何为 JSON 数据创建搜索索引，并且 对索引运行查询。
确保您拥有 Redis 堆栈和node-redis安装。
首先导入依赖项：
import {
createClient,
SchemaFieldTypes,
AggregateGroupByReducers,
AggregateSteps,
} from 'redis';
Connect to the database:
const client = await createClient();
await client.connect();
Create some test data to add to the database:
const user1 = {
name: 'Paul John',
email: 'paul.john@example.com',
age: 42,
city: 'London'
};
const user2 = {
name: 'Eden Zamir',
email: 'eden.zamir@example.com',
age: 29,
city: 'Tel Aviv'
};
const user3 = {
name: 'Paul Zamir',
email: 'paul.zamir@example.com',
age: 35,
city: 'Tel Aviv'
};
Create an index. In this example, only JSON documents with the key prefix user: are indexed. For more information, see Query syntax.
await client.ft.create('idx:users', {
'$.name': {
type: SchemaFieldTypes.TEXT,
AS: 'name'
},
'$.city': {
type: SchemaFieldTypes.TEXT,
AS: 'city'
},
'$.age': {
type: SchemaFieldTypes.NUMERIC,
AS: 'age'
}
}, {
ON: 'JSON',
PREFIX: 'user:'
});
Add the three sets of user data to the database as
JSON objects.
If you use keys with the user: prefix then Redis will index the
objects automatically as you add them. Note that placing
the commands in a Promise.all() call is an easy way to create a
pipeline,
which is more efficient than sending the commands individually.
const [user1Reply, user2Reply, user3Reply] = await Promise.all([
client.json.set('user:1', '$', user1),
client.json.set('user:2', '$', user2),
client.json.set('user:3', '$', user3)
]);
You can now use the index to search the JSON objects. The
query
below searches for objects that have the text "Paul" in any field
and have an age value in the range 30 to 40:
let findPaulResult = await client.ft.search('idx:users', 'Paul @age:[30 40]');
console.log(findPaulResult.total); // >>> 1
findPaulResult.documents.forEach(doc => {
console.log(`ID: ${doc.id}, name: ${doc.value.name}, age: ${doc.value.age}`);
});
Specify query options to return only the city field:
let citiesResult = await client.ft.search('idx:users', '*',{
RETURN: 'city'
});
console.log(citiesResult.total); // >>> 3
citiesResult.documents.forEach(cityDoc => {
console.log(cityDoc.value);
});
Use an
aggregation query
to count all users in each city.
let aggResult = await client.ft.aggregate('idx:users', '*', {
STEPS: [{
type: AggregateSteps.GROUPBY,
properties: '@city',
REDUCE: [{
type: AggregateGroupByReducers.COUNT,
AS: 'count'
}]
}]
});
console.log(aggResult.total); // >>> 2
aggResult.results.forEach(result => {
console.log(`${result.city} - ${result.count}`);
});
Finally, close the connection to Redis.
await client.quit();
See the Redis Query Engine docs
for a full description of all query features with examples.