Index and query documents

Learn how to use Redis Search with JSON and hash documents.

This example shows how to create a search index for JSON documents and run queries against the index. It then goes on to show the slight differences in the equivalent code for hash documents.

Note:
From v6.0.0 onwards, redis-py uses query dialect 2 by default. Redis Search methods such as ft().search() will explicitly request this dialect, overriding the default set for the server. See Query dialects for more information.

Initialize

Make sure that you have Redis Open Source or another Redis server available. Also install the redis-py client library if you haven't already done so.

Add the following dependencies. All of them are applicable to both JSON and hash, except for the Path class, which is specific to JSON (see Path for a description of the JSON path syntax).

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Foundational: Import required libraries for Redis Search, JSON operations, and search functionality
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import redis
from redis.commands.json.path import Path
import redis.commands.search.aggregation as aggregations
import redis.commands.search.reducers as reducers
from redis.commands.search.field import TextField, NumericField, TagField
from redis.commands.search.index_definition import IndexDefinition, IndexType
from redis.commands.search.query import Query
import redis.exceptions
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Create data

Create some test data to add to your database. The example data shown below is compatible with both JSON and hash objects.

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Foundational: Define sample user data structures for indexing and querying
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user1 = {
    "name": "Paul John",
    "email": "[email protected]",
    "age": 42,
    "city": "London"
}

user2 = {
    "name": "Eden Zamir",
    "email": "[email protected]",
    "age": 29,
    "city": "Tel Aviv"
}

user3 = {
    "name": "Paul Zamir",
    "email": "[email protected]",
    "age": 35,
    "city": "Tel Aviv"
}
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Add the index

Connect to your Redis database. The code below shows the most basic connection but see Connect to the server to learn more about the available connection options.

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Foundational: Establish a connection to a Redis server for query operations
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r = redis.Redis(decode_responses=True)
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The example uses an index called idx:users for JSON documents and adds some JSON documents with the user: key prefix. To avoid errors, first delete any existing index or documents whose names that might conflict with the example:

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Foundational: Clean up existing indexes and documents to prepare for fresh example data
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try:
    r.ft("idx:users").dropindex(True)
except redis.exceptions.ResponseError:
    pass

r.delete("user:1", "user:2", "user:3")
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Create an index for the JSON data. The code below specifies that only JSON documents with the key prefix user: are indexed. For more information, see Query syntax.

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Foundational: Create a search index for JSON documents with field definitions and key prefix filtering
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schema = (
    TextField("$.name", as_name="name"),
    TagField("$.city", as_name="city"),
    NumericField("$.age", as_name="age")
)

indexCreated = r.ft("idx:users").create_index(
    schema,
    definition=IndexDefinition(
        prefix=["user:"], index_type=IndexType.JSON
    )
)
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Add the data

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:

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Foundational: Store JSON documents in Redis with automatic indexing based on key prefix
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user1Set = r.json().set("user:1", Path.root_path(), user1)
user2Set = r.json().set("user:2", Path.root_path(), user2)
user3Set = r.json().set("user:3", Path.root_path(), user3)
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Query the data

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:

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Query with filters: Search JSON documents using text matching and numeric range filters to find specific records
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findPaulResult = r.ft("idx:users").search(
    Query("Paul @age:[30 40]")
)

print(findPaulResult)
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Specify query options to return only the city field:

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Query with field projection: Retrieve only specific fields from search results to reduce data transfer
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citiesResult = r.ft("idx:users").search(
    Query("Paul").return_field("$.city", as_field="city")
).docs

print(citiesResult)
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Use an aggregation query to count all users in each city.

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Aggregation queries: Use GROUP BY and COUNT operations to summarize and analyze indexed data
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req = aggregations.AggregateRequest("*").group_by(
    '@city', reducers.count().alias('count')
)

aggResult = r.ft("idx:users").aggregate(req).rows
print(aggResult)
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Differences with hash documents

Indexing for hash documents is very similar to JSON indexing but you need to specify some slightly different options.

When you create the schema for a hash index, you don't need to add aliases for the fields, since you use the basic names to access the fields anyway. Also, you must use HASH for the IndexType when you create the index.

First delete any existing index or documents whose names might conflict with the hash example:

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Foundational: Clean up existing hash indexes and documents to prepare for fresh example data
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try:
    r.ft("hash-idx:users").dropindex(True)
except redis.exceptions.ResponseError:
    pass

r.delete("huser:1", "huser:2", "huser:3")
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Create a new index called hash-idx:users, which is otherwise the same as the idx:users index used for JSON documents in the previous examples:

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Foundational: Create a search index for hash documents with HASH index type and field definitions
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hashSchema = (
    TextField("name"),
    TagField("city"),
    NumericField("age")
)

hashIndexCreated = r.ft("hash-idx:users").create_index(
    hashSchema,
    definition=IndexDefinition(
        prefix=["huser:"], index_type=IndexType.HASH
    )
)
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You use hset() to add the hash documents instead of json().set(), but the same flat userX dictionaries work equally well with either hash or JSON:

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Foundational: Store hash documents in Redis with automatic indexing based on key prefix
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huser1Set = r.hset("huser:1", mapping=user1)
huser2Set = r.hset("huser:2", mapping=user2)
huser3Set = r.hset("huser:3", mapping=user3)
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The query commands work the same here for hash as they do for JSON (but the name of the hash index is different). The format of the result is almost the same except that the fields are returned directly in the result Document object instead of in an enclosing json dictionary:

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Query with filters: Search hash documents using text matching and numeric range filters (same as JSON queries)
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findPaulHashResult = r.ft("hash-idx:users").search(
    Query("Paul @age:[30 40]")
)

print(findPaulHashResult)
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More information

See the Redis Search docs for a full description of all query features with examples.

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