JSON

Hyperbee.Expressions.Lab provides two JSON-related expression types:

• JsonExpression – deserializes a JSON string or stream to a typed object using System.Text.Json.
• JsonPathExpression – queries a JsonElement or JsonNode using a JSONPath expression.

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JsonExpression

JsonExpression deserializes a JSON input to a target type.

Factory Method

using static Hyperbee.Expressions.Lab.ExpressionExtensions;

JsonExpression Json( Expression inputExpression, Type targetType = null )

Parameter	Type	Description
inputExpression	Expression	JSON string, Stream, byte[], or JsonElement
targetType	Type?	Target deserialization type. When null, returns JsonElement

Usage

using static System.Linq.Expressions.Expression;
using static Hyperbee.Expressions.Lab.ExpressionExtensions;

// Deserialize a JSON string to a typed object
var jsonString = Constant( """{"Name":"Alice","Age":30}""" );
var person = Variable( typeof(Person), "person" );

var expr = Block(
    [person],
    Assign( person, Json( jsonString, typeof(Person) ) ),
    person
);

var lambda = Lambda<Func<Person>>( expr );
var fn = lambda.Compile( serviceProvider );
var result = fn();
// result.Name == "Alice", result.Age == 30

// Deserialize to JsonElement (no target type)
var element = Json( Constant( """{"key":42}""" ) );

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JsonPathExpression

JsonPathExpression evaluates a JSONPath query against a JsonElement or JsonNode, returning matched nodes.

Factory Method

JsonPathExpression JsonPath( Expression jsonExpression, Expression path )

Parameter	Type	Description
jsonExpression	Expression	A JsonElement or JsonNode to query
path	Expression (string)	JSONPath expression (e.g., "$.store.book[*].author")

Usage

// Query JSON for all names
var json = Constant( """{"users":[{"name":"Alice"},{"name":"Bob"}]}""" );
var element = Variable( typeof(JsonElement), "element" );
var results = Variable( typeof(IEnumerable<JsonElement>), "results" );

var expr = Block(
    [element, results],
    Assign( element, Json( json ) ),
    Assign( results, JsonPath( element, Constant( "$.users[*].name" ) ) ),
    results
);

Combining Fetch, Json, and JsonPath

var response = Variable( typeof(string), "response" );
var names = Variable( typeof(IEnumerable<JsonElement>), "names" );

var asyncBlock = BlockAsync(
    [response, names],
    Assign( response, Await( ReadText( Fetch( Constant( "https://api.example.com/users" ) ) ) ) ),
    Assign( names, JsonPath( Json( response ), Constant( "$.data[*].name" ) ) ),
    names
);

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Notes

• JsonExpression uses System.Text.Json.JsonSerializer internally.
• For custom JsonSerializerOptions, the options are resolved from IServiceProvider when Compile(serviceProvider) is called.
• JsonPathExpression supports RFC 9535 JSONPath syntax via the Hyperbee.Json library.
• See Fetch for HTTP integration.