Class JsonSelector

Provides functionality for retrieving selected values from a root JsonElement.

Inheritance

System.Object

JsonSelector

Inherited Members

System.Object.Equals(System.Object)

System.Object.Equals(System.Object, System.Object)

System.Object.GetHashCode()

System.Object.GetType()

System.Object.MemberwiseClone()

System.Object.ReferenceEquals(System.Object, System.Object)

System.Object.ToString()

Namespace: JsonCons.JsonPath

Assembly: JsonCons.JsonPath.dll

Syntax

public sealed class JsonSelector

Examples

The following example shows how to select values, paths, and nodes from a JSON document

using System;
using System.Diagnostics;
using System.Text.Json;
using JsonCons.JsonPath;

public class Example
{
    public static void Main()
    {
        string jsonString = @"
{
    ""books"":
    [
        {
            ""category"": ""fiction"",
            ""title"" : ""A Wild Sheep Chase"",
            ""author"" : ""Haruki Murakami"",
            ""price"" : 22.72
        },
        {
            ""category"": ""fiction"",
            ""title"" : ""The Night Watch"",
            ""author"" : ""Sergei Lukyanenko"",
            ""price"" : 23.58
        },
        {
            ""category"": ""fiction"",
            ""title"" : ""The Comedians"",
            ""author"" : ""Graham Greene"",
            ""price"" : 21.99
        },
        {
            ""category"": ""memoir"",
            ""title"" : ""The Night Watch"",
            ""author"" : ""David Atlee Phillips"",
            ""price"" : 260.90
        }
    ]
}
        ");

        using JsonDocument doc = JsonDocument.Parse(jsonString);

        var options = new JsonSerializerOptions() {WriteIndented = true};

        // Selector of titles from union of all books with category 'memoir' 
        // and all books with price > 23
        var selector = JsonSelector.Parse("$.books[?@.category=='memoir',?@.price > 23].title");

        Console.WriteLine("Select values");
        IList<JsonElement> values = selector.Select(doc.RootElement);
        foreach (var value in values)
        {
            Console.WriteLine(JsonSerializer.Serialize(value, options));
        }
        Console.WriteLine();

        Console.WriteLine("Select paths");
        IList<JsonLocation> paths = selector.SelectPaths(doc.RootElement);
        foreach (var path in paths)
        {
            Console.WriteLine(path);
        }
        Console.WriteLine();

        Console.WriteLine("Select nodes");
        IList<PathValuePair> nodes = selector.SelectNodes(doc.RootElement);
        foreach (var node in nodes)
        {
            Console.WriteLine($"{node.Path} => {JsonSerializer.Serialize(node.Value, options)}");
        }
        Console.WriteLine();

        Console.WriteLine("Remove duplicate nodes");
        IList<PathValuePair> uniqueNodes = selector.SelectNodes(doc.RootElement, 
                                                    new JsonSelectorOptions{NoDuplicates=true});
        foreach (var node in uniqueNodes)
        {
            Console.WriteLine($"{node.Path} => {JsonSerializer.Serialize(node.Value, options)}");
        }
        Console.WriteLine();
    }
}

Output:

Select values
"The Night Watch"
"The Night Watch"
"The Night Watch"

Select paths
$['books'][3]['title']
$['books'][1]['title']
$['books'][3]['title']

Select nodes
$['books'][3]['title'] => "The Night Watch"
$['books'][1]['title'] => "The Night Watch"
$['books'][3]['title'] => "The Night Watch"

Remove duplicate nodes
$['books'][3]['title'] => "The Night Watch"
$['books'][1]['title'] => "The Night Watch"

Methods

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Parse(String)

Parses a JSONPath string into a JsonSelector, for "parse once, use many times". A JsonSelector instance is thread safe and has no mutable state.

Declaration

public static JsonSelector Parse(string jsonPath)

Parameters

Type	Name	Description
System.String	jsonPath	A JSONPath string.

Returns

Type	Description
JsonSelector	A JsonSelector.

Exceptions

Type	Condition
JsonPathParseException	The `jsonPath` parameter is not a valid JSONPath expression.
System.ArgumentNullException	The `jsonPath` is null.

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Select(JsonElement, JsonSelectorOptions)

Selects values within the root value matched by this JSONPath expression.

Declaration

public IList<JsonElement> Select(JsonElement root, JsonSelectorOptions options = null)

Parameters

Type	Name	Description
System.Text.Json.JsonElement	root	The root value.
JsonSelectorOptions	options	Defines options for processing JSONPath queries.

Returns

Type	Description
System.Collections.Generic.IList<System.Text.Json.JsonElement>	A list of values within the root value matched by this JSONPath expression, or an empty list if none were matched.

Exceptions

Type	Condition
System.InvalidOperationException	Maximum depth level exceeded in recursive descent selector.

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Select(JsonElement, String, JsonSelectorOptions)

Selects values within the root value matched by the provided JSONPath expression. This method parses and applies the expression in one operation.

Declaration

public static IList<JsonElement> Select(JsonElement root, string jsonPath, JsonSelectorOptions options = null)

Parameters

Type	Name	Description
System.Text.Json.JsonElement	root	The root value.
System.String	jsonPath	A JSONPath string.
JsonSelectorOptions	options	Defines options for processing JSONPath queries.

Returns

Type	Description
System.Collections.Generic.IList<System.Text.Json.JsonElement>	A list of values within the root value matched by the provided JSONPath expression, or an empty list if none were matched.

Exceptions

Type	Condition
JsonPathParseException	The `jsonPath` parameter is not a valid JSONPath expression.
System.ArgumentNullException	`jsonPath` is null.
System.InvalidOperationException	Maximum depth level exceeded in recursive descent selector.

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SelectNodes(JsonElement, JsonSelectorOptions)

Selects nodes that represent location-value pairs within the root value matched by this JSONPath expression.

Declaration

public IList<PathValuePair> SelectNodes(JsonElement root, JsonSelectorOptions options = null)

Parameters

Type	Name	Description
System.Text.Json.JsonElement	root	The root value.
JsonSelectorOptions	options	Defines options for processing JSONPath queries.

Returns

Type	Description
System.Collections.Generic.IList<PathValuePair>	A list of PathValuePair representing location-value pairs within the root value matched by this JSONPath expression, or an empty list if none were matched.

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SelectNodes(JsonElement, String, JsonSelectorOptions)

Selects nodes that represent location-value pairs within the root value matched by the JSONPath expression. This method parses and applies the expression in one operation.

Declaration

public static IList<PathValuePair> SelectNodes(JsonElement root, string jsonPath, JsonSelectorOptions options = null)

Parameters

Type	Name	Description
System.Text.Json.JsonElement	root	The root value.
System.String	jsonPath	A JSONPath string.
JsonSelectorOptions	options	Defines options for processing JSONPath queries.

Returns

Type	Description
System.Collections.Generic.IList<PathValuePair>	A list of PathValuePair representing location-value pairs within the root value matched by the provided JSONPath expression, or an empty list if none were matched.

Exceptions

Type	Condition
JsonPathParseException	The `jsonPath` parameter is not a valid JSONPath expression.
System.ArgumentNullException	`jsonPath` is null.
System.InvalidOperationException	Maximum depth level exceeded in recursive descent selector.

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SelectPaths(JsonElement, JsonSelectorOptions)

Selects paths identifying the values within the root value matched by this JSONPath expression.

Declaration

public IList<JsonLocation> SelectPaths(JsonElement root, JsonSelectorOptions options = null)

Parameters

Type	Name	Description
System.Text.Json.JsonElement	root	The root value.
JsonSelectorOptions	options	Defines options for processing JSONPath queries.

Returns

Type	Description
System.Collections.Generic.IList<JsonLocation>	A list of JsonLocation identifying the values within the root value matched by this JSONPath expression, or an empty list if none were matched.

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SelectPaths(JsonElement, String, JsonSelectorOptions)

Selects paths identifying the values within the root value matched by the JSONPath expression. This method parses and applies the expression in one operation.

Declaration

public static IList<JsonLocation> SelectPaths(JsonElement root, string jsonPath, JsonSelectorOptions options = null)

Parameters

Type	Name	Description
System.Text.Json.JsonElement	root	The root value.
System.String	jsonPath	A JSONPath string.
JsonSelectorOptions	options	Defines options for processing JSONPath queries.

Returns

Type	Description
System.Collections.Generic.IList<JsonLocation>	A list of JsonLocation identifying the values within the root value matched by the provided JSONPath expression, or an empty list if none were matched.

Exceptions

Type	Condition
JsonPathParseException	The `jsonPath` parameter is not a valid JSONPath expression.
System.ArgumentNullException	`jsonPath` is null.
System.InvalidOperationException	Maximum depth level exceeded in recursive descent selector.