How can I create a JSONPath filter expression containing both AND and OR operators?

问题

I have a requirement where i am trying to select objects inside a JSON string by filtering on the presence and/or values of multiple properties of objects inside a JSON array.

Here is an example of my JSON:

{'Fields':[{
  "Sub_Status": "Pending",
  "Status": "Pending",
  "Patient_Gender": "M"
}]}

I want to check this json string using query like this (below query is a SQL query)

string query = TRIM(UPPER(Status)) IN ('PENDING', 'DISPENSED','SHIPMENT') AND TRIM(Patient_Gender) IS NOT NULL

string json_string = {'Fields':[{
  "Sub_Status": "Pending",
  "Status": "Pending",
  "Patient_Gender": "M"
}]};

var test = json_string.Where(query).toString() /// a return of bool = true or false

I tried using JSONPath and also system.linq.dynamic, But no luck.

UPDATE

I need the response in c#. As of now. I tried to use the NewtonSoft.Json SelectToken to select a token using a JSONPath query.

The first part of my query as of now is:

JToken test = s.SelectToken("$.Fields[?(@.Status == 'Pending' || @.Status == 'PENDING' || @.Status == 'SHIPMENT' || @.Status == 'DISPENSED')]");

The second part of my query is:

JToken test = s.SelectToken("$.Fields[?(@.Patient_Gender != '')]");

The problem is with "and" operator -- I do not know how to combine them in a single JSONPath query. Individually the queries are working. I need the syntax for the "and" operator. Any suggestions would be helpful.

回答1:

Newtonsoft's JSONPath implementation does support an AND operator, as can be seen in the source for QueryExpression.cs . It uses the && syntax. Thus if you want to search for fields that have Status == 'Pending' and have a Patient_Gender property present (with any value), you would do:

var query = s.SelectTokens("$.Fields[?(@.Status == 'Pending' && @.Patient_Gender)]");

However, you are mixing && and || operators, and unfortunately the order of precedence of these two operators is undocumented. The JSONPath website says, uselessly, that () is a script expression, using the underlying script engine. And the Newtonsoft documentation says nothing at all beyond referring the reader to that same JSONPath website!

You might want to open a documentation issue with Newtonsoft asking them to clarify the precedence of the || and && operators in JSONPath.

Thus to get your desired query, you have the following options:

I have found from experiment that && and || associate left-to-right with equal precedence. Thus A && B || C means A && (B || C) while A || B && C means A || (B && C)

You apparently want the former. As long as you are willing to depend on undocumented behavior, the following query should work:
```
var filter = "$.Fields[?(@.Patient_Gender && @.Status == 'Pending' || @.Status == 'PENDING' || @.Status == 'SHIPMENT' || @.Status == 'DISPENSED')]";
var query = s.SelectTokens(filter);
var result = query.ToList();
```

You can use Enumerable.Intersect() to combine query results:

var query1 = s.SelectTokens("$.Fields[?(@.Status == 'Pending' || @.Status == 'PENDING' || @.Status == 'SHIPMENT' || @.Status == 'DISPENSED')]");
var query2 = s.SelectTokens("$.Fields[?(@.Patient_Gender)]");
var query = query1.Intersect(query2);

var result = query.ToList();

You can use a Enumerable.Where() to do the filtering and just use SelectTokens() to do the enumeration:

var query = from t in s.SelectTokens("$.Fields[*]")
            where (string)t["Patient_Gender"] != null
            let status = (string)t["Status"]
            where status == "Pending" || status == "PENDING" || status == "SHIPMENT" || status == "DISPENSED"
            select t;

var result = query.ToList();

If you just want to know if anything matches, rather than a list of tokens that match, you can use Any(), e.g.

var result = query.Any();

Incidentally, the following attempts did not work:

Trying to parenthesize the logical operators throws a JsonException: Unexpected character while parsing path query: (:

var filter = "$.Fields[?((@.Status == 'Pending' || @.Status == 'PENDING' || @.Status == 'SHIPMENT' || @.Status == 'DISPENSED') && (@.Patient_Gender))]";
var query = s.SelectTokens(filter);
var result = query.ToList();

Puttting && after || incorrectly selected tokens that matched one of the || clauses but not the && clause:

var filter = "$.Fields[?(@.Status == 'Pending' || @.Status == 'PENDING' || @.Status == 'SHIPMENT' || @.Status == 'DISPENSED' && @.Patient_Gender)]";
var query = s.SelectTokens(filter);
var result = query.ToList();

Here is a fiddle showing the both the working and non-working queries.

回答2:

Actually, you need to Deserialize your json into object or objects (in case of multiple records) and test that object(s).

Go to your Solution Explorer > Right Click => Manage Nuget Packages => Download Netwonsoft.Json, Then create a class with similar json structure :

public class Case
{
    public string Sub_Status { set; get; }
    public string Status { set; get; }
    public string Patient_Gender { set; get; }
}

Then in your Program:

static void Main(string[] args)
{
    string json_string = @"{""Sub_Status"": ""Pending"",
                            ""Status"": ""Pending"",
                            ""Patient_Gender"": ""M""}";

    Case caseObj = Newtonsoft.Json.JsonConvert.DeserializeObject<Case>(json_string);

    List<string> acceptedStatuses = new List<string> { "PENDING", "DISPENSED", "SHIPMENT" };

    bool test = statuses.Any(s => s.Equals(caseObj.Status, StringComparison.OrdinalIgnoreCase))
                            && !string.IsNullOrWhiteSpace(caseObj.Patient_Gender);
}

来源：https://stackoverflow.com/questions/38233178/how-can-i-create-a-jsonpath-filter-expression-containing-both-and-and-or-operato

标签

json

linq

json.net

jsonpath