I'm parsing some JSON data I receive from a server using the built-in System.Text.Json module.
Here's an example class that I would use:
public class Something
{
[JsonPropertyName("items")]
public Item[] Items { get; set; }
}
The JSON data for this is usually received like the following, and it's properly parsed with JsonSerializer.Deserialize<Something>():
{
"items": [ { ... }, { ... }, { ... } ]
}
However, when there's no items, the server instead returns an empty object, which causes an exception because it expected an array.
{
"items": {}
}
Is there any way I could set it so that an empty object would be considered as an empty array? I've seen that you can make a custom JSON converter but I struggled to get it working.
you don't need any fansy custom converters in your case. Just try this
public class Something
{
[JsonPropertyName("items")]
public object _items
{
get
{
return Items;
}
set
{
if (((JsonElement)value).ValueKind.ToString() == "Array")
{
Items = ((JsonElement)value).Deserialize<Item[]>();
}
}
}
[System.Text.Json.Serialization.JsonIgnore]
public Item[] Items { get; set; }
}
and if you don't need to serialize it back, you can even remove _items get at all
Related
I have this JSON:
{
"AAPL": { "price": "131.85000" },
"eur/usd": { "price": "1.06290" },
"msft": { "price": "238.76000" }
}
When I try to deserialize this into a dictionary it comes back as null.
I am using the TwelveDataAPI.
https://twelvedata.com/docs#real-time-price
I have tried creating a simple class that will allow me to deserialize this JSON even if there are different tickers and different amounts of them.
My class:
public class CurrentPriceClass
{
public class Root
{
public Dictionary<string, Price> Prices { get; set; }
}
public class Price
{
public string price { get; set; }
}
}
But when I try to deserialize it, it comes back as null, and I cannot iterate over it:
CurrentPriceClass.Root priceRoot = JsonConvert.DeserializeObject<CurrentPriceClass.Root>(
dataJson);
foreach (KeyValuePair<string, CurrentPriceClass.Price> price in priceRoot.Prices)
{
Console.WriteLine($"{price.Key}: {price.Value.price}");
}
The error I get when iterating is:
Object reference not set to an instance of an object.
When debugging priceRoot is null.
I am assuming that this is a problem with my class.
Deserialize as Dictionary<string, CurrentPriceClass.Price> without needing the root class (CurrentPriceClass).
Dictionary<string, CurrentPriceClass.Price> priceRoot = JsonConvert.DeserializeObject<Dictionary<string, CurrentPriceClass.Price>>(dataJson);
foreach (KeyValuePair<string, CurrentPriceClass.Price> price in priceRoot)
{
Console.WriteLine($"{price.Key}: {price.Value.price}");
}
Demo # .NET Fiddle
I'm integrating to an API that returns this model from almost endpoints
{
meta: { ... },
data: { ... }
}
But for some calls, the data is an array of the same kind of objects
{
meta: { ... },
data: [
{ ... },
{ ... }
]
}
I want to use HttpContent.ReadAsAsync<ResponseObj> to convert both of these to my C# classes, and the I've set up the Response class like this:
public class ResponseObj {
public MetaObj Meta {get;set;}
public DataObj[] Data {get;set;}
}
Somewhat expectedly, I get an exception when trying to parse the first response. Is it possible to tell the JSON parser to handle the single data object and return a single-element array?
The only other solution I can see is to create separate ResponseObj definitions for the two different response types.
Create your ResponseObj as a generic class.
public class ResponseObj<T> {
public MetaObj Meta {get;set;}
public T Data {get;set;}
}
You can deserialize json using HttpContent.ReadAsAsync<ResponseObj<DataObj>> or HttpContent.ReadAsAsync<ResponseObj<DataObj[]>>
I'm trying to construct a request body for a REST api call, and I need to create a JSON object with the list of properties I want to get back.
For eg: I have this C# object that I want to get back:
public class SomeProperties
{
public string TicketNumber { get; set; }
public Driver Driver { get; set; }
}
public class Driver
{
public string Name { get; set; }
}
To get this back, I need to put these properties in a JSON request body like this:
"properties": [
"ticketNumber",
"driver.name"
]
My attempt looks like this:
private string FetchProperties()
{
var fetchProperties = new
{
properties = new List<string>
{
"ticketNumber",
"driver.name"
}
};
var jsonResult = JsonConvert.SerializeObject(fetchProperties, Formatting.None);
return jsonResult;
}
But I don't want to hard code the properties like that.
So is there any way I can use property names from the object I want, to put in the list of strings that I made in the method above?
Thank You!
If I understand correctly,you need Metadata of model.
if you use EntityFramework, you can get metadata of your model
from this Code
and call BuildJsonMetadata() function
and if you use other mapper, I dont see any exist tool for generate metadata of model and you must generate it handly
somthing like this
First of, if you serialize the class you have (SomeProperties), you will not get driver.name. Instead you will get a string like this one that shows driver as an object,
{
properties : {
"ticketNumber" : "stringvalue",
"driver" : {
"name" : "stringValue"
}
}
}
That said, if you are interested in getting a json like this,
"properties": [
"ticketNumber",
"driver.name"
]
you will need a class (very simple one at that) that contains only a list of strings. properties is not an array of objects, but simply strings. From the looks of the FetchProperties method, you are creating an object with fetchProperties as the RootObject. Try something like this,
public class MyClass
{
[JsonProperty("fetchProperties")]
public Fetch FetchProperties { get; set; }
}
public class Fetch
{
[JsonProperty("properties")]
public List<string> Properties { get; set; }
}
private string FetchProperties()
{
MyClass obj = new MyClass()
{
FetchProperties = new Fetch()
{
Properties = new List<string>() { "ticketNumber", "driver.Name" }
}
};
return JsonConvert.SerializeObject(obj); // Formatting.None is by default
}
Now its your choice to hard code these values or, pass them as arguments or use a local variable that contains a list of all the strings you intend to store as "properties". You cant use enums because of violation in naming convention (driver.name) so these options should suffice.
I've run into a type of issue.
I have an ErrorModel class, bare bones, that was inheriting ICollection.
public class ErrorsModel : ICollection<string>
{
private ICollection<string> Errors { get; set; }
public bool HasErrors { get { return Errors != null && Errors.Any(); } }
public string PartialView { get; set; }
}
Omitted the ICollection imp. as it is standard
When Returned by a controllers Action Json method
return Json(Errors)
The result is the private Errors object
[
"Select a Country",
"Select a City"
]
However when you remove the inheritance you get a complete serialization of the object.
{
"Count": 2,
"HasErrors": true,
"IsReadOnly": false
}
So my question is what is causing the odd serialization behavior when inheriting?
Your JSON serializer is treating all collection classes as arrays.
JSON does not support mixtures of arrays and objects.
This is the JSON object I am receiving from a GET request:
{
"data": {
"valve_maker": [],
"water_volume": [
"15L",
"20L",
"..."
],
"cylinder_manufacturer": [
"Tianhai"
],
"qc_stamp": [
"TS"
],
"reference_standard": [
"GB 5099"
],
"production_licence": [
"TS2210752-2016"
],
"valve_production_licence": [
"TSF210030"
],
"rate_of_residual_deformation": {
"1": "<3%",
"2": "<10%"
},
"material_number": {
"1": "30CrMo",
"2": "34CrMo4",
"3": "..."
},
"heat_treatment": {
"1": "...",
"2": "..."
},
"drawing_number": {
"1": "...",
"2": "..."
},
"cylinder_thickness": []
}
right now, I am able to parse JSON objects with a simpler structure like :
{
"data": [
{
"gas_id": "ID of the gas",
"gas_name": "Gas name"
}
]
by using something like this:
private void jsonparsegas(string res)
{
JObject par = JObject.Parse(res);
foreach (JToken data in par["data"].Children())
{
string id = data["gas_id"].ToString();
string name = data["gas_name"].ToString();
if (this.cmbCylType.Items.Contains(name) == false)
{
this.cmbCylType.Items.Add(name);
}
}
}
When I try to apply the same thing to the more complicated JSON object, I get an error:
private void jsonparsecoc(string res)
{
//JObject par = JObject.Parse(res);
var jObj = (JObject)Newtonsoft.Json.JsonConvert.DeserializeObject(res);
foreach (var child in jObj["data"].Children())
{
string vMaker = child["valve_maker"].ToString(); //error thrown here right away
string wVolume = child["water_volume"].ToString();
string cMan = child["cylinder_manufacturer"].ToString();
string QC = child["qc_stamp"].ToString();
string rStandard = child["reference_standard"].ToString();
string pLicence = child["production_licence"].ToString();
string VPL = child["valve_production_licence"].ToString();
string rrd = child["rate_of_residual_deformation"].ToString();
string mNum = child["material_number"].ToString();
string hTreatment = child["heat_treatment"].ToString();
string dNum = child["drawing_number"].ToString();
string cThick = child["cylinder_thickness"].ToString();
}
Cannot access child value on Newtonsoft.Json.Linq.JProperty
I have tried a few different things I found on StackOverflow, but I don't really understand how Deserializing of the objects works. The simpler parsing works just fine, and allows me to add all "gas_name"s that I receive from my GET request to a combobox. The format the first "valve_maker" child of "data" seems to have the same structure as "gas_id" or "gas_name" in the more similar JSON object, but this is where I receive the error right away. If I had to guess at a cause for the error, I'd say it has something to do with the difference between using
"valve_maker": []
and using
"gas_id": "ID of the gas"
in the objects. also I notice "data" is followed by [] brackets in the simpler one, and {} in the more complicated one.
If anyone could link to some good reading material, or offer a good explanation of a solution/what's going on, I'd really appreciate it.
This part is the key to the problem you're having:
in the objects. also I notice "data" is followed by [] brackets in the simpler one, and {} in the more complicated one.
In JSON,
[] brackets enclose an array
{} brackets enclose an object
In both code examples, you are digging into the object by looping through the results using par["data"].Children(). To be consistent with the JSON model, JSON.NET defines different behavior for resolving children of objects and arrays. The children of an object are its properties and the children of an array are its items.
In your code, the input to jsonparsegas is an array of simple objects with 2 properties where the input to jsonparsecoc is a single complex objects with many properties.
In jsonparsegas, the Children() call gives you an array of all the simple gas objects. You loop through these objects and extract the values of "gas_id" and "gas_name" for each object. In your example data, there only happens to be one gas object so your code only executes once.
In jsonparsecoc, the Children() call actually gives you property values for the properties of the complex object, since the result is an object and not an array. So, when you loop through this result you can't access things like "valve_maker", because they are defined on the complex object and you have already stepped into the value for valve_maker then this executes.
The solution is simple. Don't loop through the properties in jsonparsecoc. Instead of foreach(var child in jObj["data"].Children()) you need something like var child = jObj["data"];. This will give you the reference to the object that actually contains each of the properties you are trying to access.
#smartcaveman did a good job of explaining what is going wrong with your code. However, you might find your data a little easier to process if you defined strongly-typed classes for it like this:
class RootObject
{
public Data Data { get; set; }
}
class Data
{
[JsonProperty("valve_maker")]
public List<string> ValveMaker { get; set; }
[JsonProperty("water_volume")]
public List<string> WaterVolume { get; set; }
[JsonProperty("cylinder_manufacturer")]
public List<string> CylinderManufacturer { get; set; }
[JsonProperty("qc_stamp")]
public List<string> QCStamp { get; set; }
[JsonProperty("reference_standard")]
public List<string> ReferenceStandard { get; set; }
[JsonProperty("production_licence")]
public List<string> ProductionLicense { get; set; }
[JsonProperty("valve_production_licence")]
public List<string> ValveProductionLicense { get; set; }
[JsonProperty("rate_of_residual_deformation")]
public Dictionary<string, string> RateOfResidualDeformation { get; set; }
[JsonProperty("material_number")]
public Dictionary<string, string> MaterialNumber { get; set; }
[JsonProperty("heat_treatment")]
public Dictionary<string, string> HeatTreatment { get; set; }
[JsonProperty("drawing_number")]
public Dictionary<string, string> DrawingNumber { get; set; }
[JsonProperty("cylinder_thickness")]
public List<string> CylinderThickness { get; set; }
}
You can deserialize the JSON to your classes like this:
RootObject obj = JsonConvert.DeserializeObject<RootObject>(json);
Demo here: https://dotnetfiddle.net/p0D7ze
public class Test{
public Data data{get;set;}
}
public class Data{
public List<string> Value_maker{get;set;}
public List<String> Water_Volume{get;set;}
public List<String> cylinder_manufacturer{get;set;}
}
Create Class structure Like that and after that use to deserialize
Jsonconvert.DeserializeObject(JsonString)
it will convert json into proper object, keep in mind structure should be proper and property name should be same as your json property
Hope It will Help you