I got a Problem with my API. I want to get a random amout of questions back.
The Model of my question has a list of answers and hints:
public class Question
{
public int Id { get; set; }
public string Text { get; set; }
public string Explanation { get; set; }
public Category Category { get; set; }
public ICollection<Answer> Answers { get; set; }
public ICollection<Hint> Hints { get; set; }
}
normally if i call my get method i get a json with all the lists back
return _ctx.Questions.Include(x => x.Answers).Include(x => x.Hints).ToList();
{
"id": 1,
"text": "Test?",
"explanation": "Test",
"category": null,
"answers": [
{
"id": 1,
"text": "Test",
"isCorrect": true
},
{
"id": 2,
"text": "Test1",
"isCorrect": false
},
{
"id": 3,
"text": "Test2",
"isCorrect": false
},
{
"id": 4,
"text": "Test3",
"isCorrect": false
}
],
"hints": [
{
"id": 1,
"text": "..."
},
{
"id": 2,
"text": "..."
}
]
}
But if I want to get random picks with a orderby i only got empty lists
return _ctx.Questions.Include(x => x.Answers).Include(x => x.Hints).OrderBy(o => Guid.NewGuid()).Take(amount).ToList();
{
"id": 1,
"text": "test",
"explanation": "..-",
"category": null,
"answers": [],
"hints": []
}
Does someone have a Idea to fix this?
After sql need to be a list. I got a similar problem a long time ago.
Hope it s help, was with an older version of Ef.
So you have to add a ToList before the OrderBy.
return _ctx.Questions.Include(x => x.Answers).Include(x => x.Hints).ToList().OrderBy(o => Guid.NewGuid()).Take(amount).ToList();
Related
I am attempting to deserialize a tree of JSon objects I get back into a DTO. The tree can be up to 4 levels deep, and over 1200 nodes. The code is C# using Newtonsoft.Json for deserialization.
EDIT
The JSon looks like:
[
{
"id": 1095,
"name": "Item1-1",
"children": [
{
"id": 1097,
"name": "Item2-2",
"children": [
{
"id": 18,
"name": "Item3-3",
"children": [
{
"id": 19,
"name": "Item4-4",
"children": [],
"level": 4,
"parentId": 18
},
{
"id": 20,
"name": "Item5-4",
"children": [],
"level": 4,
"parentId": 18
}
],
"level": 3,
"parentId": 1097
}
],
"level": 2,
"parentId": 1095
}
],
"level": 1,
"parentId": null
}
]
My DTO is similar to this:
public class MyDTO
{
[JsonProperty("id")]
public int Id { get; set; }
[JsonProperty("name")]
public string Name { get; set; }
[JsonProperty("children")]
public MyDTO[] Children { get; set; }
[JsonProperty("level")]
public int Level { get; set; }
[JsonProperty("parentId")]
public int ParentId { get; set; }
public MyDTO()
{
}
}
I like Brian Rogers' solution in this link, which deserializes the json into objects:
How do I use JSON.NET to deserialize into nested/recursive Dictionary and List?
public static class JsonHelper
{
public static object Deserialize(string json)
{
return ToObject(JToken.Parse(json));
}
private static object ToObject(JToken token)
{
switch (token.Type)
{
case JTokenType.Object:
return token.Children<JProperty>()
.ToDictionary(prop => prop.Name,
prop => ToObject(prop.Value));
case JTokenType.Array:
return token.Select(ToObject).ToList();
default:
return ((JValue)token).Value;
}
}
}
I call the JSonHelper with object obj = JsonHelper.Deserialize(jsonString);
I have been experimenting with converting this code into a method to convert to MyDTO, but I keep running into compiler errors. I have attempted to simply convert the JValue casts with MyDTO and move on to the List with a List.
My goal is to call MyDTO obj = JsonHelp.Deserialize(jsonString) and get the tree of MyDTO objects back. Is it possible to do what I am trying, or should I find a way to cast each object to MyDTO?
First your JSON is missing a brakcet ], then your model needs a nullable parentId. Making a couple simple changes you can then you JsonConvert.DeserializeObject<IEnumerable<MyDTO>>(json).
So your JSON should look like this:
[
{
"id": 1095,
"name": "Item1-1",
"children": [
{
"id": 1097,
"name": "Item2-2",
"children": [
{
"id": 18,
"name": "Item3-3",
"children": [
{
"id": 19,
"name": "Item4-4",
"children": [],
"level": 4,
"parentId": 18
},
{
"id": 20,
"name": "Item5-4",
"children": [],
"level": 4,
"parentId": 18
}
],
"level": 2,
"parentId": 1095
}],
}],
"level": 1,
"parentId": null
}
]
And can be deserialized with this model:
public class MyDTO
{
public int Id { get; set; }
public string Name { get; set; }
public MyDTO[] Children { get; set; }
public int Level { get; set; }
public int? ParentId { get; set; }
}
Using this code:
var dto = JsonConvert.DeserializeObject<IEnumerable<MyDTO>>(json);
I'm wondering if someone can elucidate a method to sort a list of objects based on a child object's attribute.
I'm working with the following model:
public class Content
{
public string Id { get; set; }
public List<ContentAttribute> Attributes { get; set; }
}
public class ContentAttribute
{
public string Value { get; set; }
public string Id { get; set; }
public string Name { get; set; }
}
Some sample data:
[
{
"Id": "123",
"Attributes": [
{
"Value": "abc",
"Id": "1a",
"Name": "name1"
},
{
"Value": "ghi",
"Id": "2b",
"Name": "name2"
}
]
},
{
"Id": "456",
"Attributes": [
{
"Value": "abc",
"Id": "1a",
"Name": "name2"
},
{
"Value": "def",
"Id": "2b",
"Name": "name3"
}
]
},
{
"Id": "789",
"Attributes": [
{
"Value": "abc",
"Id": "1a",
"Name": "name1"
},
{
"Value": "def",
"Id": "2b",
"Name": "name2"
}
]
}
]
How can I sort the Content objects by the Value of a specific attribute Name? For example, I would like to sort the above data by the Value of 'name2',
meaning the result would be
[
{"Id" : "456"},
{"Id" : "789"},
{"Id" : "123"}
]
Any help is greatly appreciated. (Using c#).
If Attributes always has an element with name name2 and you want an exception if it doesn't then:
var sorted = contents.OrderBy(c => c.Attributes.First(a => a.Name == "name2").Value).ToList();
Or if name2 could be missing and it's not deal breaker then use FirstOrDefault
var sorted = contents.OrderBy(c => c.Attributes.FirstOrDefault(a => a.Name == "name2")?.Value).ToList();
im facing a problem with probably selfreference Looping:
Model:
public class ProtectedAccount
{
public int Id { get; set; }
[DatabaseGenerated(DatabaseGeneratedOption.Computed)]
public DateTime Created { get; private set; }
public DateTime? Changed { get; set; }
public bool Disabled { get; set; }
public virtual ICollection<ProtectedAccountMember> Members { get; set; }
public virtual ProtectedAccountType Type { get; set; }
}
public class ProtectedAccountMember
{
public int Id { get; set; }
[StringLength(300)]
public string Name { get; set; }
[Index]
public virtual ProtectedAccount ProtectedAccount { get; set; }
}
Controller:
[ResponseType(typeof(ProtectedAccount))]
[Route("ProtectedAccounts/{id}/Members")]
[HttpGet]
public IHttpActionResult GetProtectedAccountMembers(int id)
{
var protectedAccount = db.ProtectedAccounts.Find(id);
if (protectedAccount == null)
{
return NotFound();
}
return Ok(protectedAccount.Members.ToList());
}
the data wich i receive for an GET seems to Loop recursive through all navigations:
[
{
"ProtectedAccount": {
"Members": [
{
"Id": 2,
"Name": "XXX, XX",
},
{
"Id": 3,
"Name": "XX, XX",
}
],
"Type": null,
"Id": 25,
"ObjectGUID": "76bf65e7-af60-4fe8-b3e1-90afbfd65b65",
"Name": "XXX",
},
"Id": 1,
"Name": "test",
},
{
"ProtectedAccount": {
"Members": [
{
"Id": 1,
"Name": "test",
},
{
"Id": 3,
"Name": "XX, XX",
"SamAccountName": "XX",
"Disabled": false
}
],
"Type": null,
"Id": 25,
"ObjectGUID": "76bf65e7-af60-4fe8-b3e1-90afbfd65b65",
"Name": "XXXX",
},
"Id": 2,
"Name": "XX, XX",
},
{
"ProtectedAccount": {a
"Members": [
{
"Id": 1,
"Name": "test",
"SamAccountName": "XXX",
"Disabled": false
},
{
"Id": 2,
"Name": "XX, XX",
"SamAccountName": "XX",
"Disabled": false
}
],
"Type": null,
"Id": 25,
"ObjectGUID": "76bf65e7-af60-4fe8-b3e1-90afbfd65b65",
"Name": "XXX",
},
"Id": 3,
"Name": "XX, XX",
}
]
There is only one "ProtectedAccount" in the database. DO i have to use DTO to overcome this issue? I tried some configuration via the json formatsettings but didnt get any better results.
From your code, you are only returing the protectedAccount.Members, hence you could do a projection query as below
var results = ctx.ProtectedAccountMembers
.Where(member => member.ProtectedAccount.Id == protectedAccount.Id)
.Select(member => new { member.Id, member.Name }).ToList();
I'm currently trying to read Json file (named initial_data.json) which reside in the folder DataModels in my Project folder. The problem I'm having is it won't read the file. I have tried the following code to read the file to json string (which I will use it to deserialize later, so I've tried to display it into resultTextBlock) and nothing has came out.
Here's my Json file format
{
"brands": [
{
"id": "AUD",
"name": "AUDI",
"sort": "99",
"active": true
},
{
"id": "BEN",
"name": "MERCEDES-BENZ",
"sort": "6",
"active": true
},
{
"id": "BMW",
"name": "BMW",
"sort": "7",
"active": true
},
{
"id": "CHE",
"name": "CHEVROLET",
"sort": "8",
"active": true
}
],
"models": [
{
"id": "100",
"name": "CIVIC",
"brandID": "HON",
"size": null,
"year": "-",
"active": true
},
{
"id": "101",
"name": "CRV",
"brandID": "HON",
"size": null,
"year": "-",
"active": true
},
{
"id": "102",
"name": "CRVEXI",
"brandID": "HON",
"size": null,
"year": "-",
"active": true
},
{
"id": "103",
"name": "GDYSSEY",
"brandID": "HON",
"size": null,
"year": "-",
"active": true
}
]
}
Here's my json Class
public class Brand
{
[JsonProperty("id")]
public string id { get; set; }
[JsonProperty("name")]
public string name { get; set; }
[JsonProperty("sort")]
public string sort { get; set; }
[JsonProperty("active")]
public bool active { get; set; }
[JsonProperty("path")]
public string path { get; set; }
}
public class Model
{
[JsonProperty("id")]
public string id { get; set; }
[JsonProperty("name")]
public string name { get; set; }
[JsonProperty("brandID")]
public string brandID { get; set; }
[JsonProperty("size")]
public object size { get; set; }
[JsonProperty("year")]
public string year { get; set; }
[JsonProperty("active")]
public bool active { get; set; }
}
And here's how I write my reading function
private async Task readJsonAsync()
{
// Notice that the write **IS** identical ... except for the serializer.
string content = String.Empty;
var myStream = await ApplicationData.Current.LocalFolder.OpenStreamForReadAsync(JSONFILENAME);
using (StreamReader reader = new StreamReader(myStream))
{
content = await reader.ReadToEndAsync();
}
resultTextBlock.Text = content;
}
Any help would be appreciated
think there might be some issue with the path you specified for the file name.
Please put your file in assets folder and follow the below code
var fileStream = File.OpenRead("Assets/" + "sampleJson.txt");//You can specify your file name here.
using (StreamReader reader = new StreamReader(fileStream))
{
var content = await reader.ReadToEndAsync();
}
First: I'm new to using JSON, and I used the answers on here to use Json.Net to deserialize data from a Pokemon API into a C# class (Pokemon class). I used http://json2csharp.com to help me define my class and it looks like this:
public class Pokemon
{
public Pokemon(string json)
{
JsonConvert.PopulateObject(json, this, PokeApi.JsonSerializerSettings);
}
[JsonProperty("name")]
public string Name { get; set; }
[JsonProperty("evolutions")]
public Evolutions evolutions { get; set; }
[JsonProperty("national_id")]
public int national_id { get; set; }
}
with a bunch of other properties like resource_uri, attack stat, etc.
As the answer offered on the aforementioned link said, I used JsonConvert.DeserializeObject(json) like so:
public Pokemon GetPokemon(int nationalId)
{
using (WebClient client = new WebClient())
{
var json = client.DownloadString("http://pokeapi.co/api/v1/pokemon/" + nationalId + "/");
var output = JsonConvert.DeserializeObject<Pokemon>(json);
return output;
}
}
However I keep getting an exception that says "Cannot deserialize the current JSON array (e.g.[1,2,3]) into type 'Evolutions' because the type requires a JSON object..."
I found a lot of other questions asking the same exact thing, but I was confused with the top answers - sometimes the answer was to use JsonProperty, sometimes it was to use JsonConverter, without really an explanation on what all these meant. Do I need both?
Edit: sample json (call: http://pokeapi.co/api/v1/pokemon/1/)
{
"abilities": [
{
"name": "overgrow",
"resource_uri": "/api/v1/ability/1/"
},
{
"name": "chlorophyll",
"resource_uri": "/api/v1/ability/2/"
}
],
"attack": 49,
"catch_rate": 45,
"created": "2013-11-02T12:08:25.745455",
"defense": 49,
"egg_cycles": 21,
"egg_groups": [
{
"name": "Monster",
"resource_uri": "/api/v1/egg/1/"
},
{
"name": "Grass",
"resource_uri": "/api/v1/egg/8/"
}
],
"ev_yield": "1 Sp Atk",
"evolutions": {
"level": 16,
"method": "level up",
"resource_uri": "/api/v1/pokemon/2/",
"to": "Ivysaur"
},
"exp": 64,
"growth_rate": "ms",
"happiness": 70,
"height": "2'4",
"hp": 45,
"male_female_ratio": "87.5/12.5",
"modified": "2013-11-02T13:28:04.914889",
"moves": [
{
"learn_type": "other",
"name": "Tackle",
"resource_uri": "/api/v1/move/1/"
},
{
"learn_type": "other",
"name": "Growl",
"resource_uri": "/api/v1/move/2/"
},
{
"learn_type": "level up",
"level": 10,
"name": "Vine whip",
"resource_uri": "/api/v1/move/3/"
}
],
"name": "Bulbasaur",
"national_id": 1,
"resource_uri": "/api/v1/pokemon/4/",
"sp_atk": 65,
"sp_def": 65,
"species": "seed pokemon",
"speed": 45,
"total": 318,
"types": [
{
"name": "grass",
"resource_uri": "/api/v1/type/5/"
},
{
"name": "poison",
"resource_uri": "/api/v1/type/8/"
}
],
"weight": "15.2lbs"
}
Evolutions class:
public class Evolutions
{
public int level { get; set; }
public string method { get; set; }
public string resource_uri { get; set; }
public string to { get; set; }
}
I tried http://json2csharp.com/ with http://pokeapi.co/api/v1/pokemon/19/ and what I see is
public class RootObject
{
//...
public List<Evolution> evolutions { get; set; }
//...
}
This pretty mush is your Pokemon class. So you need to declare Evolutions as list.