Json response gets truncated in web api using asp.net core

Question

I have a web api that returns a json object for me to use on my website. the problem is this:

[
{
    "installment": 1,
    "date": "03\/01\/2016",
    "amount": "27.28",
    "status": "\"01BI000657\""
},
{
    "installment": 2,
    "date": "04\/01\/2016",
    "amount": "49.25",
    "status": "\"01BI000699\""
},
{
    "installment": 3,
    "date": "05\/01\/2016",
    "amount": "56.31",
    "status": "\"01BI000745\""
},
{
    "installment": 4,
    "date": "06\/01\/2016",
    "amount": "53.43",
    "status": "\"01BI000811\""
},
{
    "installment": 5,
    "date": "07\/01\/2016",
    "amount": "60.52",
    "status": "\"01EI279932\""
},
{
    "installment": 6,
    "date": "08\/01\/2016",
    "amount": "57.95",
    "status": "\"01BI000934\""
},
{
    "installment": 7,
    "date": "09\/01\/2016",
    "amount": "60.24",
    "status": "\"01BI001015\""
},
{
    "installment": 8,
    "date": "10\/01\/2016",
    "amount": "67.36",
    "status": "\"01EI298127\""
},
{
    "installment": 9,
    "date": "11\/01\/2016",
    "amount": "65.30",
    "status": "\"01BI001185\""
},
{
    "installment": 10,
    "date": "12\/01\/2016",
    "amount": "72.44",
    "status": "\"01BI001277\""
},
{
    "installment": 11,
    "date": "01\/01\/2017",
    "amount": "70.75",
    "status": "\"01BI001380\""
},
{
    "installment": 12,
    "date": "02\/01\/2017",
    "amount": "73.55",
    "status": "\"01BI001486\""
},
{
    "installment": 13,
    "date": "03\/01\/2017",
    "amount": "89.28",
    "status": "\"01BI001567\""
},
{
    "installment": 14,
    "date": "04\/01\/2017",
    "amount": "80.00",
    "status": "\"01BI001691\""
},
{
    "installment": 15,
    "date": "05\/01\/2017",
    "amount": "87.23",
    "status": "\"01BI001822\""
},
{
    "installment": 16,
    "date": "06\/01\/2017",
    "amount": "86.63",
    "status": "\"01BI002011\""
},
{
    "installment": 17,
    "date": "07\/01\/2017",
    "amount": "93.89",
    "status": "\"01BI002172\""
},
{
    "installment": 18,
    "date": "08\/01\/2017",
    "amount": "93.78",
    "status": "\"01BI002369\""
},
{
    "installment": 19,
    "date": "09\/01\/2017",
    "amount": "97.49",
    "status": "\"\""
},
{
    "installment": 20,
    "date": "10\/01\/2017",
    "amount": "104.81",
    "status": "\"\""
},
{
    "installment": 21,
    "date": "11\/01\/2017",
    "amount": "105.50",
    "status": "\"\""
},
{
    "installment": 22,
    "date": "12\/01\/2017",
    "amount": "112.87",
    "status": "\"\""
},
{
    "installment": 23,
    "date": "01\/01\/2018",
    "amount": "114.15",
    "status": "\"\""
},
{
    "installment": 24,
    "date": "02\/01\/2018",
    "amount": "118.67",
    "status": "\"\""
},
{
    "installment": 25,
    "date": "03\/01\/2018",
    "amount": "131.57",
    "status": "\"\""
},
{"ins

as you can see it gets truncated, it weights 20kb, string length is 2033, so I wanted to know if there is a way to increase the max size of the response somehow. I tried the MaxJsonLength inside the web.config but it is not working, might be because of the .net core aspect so I am kinda lost, why it is getting truncated.

IngoB · Accepted Answer · 2017-11-08 18:39:32Z

24

I don't know why the json response gets truncated at some point, but in my case (ASP.NET Core 2.0) I had to tell Newtonsoft.Json to ignore reference loops like so:

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc()
        .AddJsonOptions(
            options => options.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore
        );
}

answered Nov 8, 2017 at 18:39

IngoB

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3 Comments

FailedUnitTest Over a year ago

This to me, is a sign of code smell. Why is there a ReferenceLoop in this model? Is this a good case for ViewModel + AutoMapper?

Sam Over a year ago

I ran into this today and this fixed my issue. I'm shocked more people don't run into this. Thanks for the tip!

Dvd Franco Over a year ago

best answer!! It solves the problem, indeed!

Ian Mercer · Accepted Answer · 2019-08-08 14:31:44Z

4

One reason this can happen is if an error happens while serializing the object to JSON. For example a field marked as required that is not present in the data can cause this. The output simply stops and no exception is reported in this case.

Check that you can serialize the json object using JSonConvert.SerializeObject() before returning it and fix up any issues.

answered Aug 8, 2019 at 14:31

Ian Mercer

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Comments

Anov · Accepted Answer · 2019-01-03 19:22:11Z

1

The truncation at 2033 makes me think that you're only grabbing the first piece of what SQL Server is returning. You need to concatenate all the results together, e.g.:

var queryWithForJson = "SELECT ... FOR JSON";
var conn = new SqlConnection("<connection string>");
var cmd = new SqlCommand(queryWithForJson, conn);
conn.Open();
var jsonResult = new StringBuilder();
var reader = cmd.ExecuteReader();
if (!reader.HasRows)
{
    jsonResult.Append("[]");
}
else
{
    while (reader.Read())
    {
        jsonResult.Append(reader.GetValue(0).ToString());
    }
}

answered Jan 3, 2019 at 19:22

Anov

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Comments

Dan Narsavage · Accepted Answer · 2018-12-24 23:00:02Z

For anyone who might end up here after seeing this when serving spatial types . . .

@IngoB 's answer made the issue go away, but then (along with the code-smell comment from @FailedUnitTest ringing true) there was a giant wad of stuff I wasn't expecting in the JSON for my simple Point. Setting ReferenceLoopHandling to Serialize and debugging allowed me to see details about what was happening, and eventually I ended up here.

Synopsis:

Install the NetTopologySuite.IO.GeoJSON package

Throw something like this in ConfigureServices():

services.AddMvc(options =>
    {
        options.ModelMetadataDetailsProviders.Add(new SuppressChildValidationMetadataProvider(typeof(Point)));
    })
    .AddJsonOptions(options =>
    {
        foreach (var converter in GeoJsonSerializer.Create(new GeometryFactory(new PrecisionModel(), 4326)).Converters)
        {
            options.SerializerSettings.Converters.Add(converter);
        }
    });

V. Benavides · Accepted Answer · 2018-12-26 11:36:25Z

0

I know this is a bit late and might be answered already by others in other posts, but I fixed this by serializing with a reader the sql query and returning the object which gets transformed instantly into JSON without returning the query as JSON from the start.

answered Dec 26, 2018 at 11:36

V. Benavides

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Comments

HappyTown · Accepted Answer · 2021-03-25 21:02:40Z

0

My scenario was

.NET Core 3.1,
Newtonsoft JSON for serialization, and
a custom middleware to change the response body (response wrapping).

The solution described at JSON response breaks in ASP.NET Core 3.1 Web API with custom response wrapper worked for me.

Also, https://github.com/dotnet/core/issues/1240 has some useful discussion.

answered Mar 25, 2021 at 21:02

HappyTown

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