No coercion operator is defined between types 'System.IO.MemoryStream' and 'System.Nullable`1[System.Text.Json.JsonElement]' #2977
Comments
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I tried all Also tried changing |
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@taspeotis I think I'm going to need a minimal repro for this - can you please post one? Also, did this work for you in 7.0, and regress in 8.0? |
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I'm running in the same issue. I have a minimal repro here for you. I have my postgres up and running on localhost:5432 with user posgres.. My password is in environment variable PG_PASSWD. I created a database with name npgsql_jsonelement_issue_repro for testing. |
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@roji Yes it works in 7.x @UliPlabst Thanks for that, I have my own version as well using System.Text.Json;
using Microsoft.EntityFrameworkCore;
using Npgsql;
var dataSourceBuilder = new NpgsqlDataSourceBuilder
{
ConnectionStringBuilder =
{
Host = "localhost",
Database = "npgsql",
Username = "postgres",
Password = "postgres"
}
};
// JSON all the things...
dataSourceBuilder.EnableDynamicJson();
dataSourceBuilder.EnableRecordsAsTuples();
dataSourceBuilder.EnableUnmappedTypes();
await using var dataSource = dataSourceBuilder.Build();
var dbContextOptionsBuilder = new DbContextOptionsBuilder();
dbContextOptionsBuilder.UseNpgsql(dataSource);
await using var context = new NpgsqlContext(dbContextOptionsBuilder.Options);
await context.Database.EnsureDeletedAsync();
await context.Database.EnsureCreatedAsync();
await context.Database.ExecuteSqlRawAsync(
"""INSERT INTO "EntitiesWithNullableJsonElement" ("Id", "Json") VALUES (8, NULL);""");
await context.EntitiesWithNullableJsonElement.ToListAsync();
public sealed class NpgsqlContext(DbContextOptions options) : DbContext(options)
{
public DbSet<EntityWithNullableJsonElement> EntitiesWithNullableJsonElement { get; set; }
}
public sealed class EntityWithNullableJsonElement
{
public int Id { get; set; }
public JsonElement? Json { get; set; }
} |
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Here's a repro for the second error where I tried to change using System.Text.Json;
using Microsoft.EntityFrameworkCore;
using Npgsql;
await using var context = new NpgsqlContext();
public sealed class NpgsqlContext : DbContext
{
public DbSet<EntityWithNullableJsonElement> EntitiesWithNullableJsonElement { get; set; }
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
base.OnConfiguring(optionsBuilder);
var dataSourceBuilder = new NpgsqlDataSourceBuilder
{
ConnectionStringBuilder =
{
Host = "localhost",
Database = "npgsql",
Username = "postgres",
Password = "postgres"
}
};
// JSON all the things...
dataSourceBuilder.EnableDynamicJson();
dataSourceBuilder.EnableRecordsAsTuples();
dataSourceBuilder.EnableUnmappedTypes();
var dataSource = dataSourceBuilder.Build();
optionsBuilder.UseNpgsql(dataSource);
}
}
public sealed class EntityWithNullableJsonElement
{
public int Id { get; set; }
public JsonElement? Json { get; set; }
}
public sealed class EntityWithNullableJsonElement
{
public int Id { get; set; }
+ public JsonElement Json { get; set; }
- public JsonElement? Json { get; set; }
}
You'll get |
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I should clarify that the migration issue: I'm unsure if it works in Npgsql 7, I just stumbled upon it while trying to change the model to work around whatever has Npgsql 8 unhappy with But the initial issue, yes, Npgsql 7 handles it fine. |
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In my case I'm sure that it worked in Npgsql 7. |
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Thank you... It'll take me a few days to get around to it but I'll investigate. |
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Seeing the same problem after upgrading a project from npgsql 7 to 8 and trying to read a JsonElement? field. Changing the type of the field from JsonElement? to JsonElement makes the problem go away. Stack trace for reference: |
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Getting the same error. Also looks like it's working fine on 8.0.0-rc.2 and only breaks on 8.0.0 |
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I am probably completely wrong but I feel like |
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I just tried to apply a workaround based on @taspeotis suggestion of the underlying issue. I can now confirm that applying a custom IPropertyAddedConvention fixed the issue in my reproduction repository. Here's the code public class FixNpgsqlJsonElementHackConvention : IPropertyAddedConvention
{
private NpgsqlJsonTypeMapping? _jsonTypeMapping;
public void ProcessPropertyAdded(IConventionPropertyBuilder propertyBuilder, IConventionContext<IConventionPropertyBuilder> context)
{
var property = propertyBuilder.Metadata;
if (property.ClrType == typeof(JsonElement?) && property.GetColumnType() is null)
{
property.SetTypeMapping(_jsonTypeMapping ??= new NpgsqlJsonTypeMapping("jsonb", typeof(JsonElement?)));
}
}
}
//and in DbContext
public class AppDbContext: DbContext
{
//... omitted ....
protected override void ConfigureConventions(ModelConfigurationBuilder configurationBuilder)
{
configurationBuilder.Conventions.Add(_ => new FixNpgsqlJsonElementHackConvention());
}
}So as it appears with this workaround the issue is no longer blocking us from moving to .net8, hurray! I will merge the .net8 branch of my project tomorrow and see if the workaround works there as well but I am optimistic. |
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Fyi I confirmed today, the workaround is working for my project |
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Does anyone know if this might be causing this error (I'm using the workaround) and if theres any (simpleish) way around it? I'm trying to query: Where |
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The workaround provided by UliPlabst works if you select entity as is but it still fails if you map it to DTO. I have the following entity: With workaround it works when I query the whole entity with But it worked for 7.x and 8.0.0-rc.2. I've also tried to remove |
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Just ran into this in 8.0.5 (JsonElement? as a property - backed by a nullable jsonb colum - not supported), would be good to see PR #3008 merged |
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Also seeing this in 8.0.5 when it previously worked in 7.x versions. Would be great to see #3008 merged. |
I've upgraded to Npgsql 8 and started getting this:
In
Program.csI have added:But the error persists. I'll try and do a minimal reproducible example, but for now I believe it's this POCO causing grief:
Npgsql 7.x does not have this error.
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