How to serialize json in ELSA

[RekikMohamed]

I tried the sample code in the ELSA documentation to serialize a workflow from json.

using Elsa.Extensions;
using Elsa.Testing.Shared;
using Elsa.Workflows.Core.Contracts;
using Elsa.Workflows.Core.Models;
using Microsoft.Extensions.DependencyInjection;

// Setup service container.
var services = new ServiceCollection();

// Add Elsa services.
services.AddElsa();

// Build service container.
var serviceProvider = services.BuildServiceProvider();

// Populate registries. This is only necessary for applications  that are not using hosted services.
await serviceProvider.PopulateRegistriesAsync();

// Import a workflow from a JSON file.
var workflowJson = await File.ReadAllTextAsync("HelloWorld.json");

// Get a serializer to deserialize the workflow.
var serializer = serviceProvider.GetRequiredService<IActivitySerializer>();

// Deserialize the workflow.
var workflow = serializer.Deserialize<Workflow>(workflowJson);

// Resolve a workflow runner to run the workflow.
var workflowRunner = serviceProvider.GetRequiredService<IWorkflowRunner>();

// Run the workflow.
await workflowRunner.RunAsync(workflow);

The PopulateRegistriesAsync() method and some references do not exist, I get the following errors:

• Error CS0234 The type or namespace name 'Testing' does not exist in the namespace 'Elsa' (are you missing an assembly reference?)
• Error CS0234 The type or namespace name 'Core' does not exist in the namespace 'Elsa.Workflows' (are you missing an assembly reference?)
• Error CS0234 The type or namespace name 'Core' does not exist in the namespace 'Elsa.Workflows' (are you missing an assembly reference?)
• Error CS1061 'ServiceProvider' does not contain a definition for 'PopulateRegistriesAsync' and no accessible extension method 'PopulateRegistriesAsync' accepting a first argument of type 'ServiceProvider' could be found (are you missing a using directive or an assembly reference?)

When I remove the unfound references and run the application, I get the following exception stack in the deserialization:

at Elsa.Workflows.Services.ActivityFactory.ReadSyntheticInputs(ActivityDescriptor activityDescriptor, IActivity activity, JsonElement activityRoot, JsonSerializerOptions options)
at Elsa.Workflows.Services.ActivityFactory.Create(Type type, ActivityConstructorContext context)
at Elsa.Workflows.Serialization.Converters.ActivityJsonConverter.Read(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options)
at System.Text.Json.Serialization.JsonConverter1.TryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value, Boolean& isPopulatedValue) at System.Text.Json.Serialization.Metadata.JsonPropertyInfo1.ReadJsonAndSetMember(Object obj, ReadStack& state, Utf8JsonReader& reader)
at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value) at System.Text.Json.Serialization.JsonConverter1.TryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value, Boolean& isPopulatedValue)
at System.Text.Json.Serialization.JsonConverter1.ReadCore(Utf8JsonReader& reader, JsonSerializerOptions options, ReadStack& state) at System.Text.Json.JsonSerializer.ReadFromSpan[TValue](ReadOnlySpan1 utf8Json, JsonTypeInfo1 jsonTypeInfo, Nullable1 actualByteCount)
at System.Text.Json.JsonSerializer.ReadFromSpan[TValue](ReadOnlySpan1 json, JsonTypeInfo1 jsonTypeInfo)
at System.Text.Json.JsonSerializer.Deserialize[TValue](String json, JsonSerializerOptions options)
at Program.<

$>d__0.MoveNext() in D:\repos\WorkflowEngine\ElsaWorkflow\Program.cs:line 24

Any idea why is this happening?

[zhenlee-lt]

Any updates? I had the same issue. It's not working following the documentation.

[Green7]

You need to correct the "uses" section:

using Elsa.Testing.Shared;
using Elsa.Workflows;
using Elsa.Workflows.Activities;
using Microsoft.Extensions.DependencyInjection;