Check if null before unmarshalling (#290)

* Check if null before unmarshalling

Checks if an attribute is null before attempting to unmarshal it.

Closes #289

* Use a helper for safely unamrshalling

Uses a helper method for this so we have it handy next time we need to
unmarshal an attribute that could be null.

internal/provider/helpers/marshal.go

@@ -0,0 +1,19 @@
+package helpers
+
+import (
+	"github.com/hashicorp/terraform-plugin-framework-jsontypes/jsontypes"
+	"github.com/hashicorp/terraform-plugin-framework/diag"
+)
+
+// SafeUnmarshal is a helper function for safely unmarshalling a JSON object by checking if
+// it is null before attempting to unmarshal it. This should always be used for optional attributes.
+func SafeUnmarshal(attribute jsontypes.Normalized) (map[string]interface{}, diag.Diagnostics) {
+	var diags diag.Diagnostics
+
+	result := map[string]interface{}{}
+	if !attribute.IsNull() {
+		diags = attribute.Unmarshal(&result)
+	}
+
+	return result, diags
+}

internal/provider/resources/deployment.go

@@ -307,20 +307,20 @@ func (r *DeploymentResource) Create(ctx context.Context, req resource.CreateRequ
 		return
 	}
 
-	var parameters map[string]interface{}
-	resp.Diagnostics.Append(plan.Parameters.Unmarshal(&parameters)...)
+	parameters, diags := helpers.SafeUnmarshal(plan.Parameters)
+	resp.Diagnostics.Append(diags...)
 	if resp.Diagnostics.HasError() {
 		return
 	}
 
-	var jobVariables map[string]interface{}
-	resp.Diagnostics.Append(plan.JobVariables.Unmarshal(&jobVariables)...)
+	jobVariables, diags := helpers.SafeUnmarshal(plan.JobVariables)
+	resp.Diagnostics.Append(diags...)
 	if resp.Diagnostics.HasError() {
 		return
 	}
 
-	var parameterOpenAPISchema map[string]interface{}
-	resp.Diagnostics.Append(plan.ParameterOpenAPISchema.Unmarshal(&parameterOpenAPISchema)...)
+	parameterOpenAPISchema, diags := helpers.SafeUnmarshal(plan.ParameterOpenAPISchema)
+	resp.Diagnostics.Append(diags...)
 	if resp.Diagnostics.HasError() {
 		return
 	}
@@ -473,15 +473,19 @@ func (r *DeploymentResource) Update(ctx context.Context, req resource.UpdateRequ
 	}
 
 	var parameters map[string]interface{}
-	resp.Diagnostics.Append(model.Parameters.Unmarshal(&parameters)...)
-	if resp.Diagnostics.HasError() {
-		return
+	if !model.Parameters.IsNull() {
+		resp.Diagnostics.Append(model.Parameters.Unmarshal(&parameters)...)
+		if resp.Diagnostics.HasError() {
+			return
+		}
 	}
 
 	var jobVariables map[string]interface{}
-	resp.Diagnostics.Append(model.JobVariables.Unmarshal(&jobVariables)...)
-	if resp.Diagnostics.HasError() {
-		return
+	if !model.JobVariables.IsNull() {
+		resp.Diagnostics.Append(model.JobVariables.Unmarshal(&jobVariables)...)
+		if resp.Diagnostics.HasError() {
+			return
+		}
 	}
 
 	payload := api.DeploymentUpdate{

internal/provider/resources/work_pool.go

@@ -198,8 +198,8 @@ func (r *WorkPoolResource) Create(ctx context.Context, req resource.CreateReques
 		return
 	}
 
-	baseJobTemplate := map[string]interface{}{}
-	resp.Diagnostics.Append(plan.BaseJobTemplate.Unmarshal(&baseJobTemplate)...)
+	baseJobTemplate, diag := helpers.SafeUnmarshal(plan.BaseJobTemplate)
+	resp.Diagnostics.Append(diag...)
 	if resp.Diagnostics.HasError() {
 		return
 	}
@@ -277,8 +277,8 @@ func (r *WorkPoolResource) Update(ctx context.Context, req resource.UpdateReques
 		return
 	}
 
-	baseJobTemplate := map[string]interface{}{}
-	resp.Diagnostics.Append(plan.BaseJobTemplate.Unmarshal(&baseJobTemplate)...)
+	baseJobTemplate, diag := helpers.SafeUnmarshal(plan.BaseJobTemplate)
+	resp.Diagnostics.Append(diag...)
 	if resp.Diagnostics.HasError() {
 		return
 	}