Add support for collection of oracles to chains endpoint (#210)

- Breaking Change /api/v1/chains: each chain is now allowed to have multiple gas price configurations (resulting in a collection instead of a single object of fixed and oracle gas prices).
- The new GasPrice for each chain is now ranked – a lower value means that it'd show up higher on the list (eg.: rank 1 > rank 100)
- The new GasPrice collection is allowed to be empty – this is not only to reduce complexity but also because the current relationship between GasPrice <> Chain means that a Chain needs to exist first before assigning a GasPrice to it.

src/chains/admin.py

@@ -1,6 +1,6 @@
 from django.contrib import admin
 
-from .models import Chain
+from .models import Chain, GasPrice
 
 
 @admin.register(Chain)
@@ -17,3 +17,15 @@ class ChainAdmin(admin.ModelAdmin):
         "relevance",
         "name",
     )
+
+
+@admin.register(GasPrice)
+class GasPrice(admin.ModelAdmin):
+    list_display = (
+        "chain_id",
+        "oracle_uri",
+        "fixed_wei_value",
+        "rank",
+    )
+    search_fields = ("chain_id", "oracle_uri")
+    ordering = ("rank",)

src/chains/migrations/0023_create_gas_price_model.py

@@ -0,0 +1,74 @@
+# Generated by Django 3.2.6 on 2021-09-01 12:38
+
+import django.db.models.deletion
+import gnosis.eth.django.models
+from django.db import migrations, models
+
+
+def copy_gas_prices(apps, schema_editor):
+    GasPrice = apps.get_model("chains", "GasPrice")
+    Chain = apps.get_model("chains", "Chain")
+
+    GasPrice.objects.bulk_create(
+        GasPrice(
+            chain=chain,
+            oracle_uri=chain.gas_price_oracle_uri,
+            oracle_parameter=chain.gas_price_oracle_parameter,
+            gwei_factor=chain.gas_price_oracle_gwei_factor,
+            fixed_wei_value=chain.gas_price_fixed_wei,
+        )
+        for chain in Chain.objects.all()
+    )
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("chains", "0022_remove_chain_block_explorer_uri"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="GasPrice",
+            fields=[
+                (
+                    "id",
+                    models.BigAutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+                ("oracle_uri", models.URLField(blank=True, null=True)),
+                (
+                    "oracle_parameter",
+                    models.CharField(blank=True, max_length=255, null=True),
+                ),
+                (
+                    "gwei_factor",
+                    models.DecimalField(
+                        decimal_places=9,
+                        default=1,
+                        help_text="Factor required to reach the Gwei unit",
+                        max_digits=19,
+                        verbose_name="Gwei multiplier factor",
+                    ),
+                ),
+                (
+                    "fixed_wei_value",
+                    gnosis.eth.django.models.Uint256Field(
+                        blank=True, null=True, verbose_name="Fixed gas price (wei)"
+                    ),
+                ),
+                ("rank", models.SmallIntegerField(default=100)),
+                (
+                    "chain",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE, to="chains.chain"
+                    ),
+                ),
+            ],
+        ),
+        # noop for backwards because it will be handled by the backwards of CreateModel (ie.: destroying the model)
+        migrations.RunPython(copy_gas_prices, migrations.RunPython.noop),
+    ]

src/chains/migrations/0024_remove_gas_price_fields.py

@@ -0,0 +1,28 @@
+# Generated by Django 3.2.6 on 2021-09-01 12:38
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("chains", "0023_create_gas_price_model"),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name="chain",
+            name="gas_price_fixed_wei",
+        ),
+        migrations.RemoveField(
+            model_name="chain",
+            name="gas_price_oracle_gwei_factor",
+        ),
+        migrations.RemoveField(
+            model_name="chain",
+            name="gas_price_oracle_parameter",
+        ),
+        migrations.RemoveField(
+            model_name="chain",
+            name="gas_price_oracle_uri",
+        ),
+    ]

src/chains/models.py

@@ -57,39 +57,45 @@ class RpcAuthentication(models.TextChoices):
         help_text="Please use the following format: <em>#RRGGBB</em>.",
     )
     ens_registry_address = EthereumAddressField(null=True, blank=True)
-    gas_price_oracle_uri = models.URLField(blank=True, null=True)
-    gas_price_oracle_parameter = models.CharField(blank=True, null=True, max_length=255)
-    gas_price_oracle_gwei_factor = models.DecimalField(
+
+    recommended_master_copy_version = models.CharField(
+        max_length=255, validators=[sem_ver_validator]
+    )
+
+    def __str__(self):
+        return f"{self.name} | chain_id={self.id}"
+
+
+class GasPrice(models.Model):
+    chain = models.ForeignKey(Chain, on_delete=models.CASCADE)
+    oracle_uri = models.URLField(blank=True, null=True)
+    oracle_parameter = models.CharField(blank=True, null=True, max_length=255)
+    gwei_factor = models.DecimalField(
         default=1,
         max_digits=19,
         decimal_places=9,
         verbose_name="Gwei multiplier factor",
         help_text="Factor required to reach the Gwei unit",
     )
-    gas_price_fixed_wei = Uint256Field(
+    fixed_wei_value = Uint256Field(
         verbose_name="Fixed gas price (wei)", blank=True, null=True
     )
-    recommended_master_copy_version = models.CharField(
-        max_length=255, validators=[sem_ver_validator]
-    )
+    rank = models.SmallIntegerField(
+        default=100
+    )  # A lower number will indicate higher ranking
+
+    def __str__(self):
+        return f"Chain = {self.chain.id} | uri={self.oracle_uri} | fixed_wei_value={self.fixed_wei_value}"
 
     def clean(self):
-        if (self.gas_price_fixed_wei is not None) == (
-            self.gas_price_oracle_uri is not None
-        ):
+        if (self.fixed_wei_value is not None) == (self.oracle_uri is not None):
             raise ValidationError(
                 {
-                    "gas_price_oracle_uri": "An oracle uri or fixed gas price should be provided (but not both)",
-                    "gas_price_fixed_wei": "An oracle uri or fixed gas price should be provided (but not both)",
+                    "oracle_uri": "An oracle uri or fixed gas price should be provided (but not both)",
+                    "fixed_wei_value": "An oracle uri or fixed gas price should be provided (but not both)",
                 }
             )
-        if (
-            self.gas_price_oracle_uri is not None
-            and self.gas_price_oracle_parameter is None
-        ):
+        if self.oracle_uri is not None and self.oracle_parameter is None:
             raise ValidationError(
-                {"gas_price_oracle_parameter": "The oracle parameter should be set"}
+                {"oracle_parameter": "The oracle parameter should be set"}
             )
-
-    def __str__(self):
-        return f"{self.name} | chain_id={self.id}"

src/chains/serializers.py

@@ -10,16 +10,26 @@
 
 class GasPriceOracleSerializer(serializers.Serializer):
     type = serializers.ReadOnlyField(default="oracle")
-    uri = serializers.URLField(source="gas_price_oracle_uri")
-    gas_parameter = serializers.CharField(source="gas_price_oracle_parameter")
-    gwei_factor = serializers.DecimalField(
-        source="gas_price_oracle_gwei_factor", max_digits=19, decimal_places=9
-    )
+    uri = serializers.URLField(source="oracle_uri")
+    gas_parameter = serializers.CharField(source="oracle_parameter")
+    gwei_factor = serializers.DecimalField(max_digits=19, decimal_places=9)
 
 
 class GasPriceFixedSerializer(serializers.Serializer):
     type = serializers.ReadOnlyField(default="fixed")
-    wei_value = serializers.CharField(source="gas_price_fixed_wei")
+    wei_value = serializers.CharField(source="fixed_wei_value")
+
+
+class GasPriceSerializer(serializers.Serializer):
+    def to_representation(self, instance):
+        if instance.oracle_uri and instance.fixed_wei_value is None:
+            return GasPriceOracleSerializer(instance).data
+        elif instance.fixed_wei_value and instance.oracle_uri is None:
+            return GasPriceFixedSerializer(instance).data
+        else:
+            raise APIException(
+                f"The gas price oracle or a fixed gas price was not provided for chain {instance.chain}"
+            )
 
 
 class ThemeSerializer(serializers.Serializer):
@@ -123,13 +133,7 @@ def get_rpc_uri(obj):
     def get_block_explorer_uri_template(obj):
         return BlockExplorerUriTemplateSerializer(obj).data
 
-    @staticmethod
-    def get_gas_price(obj):
-        if obj.gas_price_oracle_uri and obj.gas_price_fixed_wei is None:
-            return GasPriceOracleSerializer(obj).data
-        elif obj.gas_price_fixed_wei and obj.gas_price_oracle_uri is None:
-            return GasPriceFixedSerializer(obj).data
-        else:
-            raise APIException(
-                f"The gas price oracle or a fixed gas price was not provided for chain {obj.id}"
-            )
+    @swagger_serializer_method(serializer_or_field=GasPriceSerializer)
+    def get_gas_price(self, instance):
+        ranked_gas_prices = instance.gasprice_set.all().order_by("rank")
+        return GasPriceSerializer(ranked_gas_prices, many=True).data

src/chains/tests/factories.py

@@ -4,7 +4,7 @@
 import web3
 from factory.django import DjangoModelFactory
 
-from ..models import Chain
+from ..models import Chain, GasPrice
 
 
 class ChainFactory(DjangoModelFactory):
@@ -31,13 +31,21 @@ class Meta:
     transaction_service_uri = factory.Faker("url")
     theme_text_color = factory.Faker("hex_color")
     theme_background_color = factory.Faker("hex_color")
-    gas_price_oracle_uri = None
-    gas_price_oracle_parameter = None
     ens_registry_address = factory.LazyAttribute(
         lambda o: web3.Account.create().address
     )
-    gas_price_oracle_gwei_factor = factory.Faker(
+    recommended_master_copy_version = "1.3.0"
+
+
+class GasPriceFactory(DjangoModelFactory):
+    class Meta:
+        model = GasPrice
+
+    chain = factory.SubFactory(ChainFactory)
+    oracle_uri = None
+    oracle_parameter = None
+    gwei_factor = factory.Faker(
         "pydecimal", positive=True, min_value=1, max_value=1_000_000_000, right_digits=9
     )
-    gas_price_fixed_wei = factory.Faker("pyint")
-    recommended_master_copy_version = "1.3.0"
+    fixed_wei_value = factory.Faker("pyint")
+    rank = factory.Faker("pyint")