Add explicit field IDs to flatbuffer schemas (#148)

### Changelog
Added explicit field IDs to flatbuffer schemas.

### Docs

None

### Description

This allows the schemas to be compiled with `--require-explicit-ids`
turned on in `flatc`, which can be nice to help prevent people from
accidentally making breaking changes to flatbuffer schemas if they
choose to reorder fields (or insert new fields in the middle of the
schemas). Because of how flatc works with includes, if downstream users
want to use `--require-explicit-ids` on their own schemas that happen to
include foxglove schema types, they must update the foxglove schemas
that they use to include IDs.

.github/workflows/ci.yml

@@ -47,7 +47,7 @@ jobs:
 
       - name: Validate Flatbuffer definitions
         run: |
-          output=$(flatc --ts -o /dev/null ./schemas/flatbuffer/*.fbs)
+          output=$(flatc --require-explicit-ids --ts -o /dev/null ./schemas/flatbuffer/*.fbs)
           if [ -n "$output" ]; then
             echo "::error::Flatbuffer schema compilation had warnings or errors. Fix them to proceed:"
             echo "$output"

internal/generateFlatbufferSchema.test.ts

@@ -24,91 +24,91 @@ describe("generateFlatbuffers", () => {
       /// An example type
       table ExampleMessage {
         /// duration field
-        field_duration:Duration;
+        field_duration:Duration (id: 0);
 
         /// time field
-        field_time:Time;
+        field_time:Time (id: 1);
 
         /// boolean field
-        field_boolean:bool = true;
+        field_boolean:bool = true (id: 2);
 
         /// bytes field
-        field_bytes:[uint8];
+        field_bytes:[uint8] (id: 3);
 
         /// float64 field
-        field_float64:double = 1.0;
+        field_float64:double = 1.0 (id: 4);
 
         /// uint32 field
-        field_uint32:uint32 = 5;
+        field_uint32:uint32 = 5 (id: 5);
 
         /// string field
-        field_string:string = "string-type";
+        field_string:string = "string-type" (id: 6);
 
         /// duration array field
-        field_duration_array:[Duration];
+        field_duration_array:[Duration] (id: 7);
 
         /// time array field
-        field_time_array:[Time];
+        field_time_array:[Time] (id: 8);
 
         /// boolean array field
-        field_boolean_array:[bool];
+        field_boolean_array:[bool] (id: 9);
 
         /// bytes array field
-        field_bytes_array:[ByteVector];
+        field_bytes_array:[ByteVector] (id: 10);
 
         /// float64 array field
-        field_float64_array:[double];
+        field_float64_array:[double] (id: 11);
 
         /// uint32 array field
-        field_uint32_array:[uint32];
+        field_uint32_array:[uint32] (id: 12);
 
         /// string array field
-        field_string_array:[string];
+        field_string_array:[string] (id: 13);
 
         /// duration fixed-length array field
         /// length 3
-        field_duration_fixed_array:[Duration];
+        field_duration_fixed_array:[Duration] (id: 14);
 
         /// time fixed-length array field
         /// length 3
-        field_time_fixed_array:[Time];
+        field_time_fixed_array:[Time] (id: 15);
 
         /// boolean fixed-length array field
         /// length 3
-        field_boolean_fixed_array:[bool];
+        field_boolean_fixed_array:[bool] (id: 16);
 
         /// bytes fixed-length array field
         /// length 3
-        field_bytes_fixed_array:[ByteVector];
+        field_bytes_fixed_array:[ByteVector] (id: 17);
 
         /// float64 fixed-length array field
         /// length 3
-        field_float64_fixed_array:[double];
+        field_float64_fixed_array:[double] (id: 18);
 
         /// uint32 fixed-length array field
         /// length 3
-        field_uint32_fixed_array:[uint32];
+        field_uint32_fixed_array:[uint32] (id: 19);
 
         /// string fixed-length array field
         /// length 3
-        field_string_fixed_array:[string];
+        field_string_fixed_array:[string] (id: 20);
 
         /// An enum field
-        field_enum:ExampleEnum;
+        field_enum:ExampleEnum (id: 21);
 
         /// An enum array field
-        field_enum_array:[ExampleEnum];
+        field_enum_array:[ExampleEnum] (id: 22);
 
         /// A nested field
-        field_nested:foxglove.NestedMessage;
+        field_nested:foxglove.NestedMessage (id: 23);
 
         /// A nested array field
         /// With
         /// a
         /// very
         /// long
         /// description
-        field_nested_array:[foxglove.NestedMessage];
+        field_nested_array:[foxglove.NestedMessage] (id: 24);
       }
 
       root_type ExampleMessage;

internal/generateFlatbufferSchema.ts

@@ -6,7 +6,7 @@ namespace foxglove;
 
 /// Used for nesting byte vectors
 table ByteVector {
-  data:[uint8];
+  data:[uint8] (id: 0);
 }
 root_type ByteVector;
 `;
@@ -29,7 +29,7 @@ namespace foxglove;
 struct Duration {
   /// Signed seconds of the span of time. Must be from -315,576,000,000 to +315,576,000,000 inclusive.
   sec:int32;
-  /// if sec === 0 : -999,999,999 <= nsec <= +999,999,999 
+  /// if sec === 0 : -999,999,999 <= nsec <= +999,999,999
   /// otherwise sign of sec must match sign of nsec or be 0 and abs(nsec) <= 999,999,999
   nsec:int32;
 }
@@ -90,7 +90,7 @@ export function generateFlatbuffers(
       break;
     }
     case "message": {
-      const fields = schema.fields.map((field) => {
+      const fields = schema.fields.map((field, fieldId) => {
         const isArray = field.array != undefined;
 
         let type;
@@ -162,7 +162,7 @@ export function generateFlatbuffers(
           // convert field.name to lowercase for flatbuffer compilation compliance
         }  ${field.name.toLowerCase()}:${isArray ? `[${type}]` : type}${
           defaultValue ? ` = ${defaultValue}` : ""
-        };`;
+        } (id: ${fieldId});`;
       });
 
       definition = `${enumDefinitions.join("\n\n")}/// ${schema.description}\ntable ${

python/Makefile

@@ -12,6 +12,7 @@ endif
 generate-flatbuffer:
 	find foxglove-schemas-flatbuffer/foxglove_schemas_flatbuffer ! -name '__init__.py' -type f -exec rm -f {} +
 	pipenv run flatc \
+		--require-explicit-ids \
 		--python \
 		-o foxglove-schemas-flatbuffer/foxglove_schemas_flatbuffer \
 		../schemas/flatbuffer/*.fbs