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+
+## Code Structure
+
+Almost all of the rust code is either auto-generated or "glue" between the
+swagger API spec on one side and the SQL schema on the other.
+
+- `./migrations/*/up.sql`: SQL schema
+- `./src/database_schema.rs`: autogenerated per-table Diesel schemas
+- `./src/database_models.rs`: hand- and macro-generated Rust structs matching
+  Diesel schemas, and a small number of row-level helpers
+- `./src/database_entity_crud.rs`: "struct-relational-mapping"; trait
+  implementations of CRUD (create, read, update, delete) actions for each
+  entity model, hitting the database (and building on `database_model` structs)
+- `./src/api_server.rs`: one function for each API endpoint, with rust-style
+  arguments and return types. mostly calls in to `database_entity_crud`.
+- `./src/api_wrappers.rs`: hand- and macro-generated wrapper functions, one per
+  API endpoint, that map between API request and return types, and
+  rust-idiomatic request and return types (plus API models).
+- `./fatcat-api`: autogenerated API models and endpoint types/signatures
+- `../fatcat-openapi2.yaml`: 
+
+When deciding to use this structure, it wasn't expected that either
+`api_wrappers.rs` or `database_models.rs` would need to hand-maintained; both
+are verbose and implemented in a very mechanical fashion. The return type
+mapping in `api_wrappers` might be necessary, but `database_models.rs` in
+particular feels unnecessary; other projects have attempted to completely
+automate generation of this file, but it doesn't sound reliable. In particular,
+both regular "Row" (queriable) and "NewRow" (insertable) structs need to be
+defined.
+
+## Test Structure
+
+- `./tests/test_api_server.rs`: Iron (web framework) level raw HTTP JSON
+  request/response tests of API endpoints.
+
+## Updating Schemas
+
+Regenerate API schemas after editing the fatcat-openapi2 schema. This will, as
+a side-effect, also run `cargo fmt` on the whole project, so don't run it with
+your editor open!
+
+    cargo install cargo-swagger  # uses docker
+    ./codegen_openapi2.sh
+
+Update Rust database schema (after changing raw SQL schema):
+
+    diesel database reset
+    diesel print-schema > src/database_schema.rs
+
+Debug SQL schema errors (if diesel commands fail):
+
+    psql fatcat_test < migrations/2018-05-12-001226_init/up.sql
+
+## Direct API Interaction
+
+Creating entities via API:
+
+    http --json post localhost:9411/v0/container name=asdf issn=1234-5678