data_schema

# Changelog for version 0.2.x

## 0.2.5

### Bug fix

Fix schema validations and error message.

We were not allowing valid schema syntax for an inline schema (ie a
runtime schema that is provided at compile time), and our error message
was wrong.

Now we correctly allow:

```elixir
has_many: {:dep, "./Dep", {%{}, @place_schema}},
has_one: {:arrival, "./Arrival", {%{}, @place_schema}},
```

And similar.

## 0.2.4

### Feature

Enables Runtime schemas and parsing to a bare map. Check out the provided docs and livebook for more info!

## 0.2.3

### Bug fix

Ensures we call `Code.ensure_loaded?` before checking if function is exported. This was causing problems when running tests.

## 0.2.2

### Bug fix

We were not creating the nested errors correctly for has_many and has_one, now we do.
We also were removing `nil`s when they were allowed for `:list_of`, we now don't.

## 0.2.1

### Bug fix

Previously we could not use a `:list_of` field on an inline `:aggregate` field. This fixes that.

## 0.2.0

This represents a major change with lots of functionality re-thought an simplified. I would be highly surprised if anyone is even using this library at this point but it is good practice to mention it is a breaking change.

### Breaking Changes

- `to_struct!/2` has been removed. `to_struct/2` now expects casting functions to return okay / error tuples.
- Cast behaviour added and enforces that cast fns return okay / error tuples
- `data_schema/2` has been removed. Instead you now supply a data_accessor via a module attribute on the schema.
- `to_struct/2` now returns an `{:error, DataSchema.Error.t()}` at the first time an error is encountered. If the field that failed is nested the error will be a nested error that points to the field that failed. This makes it easy to see what the error was, but might make it harder to traverse errors later. We will see.
- `DataSchema.AccessBehaviour` has changed to remove the `aggregate` function. Because of the change in how aggregates work this is now no longer needed here.
- Aggregate fields now either specify a nested schema or supply fields (effectively a schemaless schema). This means we can have aggregates which include lists of things in the aggregation.
- `list_of` has changed a little in that you should not really use `list_of` for a list of nested schemas. You still can but it leads to possible problems like having two sets of options sent to the to_struct function making it unclear what would happen.

### Enhancements

So many good things including better docs and the like. But:

- Adds a `has_many` field. This is in addition to the `list_of` field and there are good reasons for having them all which I will explain in some docs soon.
- Adds an `DataSchema.Erros` struct to communicate errors.
- More and better schema validations on schema create - we raise some nice errors in the case of misconfigured schemas.

## 0.0.2

### Enhancement

Much better docs and some ex_doc niceties added.

### Breaking Change

* This changes the name of `to_struct` to `to_struct!`
* adds a `to_struct` function that lets us return error tuples from casting functions and have the casting halt and return the error.

## 0.0.1

### Enhancement

Implements a first stab at data schemas. Check the docs for how they work.