# erldb
[](https://github.com/erldb/erldb/actions)
ORM (Object-relational mapping) application implemented in Erlang. Still in very much beta :-)
# Configure erldb
Currently erldb supports two different backends; ets and mysql. We are hoping to support more.
# Writing models
This section will be written soon
## Basic structure
A model is defined by a basic set of attributes.
## Relations
There is currently two different relations in erldb;
`-relation(has, AMOUNT, MODEL_NAME).` - Defines a *one -> N* relation.
`-relation(belongs_to, MODEL_NAME).`
## Trigger functions
### Pre triggers
Pre-triggers can be defined by including the function `_pre_TRIGGERNAME/1` where the *triggername* can be one of: *update*, *lookup*, *delete* or *insert*.
### Post triggers
Post-triggers are defined almost the same as for pre-triggers. Just change *_pre_* to *_post*. Example: `_post_update/1`
## Compile the models
Right now you have to compile the models yourself. Please take a look at the *compilemodel*-script located in the *priv*-directory of this repository.
# Build
To build erldb use rebar3:
```
$ rebar3 compile
```
## Documentation
To generate documentation of erldb:
```
$ rebar3 edocs
```
# Try it out!!
Check the ``models/``-directory for example models. To compile the model tags.erl;
```
$ rebar3 shell
...compilation output...
1> erldb_compiler:compile("examples/tags.erl", [{includedir, "./include"}, {outdir, "."}]).
{ok,tags}
```
Now you can read the record definitions for each of the models within erlang:
```
2> rr("include/tags.hrl").
[tags]
3> A = #tags{}.
#tags{id = undefined,title = "Fancy title",text = undefined,
created = undefined}
4> B = A:uppercase_title().
"FANCY TITLE"
5> B:save()
{ok,#tags{author_id = undefined,id = id,
title = "FANCY TITLE",text = undefined,created = undefined}}
6> erldb:find(tags, []).
{ok,[#tags{author_id = undefined,id = id,
title = "FANCY TITLE",text = undefined,
created = undefined}]}
```
