# Custom Queries

If you need to perform an advanced SQL, you can write some scripts SQL and access them by REST. These scripts are templates where you can pass by URL and values to them.

***awesome\_folder/example\_of\_powerful.read.sql*****:**

```sql
SELECT * FROM table WHERE name = "{{.field1}}" OR name = "{{.field2}}"
```

**Get result:**

```
GET /_QUERIES/awesome_folder/example_of_powerful?field1=foo&field2=bar
```

**To activate it, you need to configure a location to scripts in your** `prest.toml` **like:**

```toml
[queries]
location = /path/to/queries/
```

### Scripts templates rules

In your scripts, the fields to replace have to look like: *field1 or field2 are examples.*

```sql
SELECT * FROM table WHERE name = "{{.field1}}" OR name = "{{.field2}}"
```

Script file must have a suffix based on http verb:

| HTTP Verb  | Suffix      |
| ---------- | ----------- |
| GET        | .read.sql   |
| POST       | .write.sql  |
| PUT, PATCH | .update.sql |
| DELETE     | .delete.sql |

In `queries.location`You need to have a folder for your scripts:

```shell
queries/
└── foo
    └── some_get.read.sql
    └── some_create.write.sql
    └── some_update.update.sql
    └── some_delete.delete.sql
└── bar
    └── some_get.read.sql
    └── some_create.write.sql
    └── some_update.update.sql
    └── some_delete.delete.sql

URLs to foo folder:

GET    /_QUERIES/foo/some_get?field1=bar
POST   /_QUERIES/foo/some_create?field1=bar
PUT    /_QUERIES/foo/some_update?field1=bar
PATCH  /_QUERIES/foo/some_update?field1=bar
DELETE /_QUERIES/foo/some_delete?field1=bar


URLs to bar folder:

GET    /_QUERIES/bar/some_get?field1=foo
POST   /_QUERIES/bar/some_create?field1=foo
PUT    /_QUERIES/bar/some_update?field1=foo
PATCH  /_QUERIES/bar/some_update?field1=foo
DELETE /_QUERIES/bar/some_delete?field1=foo
```

### Template data

You can access the query parameters of the incoming HTTP request using the `.` notation.

For instance, the following request:

```
GET    /_QUERIES/bar/some_get?field1=foo&field2=bar
```

Makes it available the fields `field1` and `field2` In the script:

```sql
{{.field1}}
{{.field2}}
```

You can also access the query headers of the incoming HTTP requests using the `.header` notation.

For instance, the following request:

```
GET    /_QUERIES/bar/some_get
X-UserId: am9obi5kb2VAYW5vbnltb3VzLmNvbQ
X-Application: prest
```

makes available the headers `X-UserId` and `X-Application` in the script:

```
{{index .header "X-UserId"}}
{{index .header "X-Application"}}
```

### Template functions

#### isSet

Return true if the param is set.

```sql
SELECT * FROM table
{{if isSet "field1"}}
WHERE name = "{{.field1}}"
{{end}}
```

#### defaultOrValue

Return param value or default value.

```sql
SELECT * FROM table WHERE name = '{{defaultOrValue "field1" "gopher"}}'
```

#### inFormat

If you need to format data for usage on a `IN ('option1', 'option2')` statement. You can use this with the field inside the format. Whenever passing multiple arguments to `inFormat` function, you must use multiple `field1` instances on the URL.

For example: I want to query the field `name` with options `Mary` and `John`.

```sql
-- URL will be equal to /_QUERIES/custom_query/query?name=Mary&name=John

SELECT * FROM names WHERE name IN {{inFormat "name"}}
```

**Future updates** will include the support of multiple strings split by `,` on the same instance of the field.

#### split

Splits a string into substrings separated by a delimiter

```sql
SELECT * FROM table WHERE
name IN ({{ range $index,$part := split 'test1,test2,test3' `,` }}{{if gt $index 0 }},{{end}}'{{$part}}'{{ end }})
```

#### limitOffset

Assemble `limit offset()` string with validation for non-allowed characters *parameters must be integer values*

```sql
SELECT * FROM table {{limitOffset "1" "10"}}
```

**generating the query:**

```sql
SELECT * FROM table LIMIT 10 OFFSET(1 - 1) * 10
```

*We recommend using the default pREST variables `_page` and `_page_size`:*

```sql
{{limitOffset ._page ._page_size}}
```

### Ready-made queries

*consultations ready to use prest*

* [Opps CMS](https://github.com/opps/prest-queries)