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custom-queries.md

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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:

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:

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

Scripts templates rules

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

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.locationYou need to have a folder for your scripts:

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:

{{.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.

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

defaultOrValue

Return param value or default value.

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.

-- 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

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

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

generating the query:

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

We recommend using the default pREST variables _page and _page_size:

{{limitOffset ._page ._page_size}}

Ready-made queries

consultations ready to use prest