# JSRelationItem

## Overview

`JSRelationItem` represents a single criterion within a relation in the solution model. It defines how columns from the primary and foreign data sources are connected, enabling precise relationship definitions for queries and data operations. ## Functionality

JSRelationItem provides constants such as `LITERAL_PREFIX` to enable the use of literals in relation definitions. Properties like `foreignColumnName`, `primaryDataProviderID`, and `operator` allow customization of the relationship criteria. Supported operators include `=`, `!=`, `<`, `>`, `like`, and more, enabling a wide range of comparisons and queries between data sources.

Methods like `getComment` and `getUUID` assist in retrieving metadata about the relation item, such as a unique identifier or comments. These utilities enhance the traceability and documentation of relation definitions in complex solution models.

### Example

A relation item can be configured to specify relationships like:

* Linking a column from the primary table to a foreign table.
* Using literals or specific operators to define advanced criteria.

For more details, please refer to the [Relation item](https://docs.servoy.com/reference/servoycore/object-model/solution/relation/relationitem) section of this documentation.

## Constants Summarized

| Type                                                                         | Name                               | Summary                                                     |
| ---------------------------------------------------------------------------- | ---------------------------------- | ----------------------------------------------------------- |
| [String](https://docs.servoy.com/reference/servoycore/dev-api/js-lib/string) | [LITERAL\_PREFIX](#literal_prefix) | Constant for using literals in solution model in relations. |

## Properties Summarized

| Type                                                                         | Name                                            | Summary                                                                                             |
| ---------------------------------------------------------------------------- | ----------------------------------------------- | --------------------------------------------------------------------------------------------------- |
| [String](https://docs.servoy.com/reference/servoycore/dev-api/js-lib/string) | [foreignColumnName](#foreigncolumnname)         | The name of the column from the destination table that this relation item is based on.              |
| [String](https://docs.servoy.com/reference/servoycore/dev-api/js-lib/string) | [operator](#operator)                           | The operator that defines the relationship between the primary dataprovider and the foreign column. |
| [String](https://docs.servoy.com/reference/servoycore/dev-api/js-lib/string) | [primaryDataProviderID](#primarydataproviderid) | The name of the column from the source table that this relation item is based on.                   |
| [Object](https://docs.servoy.com/reference/servoycore/dev-api/js-lib/object) | [primaryLiteral](#primaryliteral)               | Get the literal.                                                                                    |

## Methods Summarized

| Type                                                                          | Name                        | Summary                                |
| ----------------------------------------------------------------------------- | --------------------------- | -------------------------------------- |
| [String](https://docs.servoy.com/reference/servoycore/dev-api/js-lib/string)  | [getComment()](#getcomment) | Returns the comment of this component. |
| [UUID](https://docs.servoy.com/reference/servoycore/dev-api/application/uuid) | [getUUID()](#getuuid)       | Returns the UUID of this component.    |

## Constants Detailed

### LITERAL\_PREFIX

Constant for using literals in solution model in relations.\
Strings must be passed as quoted value to make a distinction between string '5' and number 5.

**Type**\
[String](https://docs.servoy.com/reference/servoycore/dev-api/js-lib/string)

**Sample**

```js
relation.newRelationItem(JSRelationItem.LITERAL_PREFIX + "'hello'",'=', 'mytextfield');
```

## Properties Detailed

### foreignColumnName

The name of the column from the destination table that this relation item is based on.

**Type**\
[String](https://docs.servoy.com/reference/servoycore/dev-api/js-lib/string)

**Sample**

```js
var relation = solutionModel.newRelation('parentToChild', 'db:/example_data/parent_table', 'db:/example_data/child_table', JSRelation.INNER_JOIN);
var criteria = relation.newRelationItem('parent_table_id', '=', 'child_table_parent_id');
criteria.primaryDataProviderID = 'parent_table_text';
criteria.foreignColumnName = 'child_table_text';
criteria.operator = '<';
```

### operator

The operator that defines the relationship between the primary dataprovider and the foreign column. Each key pair expression is evaluated using a single operator. Certain operators are only applicable to certain data types. Below is a list of all available operators and the data types for which they are applicable.

| Operator | Description                         | Data Types                                            |
| -------- | ----------------------------------- | ----------------------------------------------------- |
| =        | Equals                              | Text, Integer, Number, Datetime, UUID, Array (in)     |
| >        | Greater Than                        | Text, Integer, Number, Datetime                       |
| <        | Less Than                           | Text, Integer, Number, Datetime                       |
| >=       | Greater Than or Equal To            | Text, Integer, Number, Datetime                       |
| <=       | Less Than or Equal To               | Text, Integer, Number, Datetime                       |
| !=       | NOT Equal To                        | Text, Integer, Number, Datetime, UUID, Array (not in) |
| like     | SQL Like use with '%' wildcards     | Text                                                  |
| not like | SQL Not Like use with '%' wildcards | Text                                                  |

**Type**\
[String](https://docs.servoy.com/reference/servoycore/dev-api/js-lib/string)

**Sample**

```js
var relation = solutionModel.newRelation('parentToChild', 'db:/example_data/parent_table', 'db:/example_data/child_table', JSRelation.INNER_JOIN);
var criteria = relation.newRelationItem('parent_table_id', '=', 'child_table_parent_id');
criteria.primaryDataProviderID = 'parent_table_text';
criteria.foreignColumnName = 'child_table_text';
criteria.operator = '<';
```

### primaryDataProviderID

The name of the column from the source table that this relation item is based on.

**Type**\
[String](https://docs.servoy.com/reference/servoycore/dev-api/js-lib/string)

**Sample**

```js
var relation = solutionModel.newRelation('parentToChild', 'db:/example_data/parent_table', 'db:/example_data/child_table', JSRelation.INNER_JOIN);
var criteria = relation.newRelationItem('parent_table_id', '=', 'child_table_parent_id');
criteria.primaryDataProviderID = 'parent_table_text';
criteria.foreignColumnName = 'child_table_text';
criteria.operator = '<';
```

### primaryLiteral

Get the literal.

**Type**\
[Object](https://docs.servoy.com/reference/servoycore/dev-api/js-lib/object)

**Sample**

```js
var relation = solutionModel.newRelation('parentToChild', 'db:/example_data/parent_table', 'db:/example_data/child_table', JSRelation.INNER_JOIN);
var criteria = relation.newRelationItem(JSRelationItem.LITERAL_PREFIX + "'hello'",'=', 'myTextField');
criteria.primaryLiteral = 'literal_text';
//criteria.primaryLiteral = number;
var primaryLiteral = criteria.primaryLiteral;
```

## Methods Detailed

### getComment()

Returns the comment of this component.

**Returns:** [String](https://docs.servoy.com/reference/servoycore/dev-api/js-lib/string) the comment associated with this component.

**Sample**

```js
var comment = solutionModel.getForm("my_form").getButton("my_button").getComment();
application.output(comment);
```

### getUUID()

Returns the UUID of this component.

**Returns:** [UUID](https://docs.servoy.com/reference/servoycore/dev-api/application/uuid) the UUID of this component.

**Sample**

```js
var button_uuid = solutionModel.getForm("my_form").getButton("my_button").getUUID();
application.output(button_uuid.toString());
```

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