@emerbrito/expression-builder NPM

Angular Material Expression Builder

Expression Builder

A simple to use expression builder created with Angular Material components.
Outputs a data structure (JSON) representing the expression which you can use to build queries and filters.

npm install @emerbrito/expression-builder

Getting Started

The first step is to configure the fields available to the end user when building expressions.
A field is defined by the Field interface:

export interface Field {
    label: string,
    name: string,    
    type: FieldType,
    values?: OptionValue[]
}

Field type is used for input validation and to render the appropriated control.
Property values is optional. When specified a dropdown with the options will be rendered indifferent of the field type, which still applies to validation.

Bellow is an example of some field definitions:

const fields = [
    {
        name: "firstName",
        label: "First Name",
        type: FieldType.Text
    },
    {
        "name": "married",
        "label": "Married",
        "type": FieldType.Boolean,
        "values": [
            {
                "value": "true ",
                "label ": "Yes"
            },
            {
                "value": "false ",
                "label ": "No"
            }
        ]
    }
];

Use the component's input property to pass the field configurations:

<expression-builder 
    [fields]="fields" 
    [data]="exp" 
    (valuechange)="changeHandler($event)">
</expression-builder>

Component properties

@Input() fields

Type: Field[]
Required. Array containing the fields available trough the expression builder.

@Input() data

Type: QueryExpression Optional.
Initial expression.

@Output() valuechange

Argument: ExpressionChangeEvent
Fires every time the expression changes. Contains the current expression and a flag indicating whether or not it is in a valid state.

Sample Expression

Bellow is a sample of the expression produce by the component:

{
  "operator": "and",
  "rules": [
    {
      "fieldName": "voter",
      "condition": "eq",
      "value": "true"
    },
    {
      "operator": "or",
      "rules": [
        {
          "fieldName": "married",
          "condition": "eq",
          "value": "true"
        },
        {
          "fieldName": "age",
          "condition": "ge",
          "value": "21"
        }
      ]
    }
  ]
}