basic

Basic cel2sql Example

This example demonstrates the basic usage of cel2sql to convert CEL (Common Expression Language) expressions to PostgreSQL SQL conditions.

What This Example Shows

• Schema Definition: How to define a PostgreSQL table schema using pg.Schema
• CEL Environment Setup: Creating a CEL environment with PostgreSQL type provider
• Expression Compilation: Compiling CEL expressions with type checking
• SQL Conversion: Converting compiled CEL expressions to PostgreSQL SQL

Running the Example

go run main.go

Expected Output

CEL Expression: employee.name == "John Doe" && employee.age >= 25 && employee.active
PostgreSQL SQL: employee.name = 'John Doe' AND employee.age >= 25 AND employee.active

Code Breakdown

1. Schema Definition

employeeSchema := pg.Schema{
    {Name: "name", Type: "text", Repeated: false},
    {Name: "age", Type: "integer", Repeated: false},
    {Name: "department", Type: "text", Repeated: false},
    {Name: "hired_at", Type: "timestamp with time zone", Repeated: false},
    {Name: "active", Type: "boolean", Repeated: false},
}

2. CEL Environment Setup

env, err := cel.NewEnv(
    cel.CustomTypeProvider(pg.NewTypeProvider(map[string]pg.Schema{
        "Employee": employeeSchema,
    })),
    cel.Variable("employee", cel.ObjectType("Employee")),
)

3. Expression Compilation and Conversion

ast, issues := env.Compile(`employee.name == "John Doe" && employee.age >= 25 && employee.active`)
sqlCondition, err := cel2sql.Convert(ast)

Supported PostgreSQL Types

• text - String values
• integer - Integer numbers
• boolean - Boolean values
• timestamp with time zone - Timestamps
• Arrays (with Repeated: true)
• And many more...

Next Steps

• Try modifying the CEL expression to test different operators
• Add more fields to the schema
• Experiment with array fields by setting Repeated: true
• Check out the LoadTableSchema example for dynamic schema loading