EctoQueryParser

A query language parser for Ecto that converts human-readable filter strings into Ecto WHERE clauses. Designed for building user-facing search and filtering interfaces where filter expressions come from untrusted input.

Key Features

Rich query language - equality, comparison, LIKE/ILIKE, substring search, array containment, and logical operators with grouping
Built-in functions - string (UPPER, LOWER, TRIM, LENGTH, etc.), math (ABS, FLOOR, CEIL), and date/time (NOW, DATE_TRUNC, interval arithmetic)
Automatic joins - dotted identifiers like author.company.name resolve to LEFT JOINs via schema associations, with deduplication
JSONB support - dotted paths on :map fields generate json_extract_path queries with correct type casting
Field restrictions - control which fields users can filter on, with type annotations for JSON paths
Schemaless queries - define associations inline for dynamic table access without Ecto schemas
Integration tested - all generated SQL verified against a real PostgreSQL database

Example

# Parse a filter string into an Ecto query
{:ok, query} = EctoQueryParser.apply(
  Post,
  ~s{author.name == "alice" AND status == "published"}
)
Repo.all(query)

# With field restrictions and JSONB type casting
{:ok, query} = EctoQueryParser.apply(Post, filter,
  allowed_fields: [
    name: :string,
    metadata: :map,
    "metadata.view_count": :integer
  ]
)