Function compileSQL

packages/electric-db-collection/src/sql-compiler.ts:27–77

(
  options: LoadSubsetOptions,
  compileOptions?: CompileSQLOptions,
)

}

export function compileSQL<T>(
  options: LoadSubsetOptions,
  compileOptions?: CompileSQLOptions,
): SubsetParams {
  const { where, orderBy, limit } = options
  const encodeColumnName = compileOptions?.encodeColumnName

  const params: Array<T> = []
  const compiledSQL: CompiledSqlRecord = { params }

  if (where) {
    // TODO: this only works when the where expression's PropRefs directly reference a column of the collection
    //       doesn't work if it goes through aliases because then we need to know the entire query to be able to follow the reference until the base collection (cf. followRef function)
    compiledSQL.where = compileBasicExpression(where, params, encodeColumnName)
  }

  if (orderBy) {
    compiledSQL.orderBy = compileOrderBy(orderBy, params, encodeColumnName)
  }

  if (limit) {
    compiledSQL.limit = limit
  }

  // WORKAROUND for Electric bug: Empty subset requests don't load data
  // Add dummy "true = true" predicate when there's no where clause
  // This is always true so doesn't filter data, just tricks Electric into loading
  if (!where) {
    compiledSQL.where = `true = true`
  }

  // Serialize the values in the params array into PG formatted strings
  // and transform the array into a Record<string, string>
  const paramsRecord = params.reduce(
    (acc, param, index) => {
      const serialized = serialize(param)
      // Empty strings are valid query values (e.g., WHERE column = '')
      // Only omit null/undefined values from params
      if (param != null) {
        acc[`${index + 1}`] = serialized
      }
      return acc
    },
    {} as Record<string, string>,
  )

  return {
    ...compiledSQL,
    params: paramsRecord,
  }
}

/**
 * Quote PostgreSQL identifiers to handle mixed case column names correctly.