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A FeatureDao provides typed read and write access to a single feature table inside a GeoPackage. Obtain one from an open GeoPackage — do not construct it directly. 
const featureDao = geoPackage.getFeatureDao('countries');
FeatureDao extends UserDao, so all generic query helpers from UserDao are also available on a FeatureDao.

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Creating a FeatureDao

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getFeatureDao()

Call this on an open GeoPackage to get a FeatureDao for the named table. 
geoPackage.getFeatureDao(tableName: string): FeatureDao

const featureDao = geoPackage.getFeatureDao('my_features');

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Querying rows

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queryForAll()

Returns a FeatureResultSet containing every row in the table. Iterate the result set and close it when done. 
queryForAll(): FeatureResultSet

const results = featureDao.queryForAll();
try {
  while (results.moveToNext()) {
    const row = results.getRow();
    console.log(row.getId(), row.getGeometry());
  }
} finally {
  results.close();
}
Always close the returned FeatureResultSet — failing to do so leaks the underlying SQLite cursor.

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queryForId()

Returns a FeatureResultSet filtered to the single row with the given primary key. 
queryForId(id: number): FeatureResultSet
​
id
number
required
Primary key value of the row to retrieve.
const resultSet = featureDao.queryForId(42);
if (resultSet.moveToNext()) {
  const row = resultSet.getRow();
}
resultSet.close();

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queryForIdRow()

Convenience wrapper around queryForId() that returns the first matching FeatureRow directly, or null if not found. 
queryForIdRow(id: number): FeatureRow
​
id
number
required
Primary key value of the row to retrieve.

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queryForFieldValues()

Returns a FeatureResultSet for all rows where each field in fieldValues matches. 
queryForFieldValues(fieldValues: FieldValues): FeatureResultSet
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fieldValues
FieldValues
required
A FieldValues map of column name to expected value.
import { FieldValues } from '@ngageoint/geopackage';

const fields = new FieldValues();
fields.addFieldValue('status', 'active');
const results = featureDao.queryForFieldValues(fields);

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query()

Returns a FeatureResultSet using an optional raw SQL WHERE clause and bind arguments. 
query(where?: string, whereArgs?: any[]): FeatureResultSet
​
where
string
SQL WHERE clause, without the WHERE keyword. Omit to return all rows.
​
whereArgs
any[]
Bind arguments that replace ? placeholders in where.
const results = featureDao.query('population > ?', [1_000_000]);

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Counting rows

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count()

Returns the total number of rows, optionally filtered by a WHERE clause. 
count(where?: string, whereArgs?: any[]): number

const total = featureDao.count();
const active = featureDao.count('status = ?', ['active']);

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getCount()

An alternative count helper that accepts the same optional WHERE clause parameters. 
getCount(where?: string, whereArgs?: any[]): number

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Writing rows

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newRow()

Creates and returns a blank FeatureRow backed by this table’s schema. Populate the row then pass it to create(). 
newRow(): FeatureRow

const row = featureDao.newRow();

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create()

Inserts a new row into the table and returns the new row’s id. 
create(row: FeatureRow): number
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row
FeatureRow
required
A FeatureRow obtained from newRow() with geometry and attribute values set.
​
return
number
The primary key id of the newly inserted row.
import { GeoPackageGeometryData } from '@ngageoint/geopackage';
import { Point } from '@ngageoint/simple-features-js';

const row = featureDao.newRow();
const geometryData = GeoPackageGeometryData.create(4326, new Point(false, false, -77.03, 38.89));
row.setGeometry(geometryData);
row.setValue('name', 'Washington, D.C.');
const newId = featureDao.create(row);

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update()

Updates an existing row in the table. Matches by the row’s primary key. 
update(row: FeatureRow): number
​
row
FeatureRow
required
The modified FeatureRow to persist. The row’s getId() must match an existing record.
​
return
number
Number of rows updated (should be 1 on success).

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deleteRow()

Deletes the row represented by the given FeatureRow. 
deleteRow(row: FeatureRow): number
​
row
FeatureRow
required
The row to delete. Uses the row’s getId() to locate the record.

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deleteById()

Deletes the row with the specified primary key. 
deleteById(id: number): number
​
id
number
required
Primary key of the row to delete.
​
return
number
Number of rows deleted (should be 0 or 1).

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Table metadata

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getTable()

Returns the underlying FeatureTable schema object describing the table’s columns. 
getTable(): FeatureTable

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getGeometryColumnName()

Returns the name of the geometry column in this feature table. 
getGeometryColumnName(): string

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getGeometryType()

Returns the GeometryType enum value declared for this table’s geometry column. 
getGeometryType(): GeometryType

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FeatureRow

A FeatureRow represents a single row from a feature table. Each row holds geometry data and zero or more attribute columns.

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getGeometry()

Returns the GeoPackageGeometryData wrapper containing the encoded geometry, or null if the geometry column is empty. 
getGeometry(): GeoPackageGeometryData

const geometryData = row.getGeometry();
const geometry = geometryData?.getGeometry(); // simple-features-js Geometry

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setGeometry()

Sets the geometry column value for this row. 
setGeometry(geometryData: GeoPackageGeometryData): void
​
geometryData
GeoPackageGeometryData
required
A GeoPackageGeometryData wrapping the geometry to store.

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getGeometryValue()

Convenience method — returns the decoded Geometry object directly from the geometry column, or null. 
getGeometryValue(): Geometry

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getValue()

Returns the value of the named column for this row. 
getValue(columnName: string): any
​
columnName
string
required
Name of the column to read.
const name = row.getValue('city_name') as string;

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setValue()

Sets the value of the named column for this row. 
setValue(columnName: string, value: any): void
​
columnName
string
required
Name of the column to write.
​
value
any
required
Value to assign. Must be compatible with the column’s declared data type.

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getId()

Returns the primary key value of this row. 
getId(): number
​
return
number
The integer primary key for this row.

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Full example

import {
  GeoPackageManager,
  GeoPackageGeometryData,
} from '@ngageoint/geopackage';
import { Point } from '@ngageoint/simple-features-js';

const geoPackage = await GeoPackageManager.open('./data.gpkg');
const featureDao = geoPackage.getFeatureDao('cities');

// Read all features
const results = featureDao.queryForAll();
try {
  while (results.moveToNext()) {
    const row = results.getRow();
    console.log(row.getId(), row.getValue('name'), row.getGeometryValue());
  }
} finally {
  results.close();
}

// Write a new feature
const newRow = featureDao.newRow();
newRow.setGeometry(
  GeoPackageGeometryData.create(4326, new Point(false, false, -0.1278, 51.5074))
);
newRow.setValue('name', 'London');
const id = featureDao.create(newRow);
console.log('Created row with id', id);

geoPackage.close();

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