v1.8.4

The command line tool (and the library) can now filter by property.

The query language is loosely modeled after the jq query language. Here is an overview.

Example:

"properties": {
  "foo": {"bar": 1},
  "some": ["a", "b"],
  "value": 1,
  "string": "Some name"
}

Values are retrieved by putting a . in front of the property name. The property name must be quoted if it is a number or contains any non-alphabetic characters. Elements in arrays can be accesses either by simply using the array index after the dot, or by wrapping it in brackets.

.foo       // true, property "foo" exists
.foo.bar   // true, property "foo" is a dictionary containing "bar"
."foo"."bar" // true, same as above but quoted
.foo.x     // false, "foo" doesn't contain "x"
."foo.bar" // false, property "foo.bar" doesn't exist
.foo.[0]   // false, "foo" is not an array
.some.[0]  // true, "some" is an array and has an element at index "0"
.some.0    // true, same as above but without brackets
.some."0"  // false, "0" is a string key but "some" is not a dictionary

Comparisons can be expressed like this:

.value == "bar" // false
.value == 1  // true
.value != 1  // false
.value > 1   // false
.value >= 1  // true
.value < 1   // false
.value <= 1  // true
.string =~ /[Ss]ome/ // true
.string =~ /some/    // false
.string =~ /some/i   // true, case insensitive
.string =~ "^Some"   // true

Conditions (evaluated left to right):

.foo.bar == 1 and .value == 1 // true
.foo == 1 or .bar == 2        // false
.foo == 1 or .value == 1      // true
.foo not          // true if foo does not exist
.foo and .bar not // true if foo and bar don't exist together
.foo or .bar not  // true if neither foo nor bar exist
.foo.bar not      // true if "bar" in dictionary "foo" doesn't exist

Examples:

// Can use single quotes for strings
mvt query -p 14_8716_8015.vector.mvt ".area > 20000 and .class == 'hospital'"

// ... or double quotes, but they must be escaped
mvt query -p 14_8716_8015.vector.mvt ".area > 20000 and .class == \"hospital\""

// No need to quote the query if it doesn't conflict with your shell
// Print all features that have an "area" property
mvt query -p 14_8716_8015.vector.mvt .area
// Features which don't have "area" and "name" properties
mvt query -p 14_8716_8015.vector.mvt .area and .name not

// Case insensitive regular expression
vt query -p 14_8716_8015.vector.mvt ".name =~ /hopital/i"

// Case sensitive regular expression
mvt query -p 14_8716_8015.vector.mvt ".name =~ /Recherches?/"
// Can also use quotes instead of slashes
mvt query -p 14_8716_8015.vector.mvt ".name =~ 'Recherches?'"