WhereClause

Property Overview

Property Details

fieldNames String[]

An array of the field names used in the where clause. It can be used to get the appropriate fields when querying layers.

Example:

// parse layer's definition expression into where clause object
sql.parseWhereClause(layer.definitionExpression, layer.fieldsIndex)
.then(function(clause){
  layer.queryFeatures({
    where: "1=1",
    // where clause object returns layer fields
    // use these fields to query features from the layer
    outFields: clause.fieldsNames
  }).then(function(results) {
   // process query results
  });
});

isStandardized Booleanreadonly

Returns true if the parsed where clause meets the requirements of standardized sql.

Method Overview

Method Details

calculateValue(feature){Object}

Executes the where clause against a feature to generate a value. It is used when the WhereClause is being used as a simple expression. For example, you can use the expression to gather values for statistics.

Parameter:

feature Object The feature to check against the where clause.

Returns:

Type	Description
Object	Returns a value after check feature against the provided where clause. Returns null if the provided value is unknown.

Example:

// calculate the grand total sales price of all features
featureLayer.queryFeatures().then(function(results){
  let total;
  const expression = "totalSales * totalPrice";
  sql.parseWhereClause(expression, layer.fieldsIndex)
  .then(function(whereClause){
    // check if the where clause meets requirements of standardized sql
    if (whereClause.isStandardized){
      features.forEach(function(feature){
        total += whereClause.calculateValue(feature)
      });
      console.log(total); // prints the total sales price of all features
    }
  });
});

testFeature(feature){Boolean}

Tests the attributes of a feature against the whereClause, and returns true if the test passes, false otherwise.

Parameter:

feature Object The feature to test against the whereClause.

Returns:

Type	Description
Boolean	Returns true if the test passes, false otherwise.

Example:

sql.parseWhereClause("POPULATION > 100000", layer.fieldsIndex)
.then(function(clause){
  let testResult = clause.testFeature(new Graphic({
    attributes: {
      POPULATION: 300000
   }
 });
 console.log(testResult); // prints true
});