Checks if the field is not null.

@param string $fieldName The field name.

@return boolean TRUE if the field is not null, FALSE otherwise.
483511
public function isNullable($fieldName)
    {
        $mapping = $this->getFieldMapping($fieldName);
        if ($mapping !== false) {
            return isset($mapping['nullable']) && $mapping['nullable'] == true;
        }
        return false;
    }
1230165
public Boolean getBoolean(String fieldName) {
		return hasValue(fieldName) ? Boolean.valueOf(String.valueOf(resultMap.get(fieldName))) : null;
	}
641551
public function fieldExists($fieldName, $tableName)
    {
        $tableFields = $this->getFields($tableName);
        $tableName = strtoupper($tableName);
        if (is_array($tableFields)) {
            $fieldName = strtoupper($fieldName);
            $tableFields = array_map('strtoupper', $tableFields);
            if (in_array("{$tableName}.{$fieldName}", $tableFields)) {
                return true;
            }
        }

        return false;
    }
1159365
function &fieldNamed($fieldName)
    {
        $return = NULL;
        if (isset($this->_fields[$fieldName])) {
            $return =& $this->_fields[$fieldName];
        }

        return $return;
    }
1119564
final public static function isNullable($fieldName) {
		
		$db = Database::getInstance();
		$column = $db->describeColumn(static::TABLE_NAME, $fieldName);
		
		if (is_null($column)) {
			return NULL;
		}
		
		return ('YES'==$column->Null ? TRUE : FALSE);
		
	}
8846
public function isCollectionValuedEmbed(string $fieldName) : bool
    {
        return isset($this->fieldMappings[$fieldName]['association']) &&
            $this->fieldMappings[$fieldName]['association'] === self::EMBED_MANY;
    }
537811
public function prepareFieldName(string $fieldName) : string
    {
        $fieldNames = $this->prepareQueryElement($fieldName, null, null, false);

        return $fieldNames[0][0];
    }
1071504
public function fieldHasError($fieldName)
    {
        foreach ($this->errors as $error) {
            if ($error->getParam() == $fieldName) {
                return true;
            }
        }

        if (!$this->isSubmitted()) {
            return false;
        }

        if (isset($this->validator) && $this->validator->fieldHasError($fieldName)) {
            return true;
        }
    }
281159
public function & GetField ($fieldName = '') {
		$result = NULL;
		if (isset($this->fields[$fieldName]))
			$result = & $this->fields[$fieldName];
		return $result;
	}
88801
protected function _isHashPath($fieldName = null) {
		if (empty($fieldName)) {
			return false;
		}

		$pos = mb_stripos($fieldName, '.{n}.');
		if ($pos !== false) {
			return true;
		}

		return false;
	}
1326370
public function getFieldNum($fieldName)
    {
        foreach( $this->_fields as $field ) {
            if( $field->name == $fieldName ) {
                return $field->number;
            }
        }

        return -1;
    }
786290
public function isSingleValuedAssociation($fieldName) : bool
    {
        return isset($this->associationMappings[$fieldName]['type']) &&
            $this->associationMappings[$fieldName]['type'] === 'one';
    }
775787
protected function checkFieldsForAction($fields, $funcName)
    {
        foreach ($fields as $field) {
            /** @skipUpgrade */
            if (ClassInfo::hasMethod($field, 'FieldList')) {
                if ($field = $this->checkFieldsForAction($field->FieldList(), $funcName)) {
                    return $field;
                }
            } elseif ($field->hasMethod($funcName) && $field->checkAccessAction($funcName)) {
                return $field;
            }
        }
        return null;
    }
653637
public function hasField($tableName, $fieldName)
    {
        if (!$this->hasTable($tableName)) {
            return false;
        }
        $fields = $this->fieldList($tableName);
        return array_key_exists($fieldName, $fields);
    }
1177653
public function exclude($fieldName = null)
    {
        if ( ! isset($this->query['select'])) {
            $this->query['select'] = array();
        }

        $fieldNames = is_array($fieldName) ? $fieldName : func_get_args();

        foreach ($fieldNames as $fieldName) {
            $this->query['select'][$fieldName] = 0;
        }

        return $this;
    }
1273824
public function isSingleValuedReference(string $fieldName) : bool
    {
        return isset($this->fieldMappings[$fieldName]['association']) &&
            $this->fieldMappings[$fieldName]['association'] === self::REFERENCE_ONE;
    }
1352177
public function getTypeOfField($fieldName)
    {
        if (!isset($this->fieldMappings[$fieldName])) {
            throw MappingException::mappingNotFound($this->name, $fieldName);
        }

        return isset($this->fieldMappings[$fieldName]) ?
                $this->fieldMappings[$fieldName]['type'] : null;
    }